[Federal Register Volume 87, Number 199 (Monday, October 17, 2022)]
[Proposed Rules]
[Pages 62753-62781]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2022-22223]
=======================================================================
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 87, 1031, and 1068
[EPA-HQ-OAR-2022-0389; FRL-5934-01-OAR]
RIN 2060-AT10
Proposed Finding That Lead Emissions From Aircraft Engines That
Operate on Leaded Fuel Cause or Contribute to Air Pollution That May
Reasonably Be Anticipated To Endanger Public Health and Welfare
AGENCY: Environmental Protection Agency (EPA).
ACTION: Proposed action.
-----------------------------------------------------------------------
SUMMARY: In this action, the Administrator is proposing to find that
lead air pollution may reasonably be anticipated to endanger the public
health and welfare within the meaning of section 231(a) of the Clean
Air Act. The Administrator is also proposing to find that engine
emissions of lead from certain aircraft cause or contribute to the lead
air pollution that may reasonably be anticipated to endanger public
health and welfare under section 231(a) of the Clean Air Act.
DATES:
Comments: Written comments must be received on or before January
17, 2023.
Public Hearing: The EPA plans to hold a virtual public hearing on
November 1, 2022. See SUPPLEMENTARY INFORMATION for information on
registering for a public hearing.
ADDRESSES: You may submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2022-0389, by any of the following methods:
Federal eRulemaking Portal: https://www.regulations.gov
(our preferred method). Follow the online instructions for submitting
comments.
Email: [email protected]. Include Docket ID No. EPA-
HQ-OAR-
[[Page 62754]]
2022-0389 in the subject line of the message.
Mail: U.S. Environmental Protection Agency, EPA Docket
Center, OAR, Docket EPA-HQ-OAR-2022-0389. Mail Code 28221T, 1200
Pennsylvania Avenue NW, Washington, DC 20460.
Hand Delivery or Courier (by scheduled appointment only):
EPA Docket Center, WJC West Building, Room 3334, 1301 Constitution
Avenue NW, Washington, DC 20004. The Docket Center's hours of
operations are 8:30 a.m.-4:30 p.m., Monday-Friday (except federal
holidays).
Instructions: All submissions received must include the Docket ID
No. for this action. Comments received may be posted without change to
https://www.regulations.gov/, including any personal information
provided. For detailed instructions on sending comments and additional
information on the process for this action, see the ``Public
Participation'' heading of the SUPPLEMENTARY INFORMATION section of
this document.
Public Hearing. EPA plans to hold a virtual public hearing for this
action. Please refer to Participation in Virtual Public Hearing in the
SUPPLEMENTARY INFORMATION section of this document for additional
information.
FOR FURTHER INFORMATION CONTACT: Marion Hoyer, Office of
Transportation and Air Quality, Assessment and Standards Division
(ASD), Environmental Protection Agency; Telephone number: (734) 214-
4513; Email address: [email protected].
SUPPLEMENTARY INFORMATION:
A. Public Participation
Written Comments: Submit your comments, identified by Docket ID No.
EPA-HQ-OAR-2022-0389, at https://www.regulations.gov (our preferred
method), or the other methods identified in the ADDRESSES section of
this document. Once submitted, comments cannot be edited or withdrawn
from the docket. The EPA may publish any comment received to its public
docket. Do not submit electronically any information you consider to be
Confidential Business Information (CBI), Proprietary Business
Information (PBI), or other information whose disclosure is restricted
by statute. Multimedia submissions (audio, video, etc.) must be
accompanied by a written comment. The written comment is considered the
official comment and should include discussion of all points you wish
to make. The EPA will generally not consider comments or comment
contents located outside of the primary submission (including such
content located on the web, cloud, or other file sharing system). For
additional submission methods, the full EPA public comment policy,
information about CBI, PBI, or multimedia submissions, and general
guidance on making effective comments, please visit https://www.epa.gov/dockets/commenting-epa-dockets.
Documents to which the EPA refers in this proposed action are
available online at https://www.regulations.gov/ in the docket for this
action (Docket EPA-HQ-OAR-2022-0389). To access reference documents in-
person and for additional assistance, please refer to the following
instructions.
The EPA plans to hold a virtual hearing on November 1, 2022. This
hearing will be held using Zoom. In order to attend the virtual public
hearing, all attendees (including those who will not be presenting
verbal testimony) must register in advance. Upon publication of this
document in the Federal Register, the EPA will begin registering
speakers for the hearing. To register to speak at the virtual hearing,
please use the instructions at https://www.epa.gov/regulations-emissions-vehicles-and-engines/regulations-lead-emissions-aircraft. If
you have questions regarding registration, consult the person listed in
the preceding FOR FURTHER INFORMATION CONTACT section of this document.
The last day to register to speak at the hearing will be October 31,
2022. Prior to the hearing, the EPA will post a general agenda that
will list registered speakers in approximate order at: https://www.epa.gov/regulations-emissions-vehicles-and-engines/regulations-lead-emissions-aircraft. The EPA will make every effort to follow the
schedule as closely as possible on the day of the hearing; however,
please plan for the hearings to run either ahead of schedule or behind
schedule.
The EPA anticipates that each commenter will have 5 minutes to
provide oral testimony. The EPA recommends submitting the text of your
oral testimony as written comments to the docket for this action. The
EPA may ask clarifying questions during the oral presentations but will
not respond to the presentations at that time. Written statements and
supporting information submitted during the comment period will be
considered with the same weight as oral testimony and supporting
information presented at the public hearing.
If you require the services of a translator or special
accommodations such as audio description, please identify these needs
when you register for the hearing no later than October 24, 2022. The
EPA may not be able to arrange accommodations without advanced notice.
B. General Information
Does this action apply to me?
Regulated Entities: In this action, the EPA is proposing to make
endangerment and cause or contribute findings for the lead air
pollution and engine emissions of lead from certain aircraft. The
classes of aircraft engines and of aircraft relevant to this proposed
action are referred to as ``covered aircraft engines'' and as ``covered
aircraft,'' respectively throughout this document. Covered aircraft
engines in this context means any aircraft engine that is capable of
using leaded aviation gasoline. Covered aircraft in this context means
all aircraft and ultralight vehicles \1\ equipped with covered engines.
Covered aircraft would, for example, include smaller piston-engine
aircraft such as the Cessna 172 (single-engine aircraft) and the
Beechcraft Baron G58 (twin-engine aircraft), as well as the largest
piston-engine aircraft--the Curtiss C-46 and the Douglas DC-6. Other
examples of covered aircraft would include rotorcraft,\2\ such as the
Robinson R44 helicopter, light-sport aircraft, and ultralight vehicles
equipped with piston engines. Because the majority of covered aircraft
are piston-engine powered, this document focuses on those aircraft (in
some contexts the EPA refers to these same engines as reciprocating
engines). All such references and examples used in this document are
covered aircraft as defined in this paragraph.
---------------------------------------------------------------------------
\1\ The FAA regulates ultralight vehicles under 14 CFR part 103.
\2\ Rotorcraft encompass helicopters, gyroplanes, and any other
heavier-than-air aircraft that depend principally for support in
flight on the lift generated by one or more rotors.
---------------------------------------------------------------------------
The proposed findings in this action, if finalized, would not
themselves apply new requirements to entities other than the EPA and
the Federal Aviation Administration (FAA). Specifically, if the EPA
issues final findings that lead emissions from covered aircraft engines
cause or contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare, then the EPA would,
under section 231 of the Clean Air Act, promulgate aircraft engine
emission standards for that air pollutant. In contrast to the findings,
those standards would apply to and have an effect on other entities
outside the federal government. Entities potentially interested in this
proposed action include those that manufacture
[[Page 62755]]
and sell covered aircraft engines and covered aircraft in the United
States and those who own or operate covered aircraft. Categories that
may be regulated in a future regulatory action include, but are not
limited to, those listed here:
----------------------------------------------------------------------------------------------------------------
Examples of potentially affected
Category NAICS \a\ code SIC \b\ code entities
----------------------------------------------------------------------------------------------------------------
Industry................................ 3364412 3724 Manufacturers of new aircraft
engines.
Industry................................ 336411 3721 Manufacturers of new aircraft.
Industry................................ 481219 4522 Aircraft charter services (i.e.,
general purpose aircraft used
for a variety of specialty air
and flying services). Aviation
clubs providing a variety of
air transportation activities
to the general public.
Industry................................ 611512 8249 and 8299 Flight Training.
----------------------------------------------------------------------------------------------------------------
\a\ North American Industry Classification System (NAICS).
\b\ Standard Industrial Classification (SIC) code.
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding potentially regulated entities likely to be
interested in this proposed action. This table lists examples of the
types of entities that the EPA is now aware of that could potentially
have an interest in this proposed action. If the EPA issues final
affirmative findings under section 231(a) of the Clean Air Act
regarding lead, the EPA would then undertake a future notice and
comment rulemaking to issue emission standards, and the FAA would be
required to prescribe regulations to ensure compliance with these
emissions standards pursuant to section 232 of the Clean Air Act. Such
findings also would trigger the FAA's statutory mandate pursuant to 49
U.S.C. 44714 to prescribe standards for the composition or chemical or
physical properties of an aircraft fuel or fuel additive to control or
eliminate aircraft emissions which EPA has decided endanger public
health or welfare under section 231(a) of the Clean Air Act. Other
types of entities not listed in the table could also be interested and
potentially affected by subsequent actions at some future time. If you
have any questions regarding the scope of this proposed action, consult
the person listed in the preceding FOR FURTHER INFORMATION CONTACT
section of this document.
C. Children's Health
Executive Order 13045 \3\ requires agencies to identify and assess
health and safety risks that may disproportionately affect children and
ensure that activities address disproportionate risks to children.
Children may be more vulnerable to environmental exposures and/or the
associated health effects, and therefore more at risk than adults.
These risks to children may arise because infants and children
generally eat more food, drink more water and breathe more air relative
to their size than adults do, and consequently may be exposed to
relatively higher amounts of contaminants. In addition, normal
childhood activity, such as putting hands in mouths or playing on the
ground, can result in exposures to contaminants that adults do not
typically have. Furthermore, environmental contaminants may pose health
risks specific to children because children's bodies are still
developing. For example, during periods of rapid growth such as fetal
development, infancy and puberty, their developing systems and organs
may be more easily harmed.\4\
---------------------------------------------------------------------------
\3\ E.O. 13045. Protection of Children From Environmental Health
Risks and Safety Risks. 62 FR 19885 (April 23, 1997).
\4\ EPA (2006) A Framework for Assessing Health Risks of
Environmental Exposures to Children. EPA, Washington, DC, EPA/600/R-
05/093F, 2006.
---------------------------------------------------------------------------
Protecting children's health from environmental risks is
fundamental to the EPA's mission. Since the inception of Executive
Order 13045, the understanding of children's environmental health has
broadened to include conception, infancy, early childhood and through
adolescence until 21 years of age.\5\ Because behavioral and
physiological characteristics can affect children's environmental
health risks, childhood and children's health is viewed with an
understanding of the concept of ``lifestages,'' which recognize unique
growth and developmental periods through which all humans pass.\6\
---------------------------------------------------------------------------
\5\ EPA. Memorandum: Issuance of EPA's 2021 Policy on Children's
Health. October 5, 2021. Available at https://www.epa.gov/system/files/documents/2021-10/2021-policy-on-childrens-health.pdf.
\6\ EPA. ``Childhood Lifestages relating to Children's
Environmental Health.'' Oct. 25, 2021. Retrieved from https://www.epa.gov/children/childhood-lifestages-relating-childrens-environmental-health on Nov. 22, 2021.
---------------------------------------------------------------------------
This document includes discussion and analysis that is focused
particularly on children. For example, as described in Sections III.A
and V of this document, the scientific evidence has long been
established demonstrating that young children (due to rapid growth and
development of the brain) are vulnerable to a range of neurological
effects resulting from exposure to lead. Low levels of lead in young
children's blood have been linked to adverse effects on intellect,
concentration, and academic achievement, and as the EPA has previously
noted ``there is no evidence of a threshold below which there are no
harmful effects on cognition from [lead] exposure.'' \7\ Evidence
suggests that while some neurocognitive effects of lead in children may
be transient, some lead-related cognitive effects may be irreversible
and persist into adulthood, potentially contributing to lower
educational attainment and financial well-being.\8\ The 2013 Lead ISA
notes that in epidemiologic studies, postnatal (early childhood) blood
lead levels are consistently associated with cognitive function
decrements in children and adolescents.\9\ In Section II.A.5 of this
document, we describe the number of children living near and attending
school near airports and provide a proximity analysis of the potential
for greater representation of children in the near-airport environment
compared with neighboring areas.
---------------------------------------------------------------------------
\7\ EPA (2013) ISA for Lead. Executive Summary ``Effects of Pb
Exposure in Children.'' pp. lxxxvii-lxxxviii. EPA/600/R-10/075F,
2013. See also, National Toxicology Program (NTP) (2012) NTP
Monograph: Health Effects of Low-Level Lead. Available at https://ntp.niehs.nih.gov/go/36443.
\8\ EPA (2013) ISA for Lead. Executive Summary ``Effects of Pb
Exposure in Children.'' pp. lxxxvii-lxxxviii. EPA/600/R-10/075F,
2013.
\9\ EPA (2013) ISA for Lead. Section 1.9.4. ``Pb Exposure and
Neurodevelopmental Deficits in Children.'' p. I-75. EPA/600/R-10/
075F, 2013.
---------------------------------------------------------------------------
D. Environmental Justice
Executive Order 12898 establishes federal executive policy on
environmental justice. It directs federal agencies, to the greatest
extent practicable and permitted by law, to make achieving
environmental justice part of their mission by identifying and
addressing, as appropriate, disproportionately high and adverse human
health or environmental effects
[[Page 62756]]
of their programs, policies, and activities on people of color
populations and low-income populations in the United States.\10\ The
EPA defines environmental justice as the fair treatment and meaningful
involvement of all people regardless of race, color, national origin,
or income with respect to the development, implementation, and
enforcement of environmental laws, regulations, and policies.\11\
---------------------------------------------------------------------------
\10\ 59 FR 7629 (Feb. 16, 1994).
\11\ Fair treatment means that ``no group of people should bear
a disproportionate burden of environmental harms and risks,
including those resulting from the negative environmental
consequences of industrial, governmental and commercial operations
or programs and policies.'' Meaningful involvement occurs when ``1)
potentially affected populations have an appropriate opportunity to
participate in decisions about a proposed activity [e.g.,
rulemaking] that will affect their environment and/or health; 2) the
public's contribution can influence the regulatory Agency's
decision; 3) the concerns of all participants involved will be
considered in the decision-making process; and 4) [the EPA will]
seek out and facilitate the involvement of those potentially
affected.'' A potential EJ concern is defined as ``the actual or
potential lack of fair treatment or meaningful involvement of
minority populations, low-income populations, Tribes, and indigenous
peoples in the development, implementation and enforcement of
environmental laws, regulations and policies.'' See, EPA's
Environmental Justice During the Development of an Action. Available
at https://www.epa.gov/sites/default/files/2015-06/documents/considering-ej-in-rulemaking-guide-final.pdf. See also https://www.epa.gov/environmentaljustice.
---------------------------------------------------------------------------
Executive Order 14008 also calls on federal agencies to make
achieving environmental justice part of their missions ``by developing
programs, policies, and activities to address the disproportionately
high and adverse human health, environmental, climate-related and other
cumulative impacts on disadvantaged communities, as well as the
accompanying economic challenges of such impacts.'' \12\ It also
declares a policy ``to secure environmental justice and spur economic
opportunity for disadvantaged communities that have been historically
marginalized and overburdened by pollution and under-investment in
housing, transportation, water and wastewater infrastructure and health
care.'' Under Executive Order 13563, federal agencies may consider
equity, human dignity, fairness, and distributional considerations,
where appropriate and permitted by law.\13\
---------------------------------------------------------------------------
\12\ 86 FR 7619 (Feb. 1, 2021).
\13\ 76 FR 3821 (Jan. 18, 2011).
---------------------------------------------------------------------------
The United States has made substantial progress in reducing lead
exposure, but disparities remain along racial, ethnic, and
socioeconomic lines. For example, blood lead levels in children from
low-income households remain higher than those in children from higher
income households, and the most exposed Black children still have
higher blood lead levels than the most exposed non-Hispanic White
children.\14\ \15\ Depending on the levels and associated risk, such
blood lead levels may lead to lifelong health effects and barriers to
social and economic well-being.\16\
---------------------------------------------------------------------------
\14\ EPA (2013) ISA for Lead. Section 5.4. ``Summary.'' pp. 5-40
through 5-42. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\15\ EPA (2022) ``America's Children and the Environment.''
Summary of blood lead levels in children updated in 2022, available
at https://www.epa.gov/americaschildrenenvironment/biomonitoring-lead. Data source: Centers for Disease Control and Prevention,
National Report on Human Exposure to Environmental Chemicals. Blood
Lead (2011-2018). Updated March 2022. Available at https://www.cdc.gov/exposurereport/report/pdf/cgroup2_LBXBPB_2011-p.pdf.
\16\ EPA (2013) ISA for Lead. Section 1.9.1. ``Public Health
Significance.'' p. 1-68; Section 1.9.5. ``Reversibility and
Persistence of Neurotoxic Effects of Pb.'' p. 1-76. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
In this action, the EPA is undertaking an evaluation, under section
231(a)(2)(A) of the Clean Air Act, of whether emissions of lead from
engines in covered aircraft may cause or contribute to air pollution
that may reasonably be anticipated to endanger public health or
welfare. We are not proposing emission standards at this time, and
therefore, our consideration of environmental justice is focused on
describing populations living near airports in the United States.
Section II.A.5 of this document, and the Technical Support Document
\17\ for this action describe the scientific evidence and analyses
conducted by the EPA that provide information about the disparity in
residential location for some low-income populations, people of color
and some indigenous peoples in the United States, particularly Alaska
Natives, with regard to their proximity to some airports where covered
aircraft operate. The information presented in Section II.A.5 of this
document indicates that there is a greater prevalence of people of
color and of low-income populations within 500 meters or one kilometer
of some airports compared with people living more distant. If such
differences were to contribute to disproportionate and adverse impacts
on people of color and low-income populations, they could indicate a
potential environmental justice concern.
---------------------------------------------------------------------------
\17\ EPA (2022) Technical Support Document (TSD) for the EPA's
Proposed Finding that Lead Emissions from Aircraft Engines that
Operate on Leaded Fuel Cause or Contribute to Air Pollution that May
Reasonably Be Anticipated to Endanger Public Health and Welfare.
EPA, Washington, DC, EPA-420-R-22-025, 2022. Available in the docket
for this action.
---------------------------------------------------------------------------
Table of Contents
I. Executive Summary
II. Overview and Context for This Proposal
A. Background Information Helpful to Understanding This Proposal
1. Piston-Engine Aircraft and the Use of Leaded Aviation
Gasoline
2. Emissions of Lead From Piston-Engine Aircraft
3. Concentrations of Lead in Air Attributable to Emissions From
Piston-Engine Aircraft
4. Fate and Transport of Emissions of Lead From Piston-Engine
Aircraft
5. Consideration of Environmental Justice and Children in
Populations Residing Near Airports
B. Federal Actions To Reduce Lead Exposure
C. History of Lead Endangerment Petitions for Rulemaking and the
EPA Responses
III. Legal Framework for This Action
A. Statutory Text and Basis for This Proposal
B. Considerations for the Endangerment and Cause or Contribute
Analyses Under Section 231(a)(2)(A)
C. Regulatory Authority for Emission Standards
IV. The Proposed Endangerment Finding Under CAA Section 231
A. Scientific Basis of the Endangerment Finding
1. Lead Air Pollution
2. Health Effects and Lead Air Pollution
3. Welfare Effects and Lead Air Pollution
B. Proposed Endangerment Finding
V. The Proposed Cause or Contribute Finding Under CAA Section 231
A. Proposed Definition of the Air Pollutant
B. The Data Used To Evaluate the Proposed Cause or Contribute
Finding
C. Proposed Cause or Contribution Finding for Lead
VI. Statutory Authority and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Paperwork Reduction Act (PRA)
C. Regulatory Flexibility Act (RFA)
D. Unfunded Mandates Reform Act (UMRA)
E. Executive Order 13132: Federalism
F. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
G. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
I. National Technology Transfer and Advancement Act (NTTAA)
J. Executive Order 12898: Federal Actions To Address
Environmental Justice in Minority Populations and Low-Income
Populations
K. Determination Under Section 307(d)
VII. Statutory Provisions and Legal Authority
I. Executive Summary
Pursuant to section 231(a)(2)(A) of the Clean Air Act (CAA or Act),
the Administrator proposes to find that
[[Page 62757]]
emissions of lead from covered aircraft engines cause or contribute to
lead air pollution that may reasonably be anticipated to endanger
public health and welfare. Covered aircraft would, for example, include
smaller piston-engine aircraft such as the Cessna 172 (single-engine
aircraft) and the Beechcraft Baron G58 (twin-engine aircraft), as well
as the largest piston-engine aircraft--the Curtiss C-46 and the Douglas
DC-6. Other examples of covered aircraft would include rotorcraft, such
as the Robinson R44 helicopter, light-sport aircraft, and ultralight
vehicles equipped with piston engines.
For purposes of this action, the EPA is proposing to define the
``air pollution'' referred to in section 231(a)(2)(A) of the CAA as
lead, which we also refer to as the lead air pollution in this
document.\18\ In proposing to find that the lead air pollution may
reasonably be anticipated to endanger the public health and welfare,
the EPA relies on the extensive scientific evidence critically assessed
in the 2013 Integrated Science Assessment for Lead (2013 Lead ISA) and
the previous Air Quality Criteria Documents (AQCDs) for Lead, which the
EPA prepared to serve as the scientific foundation for periodic reviews
of the National Ambient Air Quality Standards (NAAQS) for lead.\19\
\20\ \21\ \22\
---------------------------------------------------------------------------
\18\ As noted in Section IV.A of this notice, the lead air
pollution that we are considering in this proposed finding can occur
as elemental lead or in lead-containing compounds.
\19\ EPA (2013) ISA for Lead. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
\20\ EPA (2006) AQC for Lead. EPA, Washington, DC, EPA/600/R-5/
144aF, 2006.
\21\ EPA (1986) AQC for Lead. EPA, Washington, DC, EPA-600/8-83/
028aF-dF, 1986.
\22\ EPA (1977) AQC for Lead. EPA, Washington, DC, EPA-600/8-77-
017 (NTIS PB280411), 1977.
---------------------------------------------------------------------------
Further, for purposes of this action, the EPA is proposing to
define the ``air pollutant'' referred to in CAA section 231(a)(2)(A) as
lead, which we also refer to as the lead air pollutant in this
document.\23\ Accordingly, the Administrator is proposing to find that
emissions of the lead air pollutant from covered aircraft engines cause
or contribute to the lead air pollution that may reasonably be
anticipated to endanger public health and welfare under CAA section
231(a)(2)(A).
---------------------------------------------------------------------------
\23\ As noted in Section V.A of this notice, the lead air
pollutant we are considering in this proposed finding can occur as
elemental lead or in lead-containing compounds.
---------------------------------------------------------------------------
In addition to the proposed findings and the science on which they
are based, this document includes an overview and background context
helpful to understanding the source sector in the context of this
proposal, a brief summary of some of the federal actions focused on
reducing lead exposures, and the legal framework for this action.
II. Overview and Context for This Proposal
We summarize here background information that provides additional
context for this proposed action. This includes information on the
population of aircraft that have piston engines, information on the use
of leaded aviation gasoline (avgas) in covered aircraft, physical and
chemical characteristics of lead emissions from engines used in covered
aircraft, concentrations of lead in air from these engine emissions,
and the fate and transport of lead emitted by engines used in such
aircraft. We also include here an analysis of populations residing near
and attending school near airports and an analysis of potential
environmental justice implications with regard to residential proximity
to runways where covered aircraft operate. This section ends with a
description of a broad range of federal actions to reduce lead exposure
from a variety of environmental media and a summary of citizen
petitions for rulemaking regarding lead emissions from covered aircraft
and the EPA responses.
A. Background Information Helpful to Understanding This Proposal
This proposal draws extensively from the EPA's scientific
assessments for lead, which are developed as part of the EPA's periodic
reviews of the air quality criteria \24\ for lead and the lead
NAAQS.\25\ These scientific assessments provide a comprehensive review,
synthesis, and evaluation of the most policy-relevant science that
builds upon the conclusions of previous assessments. In the information
that follows, we discuss and describe scientific evidence summarized in
the most recent assessment, the 2013 Lead ISA \26\ as well as
information summarized in previous assessments, including the 1977,
1986, and 2006 AQCDs.\27\ \28\ \29\
---------------------------------------------------------------------------
\24\ Under section 108(a)(2) of the CAA, air quality criteria
are intended to ``accurately reflect the latest scientific knowledge
useful in indicating the kind and extent of all identifiable effects
on public health or welfare which may be expected from the presence
of [a] pollutant in the ambient air . . . .'' Section 109 of the CAA
directs the Administrator to propose and promulgate ``primary'' and
``secondary'' NAAQS for pollutants for which air quality criteria
are issued. Under CAA section 109(d)(1), EPA must periodically
complete a thorough review of the air quality criteria and the NAAQS
and make such revisions as may be appropriate in accordance with
sections 108 and 109(b) of the CAA. A fuller description of these
legislative requirements can be found, for example, in the ISA (see
2013 Lead ISA, p. lxix).
\25\ Section 109(b)(1) defines a primary standard as one ``the
attainment and maintenance of which in the judgment of the
Administrator, based on such criteria and allowing an adequate
margin of safety, are requisite to protect the public health.'' A
secondary standard, as defined in section 109(b)(2), must ``specify
a level of air quality the attainment and maintenance of which, in
the judgment of the Administrator, based on such criteria, is
requisite to protect the public welfare from any known or
anticipated adverse effects associated with the presence of [the]
pollutant in the ambient air.''
\26\ EPA (2013) ISA for Lead. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
\27\ EPA (1977) AQC for Lead. EPA, Washington, DC, EPA-600/8-77-
017 (NTIS PB280411), 1977.
\28\ EPA (1986) AQC for Lead. EPA, Washington, DC, EPA-600/8-83/
028aF-dF (NTIS PB87142386), 1986.
\29\ EPA (2006) AQC for Lead. EPA, Washington, DC, EPA/600/R-5/
144aF, 2006.
---------------------------------------------------------------------------
As described in the 2013 Lead ISA, lead emitted to ambient air is
transported through the air and is distributed from air to other
environmental media through deposition.\30\ Lead emitted in the past
can remain available for environmental or human exposure for extended
time in some areas.\31\ Depending on the environment where it is
deposited, it may to various extents be resuspended into the ambient
air, integrated into the media on which it deposits, or transported in
surface water runoff to other areas or nearby waterbodies.\32\ Lead in
the environment today may have been airborne yesterday or emitted to
the air long ago.\33\ Over time, lead that was initially emitted to air
can become less available for environmental circulation by
sequestration in soil, sediment and other reservoirs.\34\
---------------------------------------------------------------------------
\30\ EPA (2013) ISA for Lead. Section 3.1.1. ``Pathways for Pb
Exposure.'' p. 3-1. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\31\ EPA (2013) ISA for Lead. Section 3.7.1. ``Exposure.'' p. 3-
144. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\32\ EPA (2013) ISA for Lead. Section 6.2. ``Fate and Transport
of Pb in Ecosystems.'' p. 6-62. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
\33\ EPA (2013) ISA for Lead. Section 2.3. ``Fate and Transport
of Pb.'' p. 2-24. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\34\ EPA (2013) ISA for Lead. Section 1.2.1. ``Sources, Fate and
Transport of Ambient Pb;'' p. 1-6. Section 2.3. ``Fate and Transport
of Pb.'' p. 2-24. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
The multimedia distribution of lead emitted into ambient air
creates multiple air-related pathways of human and ecosystem exposure.
These pathways may involve media other than air, including indoor and
outdoor dust, soil, surface water and sediments, vegetation and biota.
The human exposure pathways for lead emitted into air include
inhalation of ambient air or ingestion of food, water or other
materials, including dust and soil, that have been contaminated through
a pathway involving lead deposition from
[[Page 62758]]
ambient air.\35\ Ambient air inhalation pathways include both
inhalation of air outdoors and inhalation of ambient air that has
infiltrated into indoor environments.\36\ The air-related ingestion
pathways occur as a result of lead emissions to air being distributed
to other environmental media, where humans can be exposed to it via
contact with and ingestion of indoor and outdoor dusts, outdoor soil,
food and drinking water.
---------------------------------------------------------------------------
\35\ EPA (2013) ISA for Lead. Section 3.1.1. ``Pathways for Pb
Exposure.'' p. 3-1. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\36\ EPA (2013) ISA for Lead. Sections 1.3. ``Exposure to
Ambient Pb.'' p. 1-11. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
The scientific evidence documents exposure to many sources of lead
emitted to the air that have resulted in higher blood lead levels,
particularly for people living or working near sources, including
stationary sources, such as mines and smelters, and mobile sources,
such as cars and trucks when lead was a gasoline
additive.37 38 39 40 41 42 Similarly, with regard to
emissions from engines used in covered aircraft there have been studies
reporting positive associations of children's blood lead levels with
proximity to airports and activity by covered aircraft,43 44
thus indicating potential for children's exposure to lead from covered
aircraft engine emissions. A recent study evaluating cardiovascular
mortality rates in adults 65 and older living within a few kilometers
and downwind of runways, while not evaluating blood lead levels, found
higher mortality rates in adults living near single-runway airports in
years with more piston-engine air traffic, but not in adults living
near multi-runway airports, suggesting the potential for adverse adult
health effects near some airports.\45\
---------------------------------------------------------------------------
\37\ EPA (2013) ISA for Lead. Sections 3.4.1. ``Pb in Blood.''
p. 3-85; Section 5.4. ``Summary.'' p. 5-40. EPA, Washington, DC,
EPA/600/R-10/075F, 2013.
\38\ EPA (2006) AQC for Lead. Chapter 3. EPA, Washington, DC,
EPA/600/R-5/144aF, 2006.
\39\ EPA (1986) AQC for Lead. Section 1.11.3. EPA, Washington,
DC, EPA-600/8-83/028aF-dF (NTIS PB87142386), 1986.
\40\ EPA (1977) AQC for Lead. Section 12.3.1.1. ``Air
Exposures.'' p. 12-10. EPA, Washington, DC, EPA-600/8-77-017 (NTIS
PB280411), 1977.
\41\ EPA (1977) AQC for Lead. Section 12.3.1.2. ``Air
Exposures.'' p. 12-10. EPA, Washington, DC, EPA-600/8-77-017 (NTIS
PB280411), 1977.
\42\ EPA (1977) AQC for Lead. Section 12.3.1.1. ``Air
Exposures.'' p. 12-10. EPA, Washington, DC, EPA-600/8-77-017 (NTIS
PB280411), 1977.
\43\ Miranda et al., 2011. A Geospatial Analysis of the Effects
of Aviation Gasoline on Childhood Blood Lead Levels. Environmental
Health Perspectives. 119:1513-1516.
\44\ Zahran et al., 2017. The Effect of Leaded Aviation Gasoline
on Blood Lead in Children. Journal of the Association of
Environmental and Resource Economists. 4(2):575-610.
\45\ Klemick et al., 2022. Cardiovascular Mortality and Leaded
Aviation Fuel: Evidence from Piston-Engine Air Traffic in North
Carolina. International Journal of Environmental Research and Public
Health. 19(10):5941.
---------------------------------------------------------------------------
1. Piston-Engine Aircraft and the Use of Leaded Aviation Gasoline
Aircraft operating in the U.S. are largely powered by either
turbine engines or piston engines, although other propulsion systems
are in use and in development. Turbine-engine powered aircraft and a
small percentage of piston-engine aircraft (i.e., those with diesel
engines) operate on fuel that does not contain a lead additive. Covered
aircraft, which are predominantly piston-engine powered aircraft,
operate on leaded avgas. Examples of covered aircraft include smaller
piston-powered aircraft such as the Cessna 172 (single-engine aircraft)
and the Beechcraft Baron G58 (twin-engine aircraft), as well as the
largest piston-engine aircraft--the Curtiss C-46 and the Douglas DC-6.
Additionally, some rotorcraft, such as the Robinson R44 helicopter,
light-sport aircraft, and ultralight vehicles can have piston engines
that operate using leaded avgas.
Lead is added to avgas in the form of tetraethyl lead. Tetraethyl
lead helps boost fuel octane, prevents engine knock, and prevents valve
seat recession and subsequent loss of compression for engines without
hardened valves. There are three main types of leaded avgas: 100
Octane, which can contain up to 4.24 grams of lead per gallon (1.12
grams of lead per liter), 100 Octane Low Lead (100LL), which can
contain up to 2.12 grams of lead per gallon (0.56 grams of lead per
liter), and 100 Octane Very Low Lead (100VLL), which can contain up to
0.71 grams of lead per gallon (0.45 grams of lead per liter).\46\
Currently, 100LL is the most commonly available and most commonly used
type of avgas.\47\ Tetraethyl lead was first used in piston-engine
aircraft in 1927.\48\ Commercial and military aircraft in the U.S.
operated on 100 Octane leaded avgas into the 1950s, but in subsequent
years, the commercial and military aircraft fleet largely converted to
turbine-engine powered aircraft which do not use leaded
avgas.49 50 The use of avgas containing approximately 4
grams of lead per gallon continued in piston-engine aircraft until the
early 1970s when 100LL became the dominant leaded fuel in use.
---------------------------------------------------------------------------
\46\ ASTM International (May 1, 2021) Standard Specification for
Leaded Aviation Gasolines D910-21.
\47\ National Academies of Sciences, Engineering, and Medicine
(NAS). 2021. Options for Reducing Lead Emissions from Piston-Engine
Aircraft. Washington, DC: The National Academies Press. https://doi.org/10.17226/26050.
\48\ Ogston 1981. A Short History of Aviation Gasoline
Development, 1903-1980.Society of Automotive Engineers. p. 810848.
\49\ U.S. Department of Commerce Civil Aeronautics
Administration. Statistical Handbook of Aviation (Years 1930-1959).
https://babel.hathitrust.org/cgi/pt?id=mdp.39015027813032&view=1up&seq=899.
\50\ U.S. Department of Commerce Civil Aeronautics
Administration. Statistical Handbook of Aviation (Years 1960-1971).
https://babel.hathitrust.org/cgi/pt?id=mdp.39015004520279&view=1up&seq=9&skin=2021.
---------------------------------------------------------------------------
There are two sources of data from the federal government that
provide annual estimates of the volume of leaded avgas supplied and
consumed in the U.S.: the Department of Energy, Energy Information
Administration (DOE EIA) provides information on the volume of leaded
avgas supplied in the U.S.,\51\ and the FAA provides information on the
volume of leaded avgas consumed in the U.S.\52\ Over the ten-year
period from 2011 through 2020, DOE estimates of the annual volume of
leaded avgas supplied averaged 184 million gallons, with year-on-year
fluctuations in fuel supplied ranging from a 25 percent increase to a
29 percent decrease. Over the same period, from 2011 through 2020, the
FAA estimates of the annual volume of leaded avgas consumed averaged
196 million gallons, with year-on-year fluctuations in fuel consumed
ranging from an eight percent increase to a 14 percent decrease. The
FAA forecast for consumption of leaded avgas in the U.S. ranges from
185 million gallons in 2026 to 179 million gallons in 2041, a decrease
of three percent in that period.\53\ As described later in this
section, while the consumption of leaded avgas is expected to decrease
three percent from 2026 to 2041, FAA projects increased activity at
some airports and decreased activity at other airports out to 2045.
---------------------------------------------------------------------------
\51\ DOE. EIA. Petroleum and Other Liquids; Supply and
Disposition. Aviation Gasoline in Annual Thousand Barrels. Fuel
production volume data obtained from https://www.eia.gov/dnav/pet/pet_sum_snd_a_eppv_mbbl_a_cur-1.htm and https://www.eia.gov/dnav/pet/hist/LeafHandler.ashx?n=PET&s=C400000001&f=A on Dec., 30, 2021.
\52\ Department of Transportation (DOT). FAA. Aviation Policy
and Plans. FAA Aerospace Forecast Fiscal Years 2009-2025. p. 81.
Available at http://www.faa.gov/data_research/aviation/aerospace_forecasts/2009-2025/media/2009%20Forecast%20Doc.pdf. This
document provides historical data for 2000-2008 as well as forecast
data.
\53\ DOT. FAA. Aviation Policy and Plans. Table 23. p. 111. FAA
Aerospace Forecast Fiscal Years 2021-2041. Available at https://www.faa.gov/sites/faa.gov/files/data_research/aviation/aerospace_forecasts/FY2021-41_FAA_Aerospace_Forecast.pdf.
---------------------------------------------------------------------------
[[Page 62759]]
The FAA's National Airspace System Resource (NASR) \54\ provides a
complete list of operational airport facilities in the U.S. Among the
approximately 19,600 airports listed in the NASR, approximately 3,300
are included in the National Plan of Integrated Airport Systems (NPIAS)
and support the majority of piston-engine aircraft activity that occurs
annually in the U.S.\55\ While less aircraft activity occurs at the
remaining 15,336 airports, that activity is conducted predominantly by
piston-engine aircraft. Approximately 6,000 airports have been in
operation since the early 1970s when the leaded fuel being used
contained up to 4.24 grams of lead per gallon of avgas.\56\ The
activity by piston-engine aircraft spans a range of purposes, as
described further below. In Alaska this fleet of aircraft currently
play a critical role in the transportation infrastructure.
---------------------------------------------------------------------------
\54\ See FAA. NASR. Available at https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/eNASR_Browser/.
\55\ FAA (2020) National Plan of Integrated Airport Systems
(NPIAS) 2021-2025 Published by the Secretary of Transportation
Pursuant to Title 49 U.S. Code, Section 47103. Retrieved on Nov. 3,
2021 from: https://www.faa.gov/airports/planning_capacity/npias/current/media/NPIAS-2021-2025-Narrative.pdf.
\56\ See FAA's NASR. Available at https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/eNASR_Browser/.
---------------------------------------------------------------------------
As of 2019, there were 171,934 piston-engine aircraft in the
U.S.\57\ This total includes 128,926 single-engine aircraft, 12,470
twin-engine aircraft, and 3,089 rotorcraft.\58\ The average age of
single-engine aircraft in 2018 was 46.8 years and the average age of
twin-engine aircraft in 2018 was 44.7 years old.\59\ In 2019, 883 new
piston-engine aircraft were manufactured in the U.S. some of which are
exported.\60\ For the period from 2019 through 2041, the fleet of fixed
wing \61\ piston-engine aircraft is projected to decrease at an annual
average rate of 0.9 percent, and the hours flown by these aircraft is
projected to decrease 0.9 percent per year from 2019 to 2041.\62\ An
annual average growth rate in the production of piston-engine powered
rotorcraft of 0.9 percent is forecast, with a commensurate 1.9 percent
increase in hours flown in that period by piston-engine powered
rotorcraft.\63\ There were approximately 664,565 pilots certified to
fly general aviation aircraft in the U.S. in 2021.\64\ This included
197,665 student pilots and 466,900 non-student pilots. In addition,
there were more than 301,000 FAA Non-Pilot Certificated mechanics.\65\
---------------------------------------------------------------------------
\57\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 1: Historical General Aviation and Air Taxi Measures.
Table 1.1--General Aviation and Part 135 Number of Active Aircraft
By Aircraft Type 2008-2019. Retrieved on Dec., 27, 2021 at https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/. Separately, FAA maintains a database of FAA-registered
aircraft and as of January 6, 2022 there were 222,592 piston-engine
aircraft registered with FAA. See: https://registry.faa.gov/aircraftinquiry/.
\58\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 1: Historical General Aviation and Air Taxi Measures.
Table 1.1--General Aviation and Part 135 Number of Active Aircraft
By Aircraft Type 2008-2019. Retrieved on Dec., 27, 2021 at https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/.
\59\ General Aviation Manufacturers Association (GAMA) (2019)
General Aviation Statistical Databook and Industry Outlook, p.27.
Retrieved on October 7, 2021 from: https://gama.aero/wp-content/uploads/GAMA_2019Databook_Final-2020-03-20.pdf.
\60\ GAMA (2019) General Aviation Statistical Databook and
Industry Outlook, p.16. Retrieved on October 7, 2021 from: https://gama.aero/wp-content/uploads/GAMA_2019Databook_Final-2020-03-20.pdf.
\61\ There are both fixed-wing and rotary-wing aircraft; and
airplane is an engine-driven, fixed-wing aircraft and a rotorcraft
is an engine-driven rotary-wing aircraft.
\62\ See FAA Aerospace Forecast Fiscal Years 2021-2041. p. 28.
Available at https://www.faa.gov/sites/faa.gov/files/data_research/aviation/aerospace_forecasts/FY2021-41_FAA_Aerospace_Forecast.pdf.
\63\ FAA Aerospace Forecast Fiscal Years 2021-2041. Table 28. p.
116., and Table 29. p. 117. Available at https://www.faa.gov/sites/faa.gov/files/data_research/aviation/aerospace_forecasts/FY2021-41_FAA_Aerospace_Forecast.pdf.
\64\ FAA. U.S. Civil Airmen Statistics. 2021 Active Civil Airman
Statistics. Retrieved from https://www.faa.gov/data_research/aviation_data_statistics/civil_airmen_statistics on May 20, 2022.
\65\ FAA. U.S. Civil Airmen Statistics. 2021 Active Civil Airman
Statistics. Retrieved from https://www.faa.gov/data_research/aviation_data_statistics/civil_airmen_statistics on May 20, 2022.
---------------------------------------------------------------------------
Piston-engine aircraft are used to conduct flights that are
categorized as either general aviation or air taxi. General aviation
flights are defined as all aviation other than military and those
flights by scheduled commercial airlines. Air taxi flights are short
duration flights made by small commercial aircraft on demand. The hours
flown by aircraft in the general aviation fleet are comprised of
personal and recreational transportation (67 percent), business (12
percent), instructional flying (8 percent), medical transportation
(less than one percent), and the remainder includes hours spent in
other applications such as aerial observation and aerial
application.\66\ Aerial application for agricultural activity includes
crop and timber production, which involve fertilizer and pesticide
application and seeding cropland. In 2019, aerial application in
agriculture represented 883,600 hours flown by general aviation
aircraft, and approximately 17.5 percent of these total hours were
flown by piston-engine aircraft.\67\
---------------------------------------------------------------------------
\66\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 1: Historical General Aviation and Air Taxi Measures.
Table 1.4--General Aviation and Part 135 Total Hours Flown By Actual
Use 2008-2019 (Hours in Thousands). Retrieved on Dec., 27, 2021 at
https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/.
\67\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 3: Primary and Actual Use. Table 3.2--General Aviation
and Part 135 Total Hours Flown by Actual Use 2008-2019 (Hours in
Thousands). Retrieved on Mar., 22, 2022 at https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/.
---------------------------------------------------------------------------
Approximately 71 percent of the hours flown that are categorized as
general aviation activity are conducted by piston-engine aircraft, and
17 percent of the hours flown that are categorized as air taxi are
conducted by piston-engine aircraft.\68\ From the period 2012 through
2019, the total hours flown by piston-engine aircraft increased nine
percent from 13.2 million hours in 2012 to 14.4 million hours in
2019.69 70
---------------------------------------------------------------------------
\68\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 3: Primary and Actual Use. Table 3.2--General Aviation
and Part 135 Total Hours Flown by Actual Use 2008-2019 (Hours in
Thousands). Retrieved on Mar., 22, 2022 at https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/.
\69\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 3: Primary and Actual Use. Table 1.3--General Aviation
and Part 135 Total Hours Flown by Aircraft Type 2008-2019 (Hours in
Thousands). Retrieved on Dec., 27, 2021 at https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/.
\70\ In 2012, the FAA Aerospace Forecast projected a 0.03
percent increase in hours flown by the piston-engine aircraft fleet
for the period 2012 through 2032. FAA Aerospace Forecast Fiscal
Years 2012-2032. p. 53. Available at https://www.faa.gov/data_research/aviation/aerospace_forecasts/media/2012%20FAA%20Aerospace%20Forecast.pdf.
---------------------------------------------------------------------------
As noted earlier, the U.S. has a dense network of airports where
piston-engine aircraft operate, and a small subset of those airports
have air traffic control towers which collect daily counts of aircraft
operations at the facility (one takeoff or landing event is termed an
``operation''). These daily operations are provided by the FAA in the
Air Traffic Activity System (ATADS).\71\ The ATADS reports three
categories of airport operations that can be conducted by piston-engine
aircraft: Itinerant General Aviation, Local Civil, and Itinerant Air
Taxi. The sum of Itinerant General Aviation and Local Civil at a
facility is referred to as general aviation operations. Piston-engine
aircraft operations in these categories are not reported separately
from operations conducted by aircraft using other propulsion systems
(e.g., turboprop). Because piston-engine aircraft activity generally
comprises the majority of general aviation activity at an airport,
[[Page 62760]]
general aviation activity is often used as a surrogate measure for
understanding piston-engine activity.
---------------------------------------------------------------------------
\71\ See FAA's Air Traffic Activity Data. Available at https://aspm.faa.gov/opsnet/sys/airport.asp.
---------------------------------------------------------------------------
In order to understand the trend in airport-specific piston-engine
activity in the past ten years, we evaluated the trend in general
aviation activity. We calculated the average activity at each of the
airports in ATADS over three-year periods for the years 2010 through
2012 and for the years 2017 through 2019. We focused this trend
analysis on the airports in ATADS because these data are collected
daily at an airport-specific control tower (in contrast with annual
activity estimates provided at airports without control towers). There
were 513 airports in ATADS for which data were available to determine
annual average activity for both the 2010-2012 period and the 2017-2019
time period. The annual average operations by general aviation at each
of these airports in the period 2010 through 2012 ranged from 31 to
346,415, with a median of 34,368; the annual average operations by
general aviation in the period from 2017 through 2019 ranged from 2,370
to 396,554, with a median of 34,365. Of the 513 airports, 211 airports
reported increased general aviation activity over the period
evaluated.\72\ The increase in the average annual number of operations
by general aviation aircraft at these 211 facilities ranged from 151 to
136,872 (an increase of two percent and 52 percent, respectively).
---------------------------------------------------------------------------
\72\ Geidosch. Memorandum to Docket EPA-HQ-OAR-2022-0389. Past
Trends and Future Projections in General Aviation Activity and
Emissions. June 1, 2022. Docket ID EPA-HQ-2022-0389.
---------------------------------------------------------------------------
While national consumption of leaded avgas is forecast to decrease
three percent from 2026 to 2045, this change in fuel consumption is not
expected to occur uniformly across airports in the U.S. The FAA
produces the Terminal Area Forecast (TAF), which is the official
forecast of aviation activity for the 3,300 U.S. airports that are in
the NPIAS.\73\ For the 3,306 airports in the TAF, we compared the
average activity by general aviation at each airport from 2017-2019
with the FAA forecast for general aviation activity at those airports
in 2045. The FAA forecasts that activity by general aviation will
decrease at 234 of the airports in the TAF, remain the same at 1,960
airports, and increase at 1,112 of the airports. To evaluate the
magnitude of potential increases in activity for the same 513 airports
for which we evaluated activity trends in the past ten years, we
compared the 2017-2019 average general aviation activity at each of
these airports with the forecasted activity for 2045 in the TAF.\74\
The annual operations estimated for the 513 airports in 2045 ranges
from 2,914 to 427,821 with a median of 36,883. The TAF forecasts an
increase in activity at 442 of the 513 airports out to 2045, with the
increase in operations at those facilities ranging from 18 to 83,704
operations annually (an increase of 0.2 percent and 24 percent,
respectively).
---------------------------------------------------------------------------
\73\ FAA's TAF Fiscal Years 2020-2045 describes the forecast
method, data sources, and review process for the TAF estimates. The
documentation for the TAF is available at https://taf.faa.gov/Downloads/TAFSummaryFY2020-2045.pdf.
\74\ The TAF is prepared to assist the FAA in meeting its
planning, budgeting, and staffing requirements. In addition, state
aviation authorities and other aviation planners use the TAF as a
basis for planning airport improvements. The TAF is available on the
internet. The TAF database can be accessed at: https://taf.faa.gov.
---------------------------------------------------------------------------
2. Emissions of Lead From Piston-Engine Aircraft
This section describes the physical and chemical characteristics of
lead emitted by covered aircraft, and the national, state, county and
airport-specific annual inventories of these engine emissions of lead.
Information regarding lead emissions from motor vehicle engines
operating on leaded fuel is summarized in prior AQCDs for Lead, and the
2013 Lead ISA also includes information on lead emissions from piston-
engine aircraft.75 76 77 Lead is added to avgas in the form
of tetraethyl lead along with ethylene dibromide, both of which were
used in leaded gasoline for motor vehicles in the past. Therefore, the
summary of the science regarding emissions of lead from motor vehicles
presented in the 1997 and 1986 AQCDs for Lead is relevant to
understanding some of the properties of lead emitted from piston-engine
aircraft and the atmospheric chemistry these emissions are expected to
undergo. Recent studies relevant to understanding lead emissions from
piston-engine aircraft have also been published and are discussed here.
---------------------------------------------------------------------------
\75\ EPA (1977) AQC for Lead. EPA, Washington, DC, EPA-600/8-77-
017 (NTIS PB280411), 1977.
\76\ EPA (1986) AQC for Lead. EPA, Washington, DC, EPA-600/8-83/
028aF-dF (NTIS PB87142386), 1986.
\77\ EPA (2013) ISA for Lead. Section 2.2.2.1 ``Pb Emissions
from Piston-engine Aircraft Operating on Leaded Aviation Gasoline
and Other Non-road Sources.'' p. 2-10. EPA, Washington, DC, EPA/600/
R-10/075F, 2013.
---------------------------------------------------------------------------
a. Physical and Chemical Characteristics of Lead Emitted by Piston-
Engine Aircraft
As with motor vehicle engines, when leaded avgas is combusted, the
lead is oxidized to form lead oxide. In the absence of the ethylene
dibromide lead scavenger in the fuel, lead oxide can collect on the
valves and spark plugs, and if the deposits become thick enough, the
engine can be damaged. Ethylene dibromide reacts with the lead oxide,
converting it to brominated lead and lead oxybromides. These brominated
forms of lead remain volatile at high combustion temperatures and are
emitted from the engine along with the other combustion by-
products.\78\ Upon cooling to ambient temperatures these brominated
lead compounds are converted to particulate matter. The presence of
lead dibromide particles in the exhaust from a piston-engine aircraft
has been confirmed by Griffith (2020) and is the primary form of lead
emitted by engines operating on leaded fuel.\79\ In addition to lead
bromides, ammonium salts of other lead halides were also emitted by
motor vehicles and would be expected in the exhaust of piston-engine
aircraft.\80\
---------------------------------------------------------------------------
\78\ EPA (1986) AQC for Lead. EPA, Washington, DC, EPA-600/8-83/
028aF-dF (NTIS PB87142386), 1986.
\79\ Griffith 2020. Electron microscopic characterization of
exhaust particles containing lead dibromide beads expelled from
aircraft burning leaded gasoline. Atmospheric Pollution Research
11:1481-1486.
\80\ EPA (1986) AQC for Lead. Volume 2: Chapters 5 & 6. EPA,
Washington, DC, EPA-600/8-83/028aF-dF (NTIS PB87142386), 1986.
---------------------------------------------------------------------------
Uncombusted alkyl lead was also measured in the exhaust of motor
vehicles operating on leaded gasoline and is therefore likely to be
present in the exhaust from piston-engine aircraft.\81\ Alkyl lead is
the general term used for organic lead compounds and includes the lead
additive tetraethyl lead. Summarizing the available data regarding
emissions of alkyl lead from piston-engine aircraft, the 2013 Lead ISA
notes that lead in the exhaust that might be in organic form may
potentially be 20 percent (as an upper bound estimate).\82\ In
addition, tetraethyl lead is a highly volatile compound and therefore,
a portion of tetraethyl lead in fuel exposed to air will partition into
the vapor phase.\83\
---------------------------------------------------------------------------
\81\ EPA (2013) ISA for Lead. Table 2-1. ``Pb Compounds Observed
in the Environment.'' p. 2-8. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
\82\ EPA (2013) ISA for Lead. Section 2.2.2.1 ``Pb Emissions
from Piston-engine Aircraft Operating on Leaded-Aviation Gasoline
and Other Non-road Sources.'' p. 2-10. EPA, Washington, DC, EPA/600/
R-10/075F, 2013.
\83\ Memorandum to Docket EPA-HQ-OAR-2022-0389. Potential
Exposure to Non-exhaust Lead and Ethylene Dibromide. June 15, 2022.
Docket ID EPA-HQ-2022-0389.
---------------------------------------------------------------------------
Particles emitted by piston-engine aircraft are in the submicron
size range (less than one micron in diameter). The Swiss Federal Office
of Civil Aviation (FOCA) published a study of piston-engine aircraft
emissions including
[[Page 62761]]
measurements of lead.\84\ The Swiss FOCA reported the mean particle
diameter of particulate matter emitted by one single-engine piston-
powered aircraft ranged from 0.049 to 0.108 microns under different
power conditions (lead particles would be expected to be present, but
these particles were not separately identified in this study). The
particle number concentration ranged from 5.7x10\6\ to 8.6x10\6\
particles per cm\3\. The authors noted that these particle emission
rates are comparable to those from a typical diesel passenger car
engine without a particle filter.\85\ Griffith (2020) collected exhaust
particles from a piston-engine aircraft operating on leaded avgas and
examined the particles using electron microscopy. Griffith reported
that the mean diameter of particles collected in exhaust was 13
nanometers (0.013 microns) consisting of a 4 nanometer (0.004 micron)
lead dibromide particle surrounded by hydrocarbons.
---------------------------------------------------------------------------
\84\ Swiss FOCA (2007) Aircraft Piston Engine Emissions Summary
Report. 33-05-003 Piston Engine Emissions_Swiss FOCA_Summary.
Report_070612_rit. Available at https://www.bazl.admin.ch/bazl/en/home/specialists/regulations-and-guidelines/environment/pollutant-emissions/aircraft-engine-emissions/report-appendices-database-and-data-sheets.html.
\85\ Swiss FOCA (2007) Aircraft Piston Engine Emissions Summary
Report. 33-05-003 Piston Engine Emissions_Swiss FOCA_Summary.
Report_070612_rit. Section 2.2.3.a. Available at https://www.bazl.admin.ch/bazl/en/home/specialists/regulations-and-guidelines/environment/pollutant-emissions/aircraft-engine-emissions/report-appendices-database-and-data-sheets.html.
---------------------------------------------------------------------------
b. Inventory of Lead Emitted by Piston-Engine Aircraft
Lead emissions from covered aircraft are the largest single source
of lead to air in the U.S. in recent years, contributing over 50
percent of lead emissions to air starting in 2008 (Table 1).\86\ In
2017, approximately 470 tons of lead were emitted by engines in piston-
powered aircraft, which constituted 70 percent of the annual emissions
of lead to air in that year.\87\ Lead is emitted at and near thousands
of airports in the U.S. as described in Section II.A.1 of this
document. The EPA's method for developing airport-specific lead
estimates is described in the EPA's Advance Notice of Proposed
Rulemaking on Lead Emissions from Piston-Engine Aircraft Using Leaded
Aviation Gasoline \88\ and in the document titled ``Calculating Piston-
Engine Aircraft Airport Inventories for Lead for the 2008 National
Emissions Inventory.'' \89\ The EPA's National Emissions Inventory
(NEI) reports airport estimates of lead emissions as well as estimates
of lead emitted in-flight, which are allocated to states based on the
fraction of piston-engine aircraft activity estimated for each state.
These inventory data are briefly summarized here at the state, county,
and airport level.\90\
---------------------------------------------------------------------------
\86\ The lead inventories for 2008, 2011 and 2014 are provided
in the U.S. EPA (2018b) Report on the Environment Exhibit 2.
Anthropogenic lead emissions in the U.S. Available at https://cfpub.epa.gov/roe/indicator.cfm?i=13#2.
\87\ EPA 2017 NEI. Available at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data.
\88\ Advance Notice of Proposed Rulemaking on Lead Emissions
from Piston-Engine Aircraft Using Leaded Aviation Gasoline. 75 FR
2440 (April 28, 2010).
\89\ Airport lead annual emissions data used were reported in
the 2017 NEI. Available at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data. The methods
used to develop these inventories are described in EPA (2010)
Calculating Piston-Engine Aircraft Airport Inventories for Lead for
the 2008 NEI. EPA, Washington, DC, EPA-420-B-10-044, 2010. (Also
available in the docket for this action, EPA-HQ-OAR-2022-0389).
\90\ The 2017 NEI utilized 2014 aircraft activity data to
develop airport-specific lead inventories. Details can be found on
page 3-17 of the document located here: https://www.epa.gov/sites/default/files/2021-02/documents/nei2017_tsd_full_jan2021.pdf#page=70&zoom=100,68,633.
Table 1--Piston-Engine Emissions of Lead to Air
----------------------------------------------------------------------------------------------------------------
2008 2011 2014 2017
----------------------------------------------------------------------------------------------------------------
Piston-engine emissions of lead to air, tons.... 560 490 460 470
Total U.S. lead emissions, tons................. 950 810 720 670
Piston-engine emissions as a percent of the 59% 60% 64% 70%
total U.S. lead inventory......................
----------------------------------------------------------------------------------------------------------------
At the state level, the EPA estimates of lead emissions from
piston-engine aircraft range from 0.3 tons (Rhode Island) to 50.5 tons
(California), 47 percent of which is emitted in the landing and takeoff
cycle and 53 percent of which the EPA estimates is emitted in-flight,
outside the landing and takeoff cycle.\91\ Among the counties in the
U.S. where the EPA estimates engine emissions of lead from covered
aircraft, lead inventories range from 0.00005 tons per year to 4.1 tons
per year and constitute the only source of air-related lead in 1,140
counties (the county estimates of lead emissions include the lead
emitted during the landing and takeoff cycle and not lead emitted in-
flight).\92\ In the counties where engine emissions of lead from
aircraft are the sole source of lead to these estimates, annual lead
emissions from the landing and takeoff cycle ranged from 0.00015 to
0.74 tons. Among the 1,872 counties in the U.S. with multiple sources
of lead, including engine emission from covered aircraft, the
contribution of aircraft engine emissions ranges from 0.0006 to 0.26
tons, comprising 0.0065 to 99.98 percent of the county total,
respectively.
---------------------------------------------------------------------------
\91\ Lead emitted in-flight is assigned to states based on their
overall fraction of total piston-engine aircraft operations. The
state-level estimates of engine emissions of lead include both lead
emitted in the landing and takeoff cycle as well as lead emitted in-
flight. The method used to develop these estimates is described in
EPA (2010) Calculating Piston-Engine Aircraft Airport Inventories
for Lead for the 2008 NEI, available here: https://nepis.epa.gov/Exe/ZyPDF.cgi/P1009I13.PDF?Dockey=P1009I13.PDF.
\92\ Airport lead annual emissions data used were reported in
the 2017 NEI. Available at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data. In addition
to the triennial NEI, the EPA collects from state, local, and Tribal
air agencies point source data for larger sources every year (see
https://www.epa.gov/air-emissions-inventories/air-emissions-reporting-requirements-aerr for specific emissions thresholds).
While these data are not typically published as a new NEI, they are
available publicly upon request and are also included in https://www.epa.gov/air-emissions-modeling/emissions-modeling-platforms that
are created for years other than the triennial NEI years. County
estimates of lead emissions from non-aircraft sources used in this
action are from the 2019 inventory. There are 3,012 counties and
statistical equivalent areas where EPA estimates engine emissions of
lead occur.
---------------------------------------------------------------------------
The EPA estimates that among the approximately 20,000 airports in
the U.S., airport lead inventories range from 0.00005 tons per year to
0.9 tons per year.\93\ In 2017, the EPA's NEI includes 638 airports
where the EPA estimates engine emissions of lead from covered aircraft
were 0.1 ton or more of lead annually. Using the FAA's forecasted
activity in 2045 for the approximately 3,300 airports in the NPIAS (as
described in Section II.A.1 of this document), the EPA estimates
airport-specific inventories may range from 0.00003 tons to 1.28 tons
of lead (median of 0.03 tons), with 656 airports
[[Page 62762]]
estimated to have inventories above 0.1 tons in 2045.\94\
---------------------------------------------------------------------------
\93\ See EPA lead inventory data available at https://www.epa.gov/air-emissions-modeling/emissions-modeling-platforms.
\94\ EPA used the method describe in EPA (2010) Calculating
Piston-Engine Aircraft Airport Inventories for Lead for the 2008 NEI
to estimate airport lead inventories in 2045. This document is
available here: https://nepis.epa.gov/Exe/ZyPDF.cgi/P1009I13.PDF?Dockey=P1009I13.PDF.
---------------------------------------------------------------------------
We estimate that piston-engine aircraft have consumed approximately
38.6 billion gallons of leaded avgas in the U.S. since 1930, excluding
military aircraft use of this fuel, emitting approximately 113,000 tons
of lead to the air.\95\
---------------------------------------------------------------------------
\95\ Geidosch. Memorandum to Docket EPA-HQ-OAR-2022-0389. Lead
Emissions from the use of Leaded Aviation Gasoline from 1930 through
2020. June 1, 2022. Docket ID EPA-HQ-2022-0389.
---------------------------------------------------------------------------
3. Concentrations of Lead in Air Attributable to Emissions From Piston-
Engine Aircraft
In this section, we describe the concentrations of lead in air
resulting from emissions of lead from covered aircraft. Air quality
monitoring and modeling studies for lead at and near airports have
identified elevated concentrations of lead in air from piston-engine
aircraft exhaust at, and downwind of, airports where these aircraft are
active.96 97 98 99
100 101 This section provides a summary of the
literature regarding the local-scale impact of aircraft emissions of
lead on concentrations of lead at and near airports, with specific
focus on the results of air monitoring for lead that the EPA required
at a subset of airports and an analysis conducted by the EPA to
estimate concentrations of lead at 13,000 airports in the U.S., titled
``Model-extrapolated Estimates of Airborne Lead Concentrations at U.S.
Airports.'' 102 103
---------------------------------------------------------------------------
\96\ Carr et. al., 2011. Development and evaluation of an air
quality modeling approach to assess near-field impacts of lead
emissions from piston-engine aircraft operating on leaded aviation
gasoline. Atmospheric Environment, 45 (32), 5795-5804. DOI: https://dx.doi.org/10.1016/j.atmosenv.2011.07.017.
\97\ Feinberg et. al., 2016. Modeling of Lead Concentrations and
Hot Spots at General Aviation Airports. Journal of the
Transportation Research Board, No. 2569, Transportation Research
Board, Washington, DC, pp. 80-87. DOI: 10.3141/2569-09.
\98\ Municipality of Anchorage (2012). Merrill Field Lead
Monitoring Report. Municipality of Anchorage Department of Health
and Human Services. Anchorage, Alaska. Available at https://www.muni.org/Departments/health/Admin/environment/AirQ/Documents/Merrill%20Field%20Lead%20Monitoring%20Study_2012/Merrill%20Field%20Lead%20Study%20Report%20-%20final.pdf.
\99\ Environment Canada (2000) Airborne Particulate Matter, Lead
and Manganese at Buttonville Airport. Toronto, Ontario, Canada:
Conor Pacific Environmental Technologies for Environmental
Protection Service, Ontario Region.
\100\ Fine et. al., 2010. General Aviation Airport Air
Monitoring Study. South Coast Air Quality Management District.
Available at https://www.aqmd.gov/docs/default-source/air-quality/air-quality-monitoring-studies/general-aviation-study/study-of-air-toxins-near-van-nuys-and-santa-monica-airport.pdf.
\101\ Lead emitted from piston-engine aircraft in the
particulate phase would also be measured in samples collected to
evaluate total ambient PM2.5 concentrations.
\102\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. EPA, Washington, DC, EPA-420-R-20-
003, 2020. Available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG52.pdf. EPA responses to peer review comments
on the report are available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YIWD.pdf. These documents are also available in
the docket for this action (Docket EPA-HQ-OAR-2022-0389).
\103\ EPA (2022) Technical Support Document (TSD) for the EPA's
Proposed Finding that Lead Emissions from Aircraft Engines that
Operate on Leaded Fuel Cause or Contribute to Air Pollution that May
Reasonably Be Anticipated to Endanger Public Health and Welfare.
EPA, Washington, DC, EPA-420-R-22-025, 2022. Available in the docket
for this action.
---------------------------------------------------------------------------
Gradient studies evaluate how lead concentrations change with
distance from an airport where piston-engine aircraft operate. These
studies indicate that concentrations of lead in air are estimated to be
one to two orders of magnitude higher at locations proximate to
aircraft emissions, compared to nearby locations not impacted by a
source of lead air emissions (concentrations for periods of
approximately 18 hours to three-month averages).104
105 106 107 108
109 The magnitude of lead concentrations at and near
airports is highly influenced by the amount of aircraft activity (i.e.,
the number of take-off and landing operations, particularly if
concentrated at one runway) and the time spent by aircraft in specific
modes of operation. The most significant emissions in terms of ground-
based activity, and therefore ground-level concentrations of lead in
air, occur near the areas with greatest fuel consumption where the
aircraft are stationary and running.110 111
112 For piston-engine aircraft these areas are most commonly
locations in which pilots conduct engine tests during run-up operations
prior to take-off (e.g., magneto checks during the run-up operation
mode). Run-up operations are conducted while the brakes are engaged so
the aircraft is stationary and are often conducted adjacent to the
runway end from which the aircraft will take off. Additional modes of
operation by piston-engine aircraft, such as taxiing or idling near the
runway, may result in additional hotspots of elevated lead
concentration (e.g., start-up and idle, maintenance run-up).\113\
---------------------------------------------------------------------------
\104\ These studies report monitored or modeled data for
averaging times ranging from approximately 18 hours to three-month
averages.
\105\ Carr et. al., 2011. Development and evaluation of an air
quality modeling approach to assess near-field impacts of lead
emissions from piston-engine aircraft operating on leaded aviation
gasoline. Atmospheric Environment, 45 (32), 5795-5804. DOI: https://dx.doi.org/10.1016/j.atmosenv.2011.07.017.
\106\ Heiken et. al., 2014. Quantifying Aircraft Lead Emissions
at Airports. ACRP Report 133. Available at https://www.nap.edu/catalog/22142/quantifying-aircraft-lead-emissions-at-airports.
\107\ Hudda et. al., 2022. Substantial Near-Field Air Quality
Improvements at a General Aviation Airport Following a Runway
Shortening. Environmental Science & Technology. DOI: 10.1021/
acs.est.1c06765.
\108\ Fine et. al., 2010. General Aviation Airport Air
Monitoring Study. South Coast Air Quality Management District.
Available at https://www.aqmd.gov/docs/default-source/air-quality/air-quality-monitoring-studies/general-aviation-study/study-of-air-toxins-near-van-nuys-and-santa-monica-airport.pdf.
\109\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. EPA, Washington, DC, EPA-420-R-20-
003, 2020.
\110\ EPA (2010) Development and Evaluation of an Air Quality
Modeling Approach for Lead Emissions from Piston-Engine Aircraft
Operating on Leaded Aviation Gasoline. EPA, Washington, DC, EPA-420-
R-10-007, 2010. https://nepis.epa.gov/Exe/ZyPDF.cgi/P1007H4Q.PDF?Dockey=P1007H4Q.PDF.
\111\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. EPA, Washington, DC, EPA-420-R-20-
003, 2020. EPA responses to peer review comments on the report are
available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YIWD.pdf.
\112\ Feinberg et. al., 2016. Modeling of Lead Concentrations
and Hot Spots at General Aviation Airports. Journal of the
Transportation Research Board, No. 2569, Transportation Research
Board, Washington, DC, pp. 80-87. DOI: 10.3141/2569-09.
\113\ Feinberg et. al., 2016. Modeling of Lead Concentrations
and Hot Spots at General Aviation Airports. Journal of the
Transportation Research Board, No. 2569, Transportation Research
Board, Washington, DC, pp. 80-87. DOI: 10.3141/2569-09.
---------------------------------------------------------------------------
The lead NAAQS was revised in 2008.\114\ The 2008 decision revised
the level, averaging time and form of the standards to establish the
current primary and secondary standards, which are both 0.15 micrograms
per cubic meter of air, in terms of consecutive three-month average of
lead in total suspended particles.\115\ In conjunction with
strengthening the lead NAAQS in 2008, the EPA enhanced the existing
lead monitoring network by requiring monitors to be placed in areas
with sources such as industrial facilities and airports with estimated
lead emissions of 1.0 ton or more per year. Lead monitoring was
conducted at two airports following from these requirements (Deer
Valley Airport, AZ and the Van Nuys Airport, CA). In 2010, the EPA made
further revisions to the monitoring requirements such that state and
local air quality agencies are now required to monitor near industrial
facilities with estimated lead emissions of 0.50 tons or more per year
and at airports with estimated emissions of 1.0
[[Page 62763]]
ton or more per year.\116\ As part of this 2010 requirement to expand
lead monitoring, the EPA also required a one-year monitoring study of
15 additional airports with estimated lead emissions between 0.50 and
1.0 ton per year in an effort to better understand how these emissions
affect concentrations of lead in the air at and near airports. Further,
to help evaluate airport characteristics that could lead to ambient
lead concentrations that approach or exceed the lead NAAQS, airports
for this one-year monitoring study were selected based on factors such
as the level of piston-engine aircraft activity and the predominant use
of one runway due to wind patterns.
---------------------------------------------------------------------------
\114\ 73 FR 66965 (Nov. 12, 2008).
\115\ 40 CFR 50.16 (Nov. 12, 2008).
\116\ 75 FR 81226 (Dec. 27, 2010).
---------------------------------------------------------------------------
As a result of these requirements, state and local air authorities
collected and certified lead concentration data for at least one year
at 17 airports with most monitors starting in 2012 and generally
continuing through 2013. The data presented in Table 2 are based on the
certified data for these sites and represent the maximum concentration
monitored in a rolling three-month average for each location.
117 118
---------------------------------------------------------------------------
\117\ EPA (2015) Program Overview: Airport Lead Monitoring. EPA,
Washington, DC, EPA-420-F-15-003, 2015. Available at: https://nepis.epa.gov/Exe/ZyPDF.cgi/P100LJDW.PDF?Dockey=P100LJDW.PDF.
\118\ EPA (2022) Technical Support Document (TSD) for the EPA's
Proposed Finding that Lead Emissions from Aircraft Engines that
Operate on Leaded Fuel Cause or Contribute to Air Pollution that May
Reasonably Be Anticipated to Endanger Public Health and Welfare.
EPA, Washington, DC, EPA-420-R-22-025, 2022. Available in the docket
for this action.
Table 2--Lead Concentrations Monitored at 17 Airports in the U.S.
------------------------------------------------------------------------
Lead design
Airport, State value,\119\
[mu]g/m\3\
------------------------------------------------------------------------
Auburn Municipal Airport, WA............................... 0.06
Brookhaven Airport, NY..................................... 0.03
Centennial Airport, CO..................................... 0.02
Deer Valley Airport, AZ.................................... 0.04
Gillespie Field, CA........................................ 0.07
Harvey Field, WA........................................... 0.02
McClellan-Palomar Airport, CA.............................. 0.17
Merrill Field, AK.......................................... 0.07
Nantucket Memorial Airport, MA............................. 0.01
Oakland County International Airport, MI................... 0.02
Palo Alto Airport, CA...................................... 0.12
Pryor Field Regional Airport, AL........................... 0.01
Reid-Hillview Airport, CA.................................. 0.10
Republic Airport, NY....................................... 0.01
San Carlos Airport, CA..................................... 0.33
Stinson Municipal, TX...................................... 0.03
Van Nuys Airport, CA....................................... 0.06
------------------------------------------------------------------------
Monitored lead concentrations violated the lead NAAQS at two
airports in 2012: the McClellan-Palomar Airport and the San Carlos
Airport. At both of these airports, monitors were located in close
proximity to the area at the end of the runway most frequently used for
pre-flight safety checks (i.e., run-up). Alkyl lead emitted by piston-
engine aircraft would be expected to partition into the vapor phase and
would not be collected by the monitoring conducted in this study, which
is designed to quantitatively collect particulate forms of lead.\120\
---------------------------------------------------------------------------
\119\ A design value is a statistic that summarizes the air
quality data for a given area in terms of the indicator, averaging
time, and form of the standard. Design values can be compared to the
level of the standard and are typically used to designate areas as
meeting or not meeting the standard and assess progress towards
meeting the NAAQS.
\120\ As noted earlier, when summarizing the available data
regarding emissions of alkyl lead from piston-engine aircraft, the
2013 Lead ISA notes that an upper bound estimate of lead in the
exhaust that might be in organic form may potentially be 20 percent
(2013 Lead ISA, p. 2-10). Organic lead in engine exhaust would be
expected to influence receptors within short distances of the point
of emission from piston-engine aircraft. Airports with large flight
schools and/or facilities with substantial delays for aircraft
queued for takeoff could experience higher concentrations of alkyl
lead in the vicinity of the aircraft exhaust.
---------------------------------------------------------------------------
Airport lead monitoring and modeling studies have identified the
sharp decrease in lead concentrations with distance from the run-up
area and therefore the importance of considering monitor placement
relative to the run-up area when evaluating the maximum impact location
attributable to lead emissions from piston-engine aircraft. The
monitoring data in Table 2 reflect differences in monitor placement
relative to the run-up area as well as other factors; this study also
provided evidence that air lead concentrations at and downwind from
airports could be influenced by factors such as the use of more than
one run-up area, wind speed, and the number of operations conducted by
single- versus twin-engine aircraft.\121\
---------------------------------------------------------------------------
\121\ The data in Table 2 represent concentrations measured at
one location at each airport and monitors were not consistently
placed in close proximity to the run-up areas. As described in
Section II.A.3, monitored concentrations of lead in air near
airports are highly influenced by proximity of the monitor to the
run-up area. In addition to monitor placement, there are individual
airport factors that can influence lead concentrations (e.g., the
use of multiple run-up areas at an airport, fleet composition, and
wind speed). The monitoring data reported in Table 2 reflect a range
of lead concentrations indicative of the location at which
measurements were made and the specific operations at an airport.
---------------------------------------------------------------------------
The EPA recognized that the airport lead monitoring study provided
a small sample of the potential locations where emissions of lead from
piston-engine aircraft could potentially cause concentrations of lead
in ambient air to exceed the lead NAAQS. Because we anticipated that
additional airports and conditions could lead to exceedances of the
lead NAAQS at and near airports where piston-engine aircraft operate,
and in order to understand the range of lead concentrations at airports
nationwide, we developed an analysis of 13,000 airports in the peer-
reviewed report titled, ``Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports.'' \122 123\ This report provides
estimated ranges of lead concentrations that may occur at and near
airports where leaded avgas is used. The study extrapolated modeling
results from one airport to estimate air lead concentrations at the
maximum impact area near the run-up location for over 13,000 U.S.
airports.\124\ The model-extrapolated lead estimates in this study
indicate that some additional U.S. airports may have air lead
concentrations above the NAAQS at this area of maximum impact. The
report also indicates that, at the levels of activity analyzed at the
13,000 airports, estimated lead concentrations decrease to below the
standard within 50 meters from the location of highest concentration.
---------------------------------------------------------------------------
\122\ EPA (2020) Model-Extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. EPA, Washington, DC, EPA-420-R-20-
003, 2020.
\123\ EPA (2022) Technical Support Document (TSD) for the EPA's
Proposed Finding that Lead Emissions from Aircraft Engines that
Operate on Leaded Fuel Cause or Contribute to Air Pollution that May
Reasonably Be Anticipated to Endanger Public Health and Welfare.
EPA, Washington, DC, EPA-420-R-22-025, 2022. Available in the docket
for this action.
\124\ In this study, the EPA defined the maximum impact site as
15 meters downwind of the tailpipe of an aircraft conducting run-up
operations in the area designated for these operations at a runway
end. The maximum impact area was defined as approximately 50 meters
surrounding the maximum impact site.
---------------------------------------------------------------------------
To estimate the potential ranges of lead concentrations at and
downwind of the anticipated area of highest concentration at airports
in the U.S., the relationship between piston-engine aircraft activity
and lead concentration at and downwind of the maximum impact site at
one airport was applied to piston-engine aircraft activity estimates
for each U.S. airport.\125\ This approach for conducting a nationwide
analysis of airports was selected due to the impact of piston-engine
aircraft run-up
[[Page 62764]]
operations on ground-level lead concentrations, which creates a maximum
impact area that is expected to be generally consistent across
airports. Specifically, these aircraft consistently take off into the
wind and typically conduct run-up operations immediately adjacent to
the take-off runway end, and thus, modeling lead concentrations from
this source is constrained by variation in a few key parameters. These
parameters include: (1) Total amount of piston-engine aircraft
activity, (2) the proportion of activity conducted at one runway end,
(3) the proportion of activity conducted by multi-piston-engine
aircraft, (4) the duration of run-up operations, (5) the concentration
of lead in avgas, (6) wind speed at the model airport relative to the
extrapolated airport, and (7) additional meteorological, dispersion
model, or operational parameters. These parameters were evaluated
through sensitivity analyses as well as quantitative or qualitative
uncertainty analyses. To generate robust concentration estimates, the
EPA evaluated these parameters, conducted wind-speed correction of
extrapolated estimates, and used airport-specific information regarding
airport layout and prevailing wind directions for the 13,000
airports.\126\
---------------------------------------------------------------------------
\125\ Prior to this model extrapolation study, the EPA developed
and evaluated an air quality modeling approach (this study is
available here: https://nepis.epa.gov/Exe/ZyPDF.cgi/P1007H4Q.PDF?Dockey=P1007H4Q.PDF), and subsequently applied the
approach to a second airport and again performed an evaluation of
the model output using air monitoring data (this second study is
available here: https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG52.pdf).
\126\ EPA (2022) Technical Support Document (TSD) for the EPA's
Proposed Finding that Lead Emissions from Aircraft Engines that
Operate on Leaded Fuel Cause or Contribute to Air Pollution that May
Reasonably Be Anticipated to Endanger Public Health and Welfare.
EPA, Washington, DC, EPA-420-R-22-025, 2022. Available in the docket
for this action.
---------------------------------------------------------------------------
Results of this national analysis show that model-extrapolated
three-month average lead concentrations in the maximum impact area may
potentially exceed the lead NAAQS at airports with activity ranging
from 3,616-26,816 Landing and Take-Off events (LTOs) in a three-month
period.\127\ The lead concentration estimates from this model-
extrapolation approach account for lead engine emissions from aircraft
only, and do not include other sources of air-related lead. The broad
range in LTOs that may lead to concentrations of lead exceeding the
lead NAAQS is due to the piston-engine aircraft fleet mix at individual
airports such that airports where the fleet is dominated by twin-engine
aircraft would potentially reach concentrations of lead exceeding the
lead NAAQS with fewer LTOs compared with airports where single-engine
aircraft dominate the piston-engine fleet.\128\ Model-extrapolated
three-month average lead concentrations from aircraft engine emissions
were estimated to extend to a distance of at least 500 meters from the
maximum impact area at airports with activity ranging from 1,275-4,302
LTOs in that three-month period.\129\ In a separate modeling analysis
at an airport at which hundreds of take-off and landing events by
piston-engine aircraft occur per day, the EPA found that modeled 24-
hour concentrations of lead were estimated above background extending
almost 1,000 meters downwind from the runway.\130\
---------------------------------------------------------------------------
\127\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. Table 6. p. 53. EPA, Washington,
DC, EPA-420-R-20-003, 2020.
\128\ See methods used in EPA (2020) Model-extrapolated
Estimates of Airborne Lead Concentrations at U.S. Airports. Table 2.
p.23. EPA, Washington, DC, EPA-420-R-20-003, 2020.
\129\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports, Table 6. p.53. EPA, Washington, DC,
EPA-420-R-20-003, 2020.
\130\ Carr et. al., 2011. Development and evaluation of an air
quality modeling approach to assess near-field impacts of lead
emissions from piston-engine aircraft operating on leaded aviation
gasoline. Atmospheric Environment 45: 5795-5804.
---------------------------------------------------------------------------
Model-extrapolated estimates of lead concentrations in the EPA
report ``Model-extrapolated Estimates of Airborne Lead Concentrations
at U.S. Airports'' were compared with monitored values and show general
agreement, suggesting that the extrapolation method presented in this
report provides reasonable estimates of the range in concentrations of
lead in air attributable to three-month activity periods of piston-
engine aircraft at airports. The assessment included detailed
evaluation of the potential impact of run-up duration, the
concentration of lead in avgas, and the impact of meteorological
parameters on model-extrapolated estimates of lead concentrations
attributable to engine emissions of lead from piston-powered aircraft.
Additionally, this study included a range of sensitivity analyses as
well as quantitative and qualitative uncertainty analyses. The EPA
invites comment on the approach used in this model-extrapolation
analysis.
The EPA's model-extrapolation analysis of lead concentrations from
engine emissions resulting from covered aircraft found that the lowest
annual airport emissions of lead estimated to result in air lead
concentrations approaching or potentially exceeding the NAAQS was 0.1
tons per year. There are key pieces of airport-specific data that are
needed to fully evaluate the potential for piston-engine aircraft
operating at an airport to cause concentrations of lead in the air to
exceed the lead NAAQS, and the EPA's report ``Model-extrapolated
Estimates of Airborne Lead Concentrations at U.S. Airports'' provides
quantitative and qualitative analyses of these factors.\131\ The EPA's
estimate of airports that have annual lead inventories of 0.1 ton or
more are illustrative of, and provide one approach for an initial
screening evaluation of locations where engine emissions of lead from
aircraft increase localized lead concentrations in air. Airport-
specific assessments would be needed to determine the magnitude of the
potential range in lead concentrations at and downwind of each
facility.
---------------------------------------------------------------------------
\131\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. Table 6. p.53. EPA, Washington, DC,
EPA-420-R-20-003, 2020. EPA responses to peer review comments on the
report are available here: https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YIWD.pdf.
---------------------------------------------------------------------------
As described in Section II.A.1 of this document, the FAA forecasts
0.9 percent decreases in piston-engine aircraft activity out to 2041,
however these decreases are not projected to occur uniformly across
airports. Among the more than 3,300 airports in the FAA TAF, the FAA
forecasts both decreases and increases in general aviation, which is
largely comprised of piston-engine aircraft. If the current conditions
on which the forecast is based persist, then lead concentrations in the
air may increase at the airports where general aviation activity is
forecast to increase.
In addition to airport-specific modeled estimates of lead
concentrations, the EPA also provides annual estimates of lead
concentrations for each census tract in the U.S. as part of the Air
Toxics Screening Assessment (AirToxScreen).\132\ The census tract
concentrations are averages of the area-weighted census block
concentrations within the tract. Lead concentrations reported in the
AirToxScreen are based on emissions estimates from anthropogenic and
natural sources, including aircraft engine emissions.\133\ The 2017
AirToxScreen provides lead concentration estimates in air for 73,449
[[Page 62765]]
census tracts in the U.S.\134\ Lead emissions from piston-engine
aircraft comprised more than 50 percent of these census block area-
weighted lead concentrations in over half of the census tracts, which
included tracts in all 50 states, as well as Puerto Rico and the Virgin
Islands.
---------------------------------------------------------------------------
\132\ See EPA's 2017 AirToxScreen. Available at https://www.epa.gov/AirToxScreen.
\133\ These concentration estimates are not used for comparison
to the level of the Lead NAAQS due to different temporal averaging
times and underlying assumptions in modeling. The AirToxScreen
estimates are provided to help state, local and Tribal air agencies
and the public identify which pollutants, emission sources and
places they may wish to study further to better understand potential
risks to public health from air toxics. There are uncertainties
inherent in these estimates described by the EPA, some of which are
relevant to these estimates of lead concentrations; however, these
estimates provide perspective on the potential influence of piston-
engine emissions of lead on air quality. See https://www.epa.gov/AirToxScreen/airtoxscreen-limitations.
\134\ As airports are generally in larger census blocks within a
census tract, concentrations for airport blocks dominate the area-
weighted average in cases where an airport is the predominant lead
emissions source in a census tract.
---------------------------------------------------------------------------
4. Fate and Transport of Emissions of Lead From Piston-Engine Aircraft
This section summarizes the chemical transformation that piston-
engine aircraft lead emissions are anticipated to undergo in the
atmosphere and describes what is known about the deposition of piston-
engine aircraft lead, and potential impacts on soil, food, and aquatic
environments.
a. Atmospheric Chemistry and Transport of Emissions of Lead From
Piston-Engine Aircraft
Lead emitted by piston-engine aircraft can have impacts in the
local environment and, due to their small size (i.e., typically less
than one micron in diameter),\135 136\ lead-bearing particles emitted
by piston engines may disperse widely in the environment. However, lead
emitted during the landing and takeoff cycle, particularly during
ground-based operations such as start-up, idle, preflight run-up
checks, taxi and the take-off roll on the runway, may deposit to the
local environment and/or infiltrate into buildings.\137\ Depending on
ambient conditions (e.g., ozone and hydroxyl concentrations in the
atmosphere), alkyl lead may exist in the atmosphere for hours to days
\138\ and may therefore be transported off airport property into nearby
communities.
---------------------------------------------------------------------------
\135\ Swiss FOCA (2007) Aircraft Piston Engine Emissions Summary
Report. 33-05-003 Piston Engine Emissions_Swiss FOCA_Summary.
Report_070612_rit. Available at https://www.bazl.admin.ch/bazl/en/home/specialists/regulations-and-guidelines/environment/pollutant-emissions/aircraft-engine-emissions/report-appendices-database-and-data-sheets.html.
\136\ Griffith 2020. Electron microscopic characterization of
exhaust particles containing lead dibromide beads expelled from
aircraft burning leaded gasoline. Atmospheric Pollution Research
11:1481-1486.
\137\ EPA (2013) ISA for Lead. Section 1.3. ``Exposure to
Ambient Pb.'' p. 1-11. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\138\ EPA (2006) AQC for Lead. Section E.6. p. 2-5. EPA,
Washington, DC, EPA/600/R-5/144aF, 2006.
---------------------------------------------------------------------------
Lead halides emitted by motor vehicles operating on leaded fuel
were reported to undergo compositional changes upon cooling and mixing
with the ambient air as well as during transport, and we would
anticipate lead bromides emitted by piston-engine aircraft to behave
similarly in the atmosphere. The water-solubility of these lead-bearing
particles was reported to be higher for the smaller lead-bearing
particles.\139\ Lead halides emitted in motor vehicle exhaust were
reported to break down rapidly in the atmosphere via redox reactions in
the presence of atmospheric acids.\140\ Tetraethyl lead has an
atmospheric residence time ranging from a few hours to a few days.
Tetraethyl lead reacts with the hydroxyl radical in the gas phase to
form a variety of products that include ionic trialkyl lead, dialkyl
lead and metallic lead. Trialkyl lead is slow to react with the
hydroxyl radical and is quite persistent in the atmosphere.\141\
---------------------------------------------------------------------------
\139\ EPA (1977) AQC for Lead. Section 6.2.2.1. EPA, Washington,
DC, EPA-600/8-77-017, 1977.
\140\ EPA (2006) AQC for Lead. Section E.6. EPA, Washington, DC,
EPA/600/R-5/144aF, 2006.
\141\ EPA (2006) AQC for Lead. Section 2. EPA, Washington, DC,
EPA/600/R-5/144aF, 2006.
---------------------------------------------------------------------------
b. Deposition of Lead Emissions From Piston-Engine Aircraft and Soil
Lead Concentrations to Which Piston-Engine Aircraft May Contribute
Lead is removed from the atmosphere and deposited on soil, into
aquatic systems and on other surfaces via wet or dry deposition.\142\
Meteorological factors (e.g., wind speed, convection, rain, humidity)
influence local deposition rates. With regard to deposition of lead
from aircraft engine emissions, the EPA modeled the deposition rate for
aircraft lead emissions at one airport in a temperate climate in
California with dry summer months. In this location, the average lead
deposition rate from aircraft emissions of lead was 0.057 milligrams
per square meter per year.\143\
---------------------------------------------------------------------------
\142\ EPA (2013) ISA for Lead. Section 1.2.1. ``Sources, Fate
and Transport of Ambient Pb;'' p. 1-6; and Section 2.3. ``Fate and
Transport of Pb.'' p. 2-24 through 2-25. EPA, Washington, DC, EPA/
600/R-10/075F, 2013.
\143\ Memorandum to Docket EPA-HQ-OAR-2022-0389. Deposition of
Lead Emitted by Piston-engine Aircraft. June 15, 2022. Docket ID
EPA-HQ-2022-0389.
---------------------------------------------------------------------------
Studies summarized in the 2013 Lead ISA suggest that soil is a
reservoir for contemporary and historical emissions of lead to
air.\144\ Once deposited to soil, lead can be absorbed onto organic
material, can undergo chemical and physical transformation depending on
a number of factors (e.g., pH of the soil and the soil organic
content), and can participate in further cycling through air or other
media.\145\ The extent of atmospheric deposition of lead from aircraft
engine emissions would be expected to depend on a number of factors
including the size of the particles emitted (smaller particles, such as
those in aircraft emissions, have lower settling velocity and may
travel farther distances before being deposited compared with larger
particles), the temperature of the exhaust (the high temperature of the
exhaust creates plume buoyancy), as well as meteorological factors
(e.g., wind speed, precipitation rates). As a result of the size of the
lead particulate matter emitted from piston-engine aircraft and as a
result of these emissions occurring at various altitudes, lead emitted
from these aircraft may distribute widely through the environment.\146\
Murphy et al. (2008) reported weekend increases in ambient lead
monitored at remote locations in the U.S. that the authors attributed
to weekend increases in piston-engine powered general aviation
activity.\147\
---------------------------------------------------------------------------
\144\ EPA (2013) ISA for Lead. Section 2.6.1. ``Soils.'' p. 2-
118. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\145\ EPA (2013) ISA for Lead. Chapter 6. ``Ecological Effects
of Pb.'' p. 6-57. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\146\ Murphy et al., 2008. Weekly patterns of aerosol in the
United States. Atmospheric Chemistry and Physics. 8:2729-2739.
\147\ Lead concentrations collected as part of the Interagency
Monitoring of Protected Visual Environments (IMPROVE) network and
the National Oceanic and Atmospheric Administration (NOAA)
monitoring sites.
---------------------------------------------------------------------------
Heiken et al. (2014) assessed air lead concentrations potentially
attributable to resuspended lead that previously deposited onto soil
relative to air lead concentrations resulting directly from aircraft
engine emissions.\148\ Based on comparisons of lead concentrations in
total suspended particulate (TSP) and fine particulate matter
(PM2.5) measured at the three airports, coarse particle lead
was observed to account for about 20-30 percent of the lead found in
TSP. The authors noted that based on analysis of lead isotopes present
in the air samples collected at these airports, the original source of
the lead found in the coarse particle range appeared to be from
aircraft exhaust emissions of lead that previously deposited to soil
and were resuspended by wind or aircraft-induced turbulence. Results
from lead isotope analysis in soil samples collected at the same three
airports led the authors to conclude that lead emitted from piston-
engine aircraft was not the dominant source of lead in soil in the
samples measured at the airports they studied. The authors note the
[[Page 62766]]
complex history of topsoil can create challenges in understanding the
extent to which aircraft lead emissions impact soil lead concentrations
at and near airports (e.g., the source of topsoil can change as a
result of site renovation, construction, landscaping, natural events
such as wildfire and hurricanes, and other activities). Concentrations
of lead in soil at and near airports servicing piston-engine aircraft
have been measured using a range of
approaches.149 150 151 152 153 154 Kavouras et al. (2013)
collected soil samples at three airports and reported that construction
at an airport involving removal and replacement of topsoil complicated
interpretation of the findings at that airport and that the number of
runways at an airport may influence resulting lead concentrations in
soil (i.e., multiple runways may provide for more wide-spread dispersal
of the lead over a larger area than that potentially affected at a
single-runway airport).
---------------------------------------------------------------------------
\148\ Heiken et al., 2014. ACRP Web-Only Document 21:
Quantifying Aircraft Lead Emissions at Airports. Contractor's Final
Report for ACRP 02-34. Available at https://www.trb.org/Publications/Blurbs/172599.aspx.
\149\ McCumber and Strevett 2017. A Geospatial Analysis of Soil
Lead Concentrations Around Regional Oklahoma Airports. Chemosphere
167:62-70.
\150\ Kavouras et al., 2013. Bioavailable Lead in Topsoil
Collected from General Aviation Airports. The Collegiate Aviation
Review International 31(1):57-68. Available at https://doi.org/10.22488/okstate.18.100438.
\151\ Heiken et al., 2014. ACRP Web-Only Document 21:
Quantifying Aircraft Lead Emissions at Airports. Contractor's Final
Report for ACRP 02-34. Available at https://www.trb.org/Publications/Blurbs/172599.aspx.
\152\ EPA (2010) Development and Evaluation of an Air Quality
Modeling Approach for Lead Emissions from Piston-Engine Aircraft
Operating on Leaded Aviation Gasoline. EPA, Washington, DC, EPA-420-
R-10-007, 2010. https://nepis.epa.gov/Exe/ZyPDF.cgi/P1007H4Q.PDF?Dockey=P1007H4Q.PDF.
\153\ Environment Canada (2000) Airborne Particulate Matter,
Lead and Manganese at Buttonville Airport. Toronto, Ontario, Canada:
Conor Pacific Environmental Technologies for Environmental
Protection Service, Ontario Region.
\154\ Lejano and Ericson 2005. Tragedy of the Temporal Commons:
Soil-Bound Lead and the Anachronicity of Risk. Journal of
Environmental Planning and Management. 48(2):301-320.
---------------------------------------------------------------------------
c. Potential for Lead Emissions From Piston-Engine Aircraft To Impact
Agricultural Products
Studies conducted near stationary sources of lead emissions (e.g.,
smelters) have shown that atmospheric lead sources can lead to
contamination of agricultural products, such as
vegetables.155 156 In this way, air lead sources may
contribute to dietary exposure pathways.\157\ As described in Section
II.A.1 of this document, piston-engine aircraft are used in the
application of pesticides, fertilizers and seeding crops for human and
animal consumption and as such, provide a potential route of exposure
for lead in food. To minimize drift of pesticides and other
applications from the intended target, pilots are advised to maintain a
height between eight and 12 feet above the target crop during
application.\158\ The low flying height is needed to minimize the drift
of the fertilizer and pesticide particles away from their intended
target. An unintended consequence of this practice is that exhaust
emissions of lead have a substantially increased potential for directly
depositing on vegetation and surrounding soil. Lead halides, the
primary form of lead emitted by engines operating on leaded fuel,\159\
are slightly water soluble and, therefore, may be more readily absorbed
by plants than other forms of inorganic lead.
---------------------------------------------------------------------------
\155\ EPA (2013) ISA for Lead. Section 3.1.3.3. ``Dietary Pb
Exposure.'' p. 3-20 through 3-24. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
\156\ EPA (2006) AQC for Lead. Section 8.2.2. EPA, Washington,
DC, EPA/600/R-5/144aF, 2006.
\157\ EPA (2006) AQC for Lead. Section 8.2.2. EPA, Washington,
DC, EPA/600/R-5/144aF, 2006.
\158\ O'Connor-Marer. Aerial Applicator's Manual: A National
Pesticide Applicator Certification Study Guide. p. 40. National
Association of State Departments of Agriculture Research Foundation.
Available at https://www.agaviation.org/Files/RelatedEntities/Aerial_Applicators_Manual.pdf.
\159\ The additive used in the fuel to scavenge lead determines
the chemical form of the lead halide emitted; because ethylene
dibromide is added to leaded aviation gasoline used in piston-engine
aircraft, the lead halide emitted is in the form of lead dibromide.
---------------------------------------------------------------------------
The 2006 AQCD indicated that surface deposition of lead onto plants
may be significant.\160\ Atmospheric deposition of lead provides a
pathway for lead in vegetation as a result of contact with above-ground
portions of the plant.161 162 163 Livestock may subsequently
be exposed to lead in vegetation (e.g., grasses and silage) and in
surface soils via incidental ingestion of soil while grazing.\164\
---------------------------------------------------------------------------
\160\ EPA (2006) AQC for Lead. pp. 7-9 and AXZ7-39. EPA,
Washington, DC, EPA/600/R-5/144aF, 2006.
\161\ EPA (2006) AQC for Lead. p. AXZ7-39. EPA, Washington, DC,
EPA/600/R-5/144aF, 2006.
\162\ EPA (1986) AQC for Lead. Sections 6.5.3. EPA, Washington,
DC, EPA-600/8-83/028aF-dF (NTIS PB87142386), 1986.
\163\ EPA (1986) AQC for Lead. Section 7.2.2.2.1.EPA,
Washington, DC, EPA-600/8-83/028aF-dF (NTIS PB87142386), 1986.
\164\ EPA (1986) AQC for Lead. Section 7.2.2.2.2. EPA,
Washington, DC, EPA-600/8-83/028aF-dF (NTIS PB87142386), 1986.
---------------------------------------------------------------------------
d. Potential for Lead Emissions From Piston-Engine Aircraft To Impact
Aquatic Ecosystems
As discussed in Section 6.4 of the 2013 Lead ISA, lead
bioaccumulates in the tissues of aquatic organisms through ingestion of
food and water or direct uptake from the environment (e.g., across
membranes such as gills or skin).\165\ Alkyl lead, in particular, has
been identified by the EPA as a Persistent, Bioaccumulative, and Toxic
(PBT) pollutant.\166\ There are 527 seaport facilities in the U.S., and
landing and take-off activity by seaplanes at these facilities provides
a direct pathway for emission of organic and inorganic lead to the air
near/above inland waters and ocean seaports where these aircraft
operate.\167\ Inland airports may also provide a direct pathway for
emission of organic and inorganic lead to the air near/above inland
waters. Lead emissions from piston-engine aircraft operating at
seaplane facilities as well as airports and heliports near water bodies
can enter the aquatic ecosystem by either deposition from ambient air
or runoff of lead deposited to surface soils.
---------------------------------------------------------------------------
\165\ EPA (2013) ISA for Lead. Section 6.4.2. ``Biogeochemistry
and Chemical Effects of Pb in Freshwater and Saltwater Systems.'' p.
6-147. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\166\ EPA (2002) Persistent, Bioaccumulative, and Toxic
Pollutants (PBT) Program. PBT National Action Plan for Alkyl-Pb.
Washington, DC. June. 2002.
\167\ See FAA's NASR. Available at https://www.faa.gov/air_traffic/flight_info/aeronav/aero_data/eNASR_Browser/.
---------------------------------------------------------------------------
In addition to deposition of lead from engine emissions by piston-
powered aircraft, lead may enter aquatic systems from the pre-flight
inspection of the fuel for contaminants that pilots conduct. While some
pilots return the checked fuel to their fuel tank or dispose of it in a
receptacle provided on the airfield, some pilots discard the fuel onto
the tarmac, ground, or water, in the case of a fuel check being
conducted on a seaplane. Lead in the fuel discarded to the environment
may evaporate to the air and may be taken up by the surface on which it
is discarded. Lead on tarmac or soil surfaces is available for runoff
to surface water. Tetraethyl lead in the avgas directly discarded to
water will be available for uptake and bioaccumulation in aquatic life.
The National Academy of Sciences Airport Cooperative Research Program
(ACRP) conducted a survey study of pilots' fuel sampling and disposal
practices. Among the 146 pilots responding to the survey, 36 percent
indicated they discarded all fuel check samples to the ground
regardless of contamination status and 19 percent of the pilots
indicated they discarded only contaminated fuel to the ground.\168\
Leaded avgas discharged to the ground and water includes other
[[Page 62767]]
hazardous fuel components such as ethylene dibromide.\169\
---------------------------------------------------------------------------
\168\ National Academies of Sciences, Engineering, and Medicine
2014. Best Practices for General Aviation Aircraft Fuel-Tank
Sampling. Washington, DC: The National Academies Press. https://doi.org/10.17226/22343.
\169\ Memorandum to Docket EPA-HQ-OAR-2022-0389. Potential
Exposure to Non-exhaust Lead and Ethylene Dibromide. June 15, 2022.
Docket ID EPA-HQ-2022-0389.
---------------------------------------------------------------------------
5. Consideration of Environmental Justice and Children in Populations
Residing Near Airports
This section provides a description of how many people live in
close proximity to airports where they may be exposed to airborne lead
from aircraft engine emissions of lead (referred to here as the ``near-
airport'' population). This section also provides the demographic
composition of the near-airport population, with attention to
implications related to environmental justice (EJ) and the population
of children in this near-source environment. Consideration of EJ
implications in the population living near airports is important
because blood lead levels in children from low-income households remain
higher than those in children from higher income households, and the
most exposed Black children still have higher blood lead levels than
the most exposed non-Hispanic White children.\170\ \171\ \172\
---------------------------------------------------------------------------
\170\ EPA (2013) ISA for Lead. Section 5.4. ``Summary.'' p. 5-
40. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\171\ EPA. America's Children and the Environment. Summary of
blood lead levels in children updated in 2022, available at https://www.epa.gov/americaschildrenenvironment/biomonitoring-lead. Data
source: Centers for Disease Control and Prevention, National Report
on Human Exposure to Environmental Chemicals. Blood Lead (2011-
2018). Updated March 2022. Available at https://www.cdc.gov/exposurereport/report/pdf/cgroup2_LBXBPB_2011-p.pdf.
\172\ The relative contribution of lead emissions from covered
aircraft engines to these disparities has not been determined and is
not a goal of the evaluation described here.
---------------------------------------------------------------------------
Executive Orders 12898 (59 FR 7629, February 16, 1994) and 14008
(86 FR 7619, February 1, 2021) direct Federal agencies, to the greatest
extent practicable and permitted by law, to make achieving EJ part of
their mission by identifying and addressing, as appropriate,
disproportionately high and adverse human health or environmental
effects of their programs, policies, and activities on people of color
populations and low-income populations in the United States. The EPA
defines environmental justice as the fair treatment and meaningful
involvement of all people regardless of race, color, national origin,
or income with respect to the development, implementation, and
enforcement of environmental laws, regulations, and policies.
For the reasons described in Supplementary Information Section D,
our consideration of EJ implications here is focused on describing
conditions relevant to the most recent year for which demographic data
are available. The analysis described here provides information
regarding whether some demographic groups are more highly represented
in the near-airport environment compared with people who live farther
from airports. Residential proximity to airports implies that there is
an increased potential for exposure to lead from covered aircraft
engine emissions.\173\ As described in Section II.A.3 of this document,
several studies have measured higher concentrations of lead in air near
airports with piston-engine aircraft activity. Additionally, as noted
in Section II.A of this document, two studies have reported increased
blood lead levels in children with increasing proximity to
airports.\174\ \175\
---------------------------------------------------------------------------
\173\ Residential proximity to a source of a specific air
pollutant(s) is a widely used surrogate measure to evaluate the
potential for higher exposures to that pollutant (EPA Technical
Guidance for Assessing Environmental Justice in Regulatory Analysis.
Section 4.2.1). Data presented in Section II.A.3 demonstrate that
lead concentrations in air near the runup area can exceed the lead
NAAQS and concentrations decrease sharply with distance from the
ground-based aircraft exhaust and vary with the amount of aircraft
activity at an airport. Not all people living within 500 meters of a
runway are expected to be equally exposed to lead.
\174\ Miranda et al., 2011. A Geospatial Analysis of the Effects
of Aviation Gasoline on Childhood Blood Lead Levels. Environmental
Health Perspectives. 119:1513-1516.
\175\ Zahran et al., 2017. The Effect of Leaded Aviation
Gasoline on Blood Lead in Children. Journal of the Association of
Environmental and Resource Economists. 4(2):575-610.
---------------------------------------------------------------------------
We first summarize here the literature on disparity with regard to
those who live in proximity to airports. Then we describe the analyses
the EPA has conducted to evaluate potential disparity in the population
groups living near runways where piston-engine aircraft operate
compared to those living elsewhere.
Numerous studies have found that environmental hazards such as air
pollution are more prevalent in areas where people of color and low-
income populations represent a higher fraction of the population
compared with the general population, including near transportation
sources.\176\ \177\ \178\ \179\ \180\ The literature includes studies
that have reported on communities in close proximity to airports that
are disproportionately represented by people of color and low-income
populations. McNair (2020) described nineteen major airports that
underwent capacity expansion projects between 2000 and 2010, thirteen
of which had a large concentration or presence of persons of color,
foreign-born persons or low-income populations nearby.\181\ Woodburn
(2017) reported on changes in communities near airports from 1970-2010,
finding suggestive evidence that at many hub airports over time, the
presence of marginalized groups residing in close proximity to airports
increased.\182\ Rissman et al. (2013) reported that with increasing
proximity to the Hartsfield-Jackson Atlanta International Airport,
exposures to particulate matter were higher, and there were lower home
values, income, education, and percentage of white residents.\183\
---------------------------------------------------------------------------
\176\ Rowangould 2013. A census of the near-roadway population:
public health and environmental justice considerations.
Transportation Research Part D 25:59-67. https://dx.doi.org/10.1016/j.trd.2013.08.003.
\177\ Marshall et al., 2014. Prioritizing environmental justice
and equality: diesel emissions in Southern California. Environmental
Science & Technology 48: 4063-4068. https://doi.org/10.1021/es405167f.
\178\ Marshall 2008. Environmental inequality: air pollution
exposures in California's South Coast Air Basin. Atmospheric
Environment 21:5499-5503. https://doi.org/10.1016/j.atmosenv.2008.02.005.
\179\ Tessum et al., 2021. PM2.5 polluters
disproportionately and systemically affect people of color in the
United States. Science Advances 7:eabf4491.
\180\ Mohai et al., 2009. Environmental justice. Annual Reviews
34:405-430. Available at https://doi.org/10.1146/annurev-environ-082508-094348.
\181\ McNair 2020. Investigation of environmental justice
analysis in airport planning practice from 2000 to 2010.
Transportation Research Part D 81:102286.
\182\ Woodburn 2017. Investigating neighborhood change in
airport-adjacent communities in multiairport regions from 1970 to
2010. Journal of the Transportation Research Board, 2626, 1-8.
\183\ Rissman et al., 2013. Equity and health impacts of
aircraft emissions at the Hartfield-Jackson Atlanta International
Airport. Landscape and Urban Planning, 120: 234-247.
---------------------------------------------------------------------------
The EPA used two approaches to understand whether some members of
the population (e.g., children five and under, people of color,
indigenous populations, low-income populations) represent a larger
share of the people living in proximity to airports where piston-engine
aircraft operate compared with people who live farther away from these
airports. In the first approach, we evaluated people living within, and
children attending school within, 500 meters of all of the
approximately 20,000 airports in the U.S., using methods described in
the EPA's report titled ``National Analysis of the Populations Residing
Near or Attending
[[Page 62768]]
School Near U.S. Airports.'' \184\ In the second approach, we evaluated
people living near the NPIAS airports in the conterminous 48 states. As
noted in Section II.A.1 of this document, the NPIAS airports support
the majority of piston-engine aircraft activity that occurs in the U.S.
Among the NPIAS airports, we compared the demographic composition of
people living within one kilometer of runways with the demographic
composition of people living at a distance of one to five kilometers
from the same airports.
---------------------------------------------------------------------------
\184\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. EPA, Washington, DC, EPA-420-R-20-
003, 2020. EPA responses to peer review comments on the report are
available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YISM.pdf.
---------------------------------------------------------------------------
The distances analyzed for those people living closest to airports
(i.e., distances of 500 meters and 1,000 meters) were chosen for
evaluation following from the air quality monitoring and modeling data
presented in Section II.A.3 of this document. Specifically, the EPA's
modeling and monitoring data indicate that concentrations of lead from
piston-engine aircraft emissions can be elevated above background
levels at distances of 500 meters over a rolling three-month period. On
individual days, concentrations of lead from piston-engine aircraft
emissions can be elevated above background levels at distances of 1,000
meters on individual days downwind of a runway, depending on aircraft
activity and prevailing wind direction.185 186 187
---------------------------------------------------------------------------
\185\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. EPA, Washington, DC, EPA-420-R-20-
003, 2020.
\186\ Carr et. al., 2011. Development and evaluation of an air
quality modeling approach to assess near-field impacts of lead
emissions from piston-engine aircraft operating on leaded aviation
gasoline. Atmospheric Environment, 45 (32), 5795-5804. DOI: https://dx.doi.org/10.1016/j.atmosenv.2011.07.017.
\187\ We do not assume or expect that all people living within
500m or 1,000m of a runway are exposed to lead from piston-engine
aircraft emissions, and the wide range of activity of piston-engine
aircraft at airports nationwide suggests that exposure to lead from
aircraft emissions is likely to vary widely.
---------------------------------------------------------------------------
Because the U.S. has a dense network of airports, many of which
have neighboring communities, we first quantified the number of people
living and children attending school within 500 meters of the
approximately 20,000 airports in the U.S. The results of this analysis
are summarized at the national scale in the EPA's report titled
``National Analysis of the Populations Residing Near or Attending
School Near U.S. Airports.'' \188\ From this analysis, the EPA
estimates that approximately 5.2 million people live within 500 meters
of an airport runway, 363,000 of whom are children age five and under.
The EPA also estimates that 573 schools attended by 163,000 children in
kindergarten through twelfth grade are within 500 meters of an airport
runway.\189\
---------------------------------------------------------------------------
\188\ In this analysis, we included populations living in census
blocks that intersected the 500-meter buffer around each runway in
the U.S. Potential uncertainties in this approach are described in
our report National Analysis of the Populations Residing Near or
Attending School Near U.S. Airports. EPA-420-R-20-001, available at
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG4A.pdf, and in the
EPA responses to peer review comments on the report, available here:
https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YISM.pdf.
\189\ EPA (2020) National Analysis of the Populations Residing
Near or Attending School Near U.S. Airports. EPA-420-R-20-001.
Available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG4A.pdf.
---------------------------------------------------------------------------
In order to identify potential disparities in the near-airport
population, we first evaluated populations at the state level. Using
the U.S. Census population data for each State in the U.S., we compared
the percent of people by age, race and indigenous peoples (i.e.,
children five and under, Black, Asian, and Native American or Alaska
Native) living within 500 meters of an airport runway with the percent
by age, race, and indigenous peoples comprising the state
population.\190\ Using the methodology described in Clarke (2022), the
EPA identified states in which children, Black, Asian, and Native
American or Alaska Native populations represent a greater fraction of
the population compared with the percent of these groups in the state
population.\191\ Results of this analysis are presented in the
following tables.\192\ This state-level analysis presents summary
information for a subset of potentially relevant demographic
characteristics. We present data in this section regarding a wider
array of demographic characteristics when evaluating populations living
near NPIAS airports.
---------------------------------------------------------------------------
\190\ Clarke. Memorandum to Docket EPA-HQ-OAR-2022-0389.
Estimation of Population Size and Demographic Characteristics among
People Living Near Airports by State in the United States. May 31,
2022. Docket ID EPA-HQ-2022-0389.
\191\ Clarke. Memorandum to Docket EPA-HQ-OAR-2022-0389.
Estimation of Population Size and Demographic Characteristics among
People Living Near Airports by State in the United States. May 31,
2022. Docket ID EPA-HQ-2022-0389.
\192\ These data are presented in tabular form for all states in
this memorandum located in the docket: Clarke. Memorandum to Docket
EPA-HQ-OAR-2022-0389. Estimation of Population Size and Demographic
Characteristics among People Living Near Airports by State in the
United States. May 31, 2022. Docket ID EPA-HQ-2022-0389.
---------------------------------------------------------------------------
Among children five and under, there were three states (Nevada,
South Carolina, and South Dakota), in which the percent of children
five and under living within 500 meters of a runway represent a greater
fraction of the population by a difference of one percent or greater
compared with the percent of children five and under in the state
population (Table 3).
Table 3--The Population of Children Five Years and Under Within 500 Meters of an Airport Runway Compared to the
State Population of Children Five Years and Under
----------------------------------------------------------------------------------------------------------------
Percent of Percent of Number of Number of
children aged children aged children aged children aged
State five years and five years and five years and five years and
under within under within under within under in the
500 meters the state 500 meters state
----------------------------------------------------------------------------------------------------------------
Nevada.......................................... 10 8 1,000 224,200
South Carolina.................................. 9 8 400 361,400
South Dakota.................................... 11 9 3,000 71,300
----------------------------------------------------------------------------------------------------------------
There were nine states in which the Black population represented a
greater fraction of the population living in the near-airport
environment by a difference of one percent or greater compared with the
state as a whole. These states were California, Kansas, Kentucky,
Louisiana, Mississippi, Nevada, South Carolina, West Virginia, and
Wisconsin (Table 4).
[[Page 62769]]
Table 4--The Black Population Within 500 Meters of an Airport Runway and the Black Population, by State
----------------------------------------------------------------------------------------------------------------
Black
Percent Black Percent Black population Black
State within 500 within the within 500 population in
meters state meters the state
----------------------------------------------------------------------------------------------------------------
California...................................... 8 7 18,981 2,486,500
Kansas.......................................... 8 6 1,240 173,300
Kentucky........................................ 9 8 3,152 342,800
Louisiana....................................... 46 32 14,669 1,463,000
Mississippi..................................... 46 37 8,542 1,103,100
Nevada.......................................... 12 9 1,794 231,200
South Carolina.................................. 31 28 10,066 1,302,900
West Virginia................................... 10 3 1,452 63,900
Wisconsin....................................... 9 6 4,869 367,000
----------------------------------------------------------------------------------------------------------------
There were three states with a greater fraction of Asians in the
near-airport environment compared with the state as a whole by a
difference of one percent or greater: Indiana, Maine, and New Hampshire
(Table 5).
Table 5--The Asian Population Within 500 Meters of an Airport Runway and the Asian Population, by State
----------------------------------------------------------------------------------------------------------------
Asian
Percent Asian Percent Asian population Asian
State within 500 within the within 500 population in
meters state meters the state
----------------------------------------------------------------------------------------------------------------
Indiana......................................... 4 2 1,681 105,500
Maine........................................... 2 1 406 13,800
New Hampshire................................... 4 2 339 29,000
----------------------------------------------------------------------------------------------------------------
Among Native Americans and Alaska Natives, there were five states
(Alaska, Arizona, Delaware, South Dakota, and New Mexico) where the
near-airport population had greater representation by Native Americans
and Alaska Natives compared with the portion of the population they
comprise at the state level by a difference of one percent or greater.
In Alaska, as anticipated due to the critical nature of air travel for
the transportation infrastructure in that state, the disparity in
residential proximity to a runway was the largest; 16,000 Alaska
Natives were estimated to live within 500 meters of a runway,
representing 48 percent of the population within 500 meters of an
airport runway compared with 15 percent of the Alaska state population
(Table 6).
Table 6--The Native American and Alaska Native Population Within 500 Meters of an Airport Runway and the Native
American and Alaska Native Population, by State
----------------------------------------------------------------------------------------------------------------
Native
Percent Native Percent Native American and Native
American and American and Alaska Native American and
State Alaska Native Alaska Native population Alaska Native
within 500 within the within 500 population in
meters state meters the state
----------------------------------------------------------------------------------------------------------------
Alaska.......................................... 48 15 16,020 106,300
Arizona......................................... 18 5 5,017 335,300
Delaware........................................ 2 1 112 5,900
New Mexico...................................... 21 10 2,265 208,900
South Dakota.................................... 22 9 1,606 72,800
----------------------------------------------------------------------------------------------------------------
In a separate analysis, the EPA focused on evaluating the potential
for disparities in populations residing near the NPIAS airports. The
EPA compared the demographic composition of people living within one
kilometer of runways at 2,022 of the approximately 3,300 NPIAS airports
with the demographic composition of people living at a distance of one
to five kilometers from the same airports.\193\ \194\ In this analysis,
over one-fourth of airports (i.e., 515) were identified at which
children under five were more highly represented in the zero to one
kilometer distance compared with the percent of children under five
living one to five kilometers away (Table 7). There were 666 airports
where people of color had a greater presence in the zero to one
kilometer area closest
[[Page 62770]]
to airport runways than in populations farther away. There were 761
airports where people living at less than two-times the Federal Poverty
Level represented a higher proportion of the overall population within
one kilometer of airport runways compared with the proportion of people
living at less than two-times the Federal Poverty Level among people
living one to five kilometers away.
---------------------------------------------------------------------------
\193\ For this analysis, we evaluated the 2,022 airports with a
population of greater than 100 people inside the zero to one
kilometer distance to avoid low population counts distorting the
assessment of percent contributions of each group to the total
population within the zero to one kilometer distance.
\194\ Kamal et.al., Memorandum to Docket EPA-HQ-OAR-2022-0389.
Analysis of Potential Disparity in Residential Proximity to Airports
in the Conterminous United States. May 24, 2022. Docket ID EPA-HQ-
2022-0389. Methods used are described in this memo and include the
use of block group resolution data to evaluate the representation of
different demographic groups near-airport and for those living one
to five kilometers away.
Table 7--Number of Airports (Among the 2,022 Airports Evaluated) With Disparity for Certain Demographic
Populations Within One Kilometer of an Airport Runway in Relation to the Comparison Population Between One and
Five Kilometers From an Airport Runway
----------------------------------------------------------------------------------------------------------------
Number of airports with disparity \a\
-------------------------------------------------------------------------------
Demographic group Total airports Disparity 5- Disparity 10-
with disparity Disparity 1-5% 10% 20% Disparity 20%+
----------------------------------------------------------------------------------------------------------------
Children under five years of age 515 507 7 1 0
People with income less than 761 307 223 180 51
twice the Federal Poverty Level
People of Color (all races, 666 377 126 123 40
ethnicities and indigenous
peoples).......................
Non-Hispanic Black.............. 405 240 77 67 21
Hispanic........................ 551 402 85 47 17
Non-Hispanic Asian.............. 268 243 18 4 3
Non-Hispanic Native American or 144 130 6 7 1
Alaska Native \195\............
Non-Hispanic Hawaiian or Pacific 18 17 1 0 0
Islander.......................
Non-Hispanic Other Race......... 11 11 0 0 0
Non-Hispanic Two or More Races.. 226 226 0 0 0
----------------------------------------------------------------------------------------------------------------
To understand the extent of the potential disparity among the 2,022
NPIAS airports, Table 7 provides information about the distribution in
the percent differences in the proportion of children, individuals with
incomes below two-times the Federal Poverty Level, and people of color
living within one kilometer of a runway compared with those living one
to five kilometers away. For children, Table 7 indicates that for the
vast majority of these airports where there is a higher percentage of
children represented in the near-airport population, differences are
relatively small (e.g., less than five percent). For the airports where
disparity is evident on the basis of poverty, race and ethnicity, the
disparities are potentially large, ranging up to 42 percent for those
with incomes below two-times the Federal Poverty Level, and up to 45
percent for people of color.\196\
---------------------------------------------------------------------------
\195\ This analysis of 2,022 NPIAS airports did not include
airports in Alaska.
\196\ Kamal et.al., Memorandum to Docket EPA-HQ-OAR-2022-0389.
Analysis of Potential Disparity in Residential Proximity to Airports
in the Conterminous United States. May 24, 2022. Docket ID EPA-HQ-
2022-0389.
---------------------------------------------------------------------------
There are uncertainties in the results provided here inherent to
the proximity-based approach used. These uncertainties include the use
of block group data to provide population numbers for each demographic
group analyzed, and uncertainties in the Census data, including from
the use of data from different analysis years (e.g., 2010 Census Data
and 2018 income data). These uncertainties are described, and their
implications discussed in Kamal et.al. (2022).\197\
---------------------------------------------------------------------------
\197\ Kamal et.al., Memorandum to Docket EPA-HQ-OAR-2022-0389.
Analysis of Potential Disparity in Residential Proximity to Airports
in the Conterminous United States. May 24, 2022. Docket ID EPA-HQ-
2022-0389.
---------------------------------------------------------------------------
The data summarized here indicate that there is a greater
prevalence of children under five years of age, an at-risk population
for lead effects, within 500 meters or one kilometer of some airports
compared to more distant locations. This information also indicates
that there is a greater prevalence of people of color and of low-income
populations within 500 meters or one kilometer of some airports
compared with people living more distant. If such differences were to
contribute to disproportionate and adverse impacts on people of color
and low-income populations, they could indicate a potential EJ concern.
Given the number of children in close proximity to runways, including
those in EJ populations, there is a potential for substantial
implications for children's health. The EPA invites comment on the
potential EJ impacts of aircraft lead emissions from aircraft engines
and on the potential impacts on children in close proximity to runways
where piston-engine aircraft operate.
B. Federal Actions To Reduce Lead Exposure
The federal government has a longstanding commitment to programs to
reduce exposure to lead, particularly for children. In December 2018,
the President's Task Force on Environmental Health Risks and Safety
Risks to Children released the Federal Lead Action Plan, detailing the
federal government's commitments and actions to reduce lead exposure in
children, some of which are described in this section.\198\ In this
section, we describe some of the EPA's actions to reduce lead exposures
from air, water, lead-based paint, and contaminated sites.
---------------------------------------------------------------------------
\198\ Federal Lead Action Plan to Reduce Childhood Lead
Exposures and Associated Health Impacts. (2018) President's Task
Force on Environmental Health Risks and Safety Risks to Children.
Available at https://www.epa.gov/sites/default/files/2018-12/documents/fedactionplan_lead_final.pdf.
---------------------------------------------------------------------------
In 1976, the EPA listed lead under CAA section 108, making it what
is called a ``criteria air pollutant.'' \199\ Once lead was listed, the
EPA issued primary and secondary NAAQS under sections 109(b)(1) and
(2), respectively. The EPA issued the first NAAQS for lead in 1978 and
revised the lead NAAQS in 2008 by reducing the level of the standard
from 1.5 micrograms per cubic meter to 0.15 micrograms per cubic meter,
and revising the averaging time and form to an average over a
consecutive three-month period, as described in 40 CFR 50.16.\200\ The
EPA's 2016 Federal Register notice describes the Agency's decision to
retain the existing Lead
[[Page 62771]]
NAAQS.\201\ The Lead NAAQS is currently undergoing review.\202\
---------------------------------------------------------------------------
\199\ 41 FR 14921 (April 8, 1976). See also, e.g., 81 FR at
71910 (Oct. 18, 2016) for a description of the history of the
listing decision for lead under CAA section 108.
\200\ 73 FR 66965 (Nov. 12, 2008).
\201\ 81 FR 71912-71913 (Oct. 18, 2016).
\202\ Documents pertaining to the current review of the NAAQS
for Lead can be found here: https://www.epa.gov/naaqs/lead-pb-air-quality-standards.
---------------------------------------------------------------------------
States are primarily responsible for ensuring attainment and
maintenance of the NAAQS. Under section 110 of the Act and related
provisions, states are to submit, for EPA review and, if appropriate,
approval, state implementation plans that provide for the attainment
and maintenance of such standards through control programs directed to
sources of the pollutants involved. The states, in conjunction with the
EPA, also administer the Prevention of Significant Deterioration
program for these pollutants.
Additional EPA programs to address lead in the environment include
the Federal Motor Vehicle Control program under Title II of the Act,
which involves controls for motor vehicles and nonroad engines and
equipment; the new source performance standards under section 111 of
the Act; and emissions standards for solid waste incineration units and
the national emission standards for hazardous air pollutants (NESHAP)
under sections 129 and 112 of the Act, respectively.
The EPA has taken a number of actions associated with these air
pollution control programs, including completion of several regulations
requiring reductions in lead emissions from stationary sources
regulated under the CAA sections 112 and 129. For example, in January
2012, the EPA updated the NESHAP for the secondary lead smelting source
category.\203\ These amendments to the original maximum achievable
control technology standards apply to facilities nationwide that use
furnaces to recover lead from lead-bearing scrap, mainly from
automobile batteries. Regulations completed in 2013 for commercial and
industrial solid waste incineration units also require reductions in
lead emissions.\204\
---------------------------------------------------------------------------
\203\ 77 FR 555 (Jan. 5, 2012).
\204\ 78 FR 9112 (Feb. 7, 2013).
---------------------------------------------------------------------------
A broad range of Federal programs beyond those that focus on air
pollution control provide for nationwide reductions in environmental
releases and human exposures to lead. For example, pursuant to section
1417 of the Safe Drinking Water Act (SDWA), any pipe, pipe or plumbing
fitting or fixture, solder, or flux for potable water applications may
not be used in new installations or repairs or introduced into commerce
unless it is considered ``lead free'' as defined by that Act.\205\ Also
under section 1412 of the SDWA, the EPA's 1991 Lead and Copper Rule
\206\ regulates lead in public drinking water systems through corrosion
control and other utility actions which work together to minimize lead
levels at the tap.\207\ On January 15, 2021, the agency published the
Lead and Copper Rule Revisions (LCRR) \208\ and subsequently reviewed
the rule in accordance with Executive Order 13990.\209\ While the LCRR
took effect in December 2021, the agency concluded that there are
significant opportunities to improve the LCRR.\210\ The EPA is
developing a new proposed rule, the Lead and Copper Rule Improvements
(LCRI),\211\ that would further strengthen the lead drinking water
regulations. The EPA identified priority improvements for the LCRI:
proactive and equitable lead service line replacement (LSLR),
strengthening compliance tap sampling to better identify communities
most at risk of lead in drinking water and to compel lead reduction
actions, and reducing the complexity of the regulation through
improvement of ``methods to identify and trigger action in communities
that are most at risk of elevated drinking water levels.'' \212\ The
EPA intends to propose the LCRI and take final action on it prior to
October 16, 2024.
---------------------------------------------------------------------------
\205\ Effective in Jan. 2014, the amount of lead permitted in
pipes, fittings, and fixtures was lowered. See, Section 1417 of the
Safe Drinking Water Act: Prohibition on Use of Lead Pipes, Solder,
and Flux at https://www.epa.gov/sdwa/use-lead-free-pipes-fittings-fixtures-solder-and-flux-drinking-water.
\206\ 40 CFR 141 Subpart I (June 7, 1991).
\207\ 40 CFR 141 Subpart I (June 7, 1991).
\208\ 86 FR 4198. (Jan. 15, 2021).
\209\ E.O. 13990. Protecting Public Health and the Environment
and Restoring Science to Tackle the Climate Crisis. 86 FR 7037 (Jan.
20, 2021).
\210\ 86 FR 31939. (Dec. 17, 2021).
\211\ See https://www.epa.gov/ground-water-and-drinking-water/review-national-primary-drinking-water-regulation-lead-and-copper.
Accessed on Nov. 30, 2021.
\212\ 86 FR 31939 (Dec. 17, 2021).
---------------------------------------------------------------------------
Federal programs to reduce exposure to lead in paint, dust, and
soil are specified under the comprehensive federal regulatory framework
developed under the Residential Lead-Based Paint Hazard Reduction Act
(Title X). Under Title X (codified, in part, as Title IV of the Toxic
Substances Control Act [TSCA]), the EPA has established regulations and
associated programs in six categories: (1) Training, certification and
work practice requirements for persons engaged in lead-based paint
activities (abatement, inspection and risk assessment); accreditation
of training providers; and authorization of state and Tribal lead-based
paint programs; (2) training, certification, and work practice
requirements for persons engaged in home renovation, repair and
painting (RRP) activities; accreditation of RRP training providers; and
authorization of state and Tribal RRP programs; (3) ensuring that, for
most housing constructed before 1978, information about lead-based
paint and lead-based paint hazards flows from sellers to purchasers,
from landlords to tenants, and from renovators to owners and occupants;
(4) establishing standards for identifying dangerous levels of lead in
paint, dust and soil; (5) providing grant funding to establish and
maintain state and Tribal lead-based paint programs; and (6) providing
information on lead hazards to the public, including steps that people
can take to protect themselves and their families from lead-based paint
hazards.
The most recent rules issued under Title IV of TSCA revised the
dust-lead hazard standards (DLHS) and dust-lead clearance levels (DLCL)
which were established in a 2001 final rule entitled ``Identification
of Dangerous Levels of Lead.'' \213\ The DLHS are incorporated into the
requirements and risk assessment work practice standards in the EPA's
Lead-Based Paint Activities Rule, codified at 40 CFR part 745, subpart
L. They provide the basis for risk assessors to determine whether dust-
lead hazards are present in target housing (i.e., most pre-1978
housing) and child-occupied facilities (pre-1978 nonresidential
properties where children 6 years of age or under spend a significant
amount of time such as daycare centers and kindergartens). If dust-lead
hazards are present, the risk assessor will identify acceptable options
for controlling the hazards in the respective property, which may
include abatements and/or interim controls. In July 2019, the EPA
published a final rule revising the DLHS from 40 micrograms per square
foot and 250 micrograms per square foot to 10 micrograms per square
foot and 100 micrograms per square foot of lead in dust on floors and
windowsills, respectively.\214\ The DLCL are used to evaluate the
effectiveness of a cleaning following an abatement. If the dust-lead
levels are not below the clearance levels, the components (i.e.,
floors, windowsills, troughs) represented by the failed sample(s) shall
be recleaned and retested. In January 2021, the EPA published a final
rule revising the DLCL to match the DLHS, lowering them from 40
micrograms per square foot and 250 micrograms per square foot to 10
micrograms per square foot and 100 micrograms per square foot on floors
[[Page 62772]]
and windowsills, respectively.\215\ The EPA is now reconsidering the
2019 and 2021 rules in accordance with Executive Order 13990 \216\ and
in response to a May 2021 decision by U.S. Court of Appeals for the
Ninth Circuit.
---------------------------------------------------------------------------
\213\ 66 FR 1206 (Jan. 5, 2001).
\214\ 84 FR 32632 (July 9, 2019).
\215\ 86 FR 983 (Jan. 7, 2021).
\216\ 86 FR 7037 (Jan. 20, 2021).
---------------------------------------------------------------------------
Programs associated with the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA or Superfund) \217\ and
Resource Conservation Recovery Act (RCRA) \218\ also implement removal
and remedial response programs that reduce exposures to the release or
threat of a release of lead and other hazardous substances. The EPA
develops and implements protective levels for lead in soil at Superfund
sites and, together with states, at RCRA corrective action facilities.
The Office of Land and Emergency Management develops policy and
guidance for addressing multimedia lead contamination and determining
appropriate response actions at lead sites. Federal programs, including
those implementing RCRA, provide for management of hazardous substances
in hazardous and municipal solid waste (e.g., 66 FR 58258, November 20,
2001).
---------------------------------------------------------------------------
\217\ For more information about the EPA's CERCLA program, see
www.epa.gov/superfund.
\218\ For more information about the EPA's RCRA program, see
https://www.epa.gov/rcra.
---------------------------------------------------------------------------
C. History of Lead Endangerment Petitions for Rulemaking and the EPA
Responses
The Administrator's proposed findings further respond to several
citizen petitions on this subject including the following: petition for
rulemaking submitted by Friends of the Earth in 2006, petition for
rulemaking submitted by Friends of the Earth, Oregon Aviation Watch and
Physicians for Social Responsibility in 2012, petition for
reconsideration submitted by Friends of the Earth, Oregon Aviation
Watch, and Physicians for Social Responsibility in 2014, and petition
for rulemaking from Alaska Community Action on Toxics, Center for
Environmental Health, Friends of the Earth, Montgomery-Gibbs
Environmental Coalition, Oregon Aviation Watch, the County of Santa
Clara, CA, and the Town of Middleton, WI in 2021. These petitions and
the EPA's responses are described here.\219\
---------------------------------------------------------------------------
\219\ See https://www.epa.gov/regulations-emissions-vehicles-and-engines/petitions-and-epa-response-memorandums-related-lead.
Accessed on Dec. 12, 2021.
---------------------------------------------------------------------------
In a 2003 letter to the EPA, Friends of the Earth initially raised
the issue of the potential for lead emissions from the use of leaded
avgas in general aviation aircraft using piston engines to cause or
contribute to endangerment of public health or welfare.\220\ In 2006,
Friends of the Earth filed a petition with the EPA requesting that the
Administrator find endangerment or, if there was insufficient
information to find endangerment, commence a study of lead emissions
from piston-engine aircraft. In 2007, the EPA issued a Federal Register
notice on the petition requesting comments and information related to a
wide range of issues regarding the use of leaded avgas and potential
public health and welfare exposure issues.\221\ The EPA did not receive
new information to inform the evaluation of whether lead emissions from
aircraft engines using leaded avgas cause or contribute to air
pollution which may reasonably be anticipated to endanger public health
or welfare.
---------------------------------------------------------------------------
\220\ Friends of the Earth (formerly Bluewater Network) comment
dated Dec. 12, 2003, submitted to EPA's 68 FR 56226, published Sept.
30, 2003.
\221\ See 72 FR 64570 (Nov. 16, 2007).
---------------------------------------------------------------------------
In 2010, the EPA further responded to the 2006 petition from
Friends of the Earth by issuing an Advance Notice of Proposed
Rulemaking on Lead Emissions from Piston-Engine Aircraft Using Leaded
Aviation Gasoline (ANPR).\222\ In the ANPR, the EPA described
information currently available and information being collected that
would be used by the Administrator to issue a subsequent proposal
regarding whether, in the Administrator's judgment, aircraft lead
emissions from aircraft using leaded avgas cause or contribute to air
pollution which may reasonably be anticipated to endanger public health
or welfare. After issuing the ANPR, the EPA continued the data
collection and evaluation of information that is described in Sections
II.A, IV and V of this action.
---------------------------------------------------------------------------
\222\ 75 FR 22440-68 (Apr. 28, 2010).
---------------------------------------------------------------------------
In 2012, Friends of the Earth, Physicians for Social
Responsibility, and Oregon Aviation Watch filed a new petition claiming
that, among other things, the EPA had unreasonably delayed in
responding to the 2006 petition from Friends of the Earth because it
had failed to determine whether emissions of lead from general aviation
aircraft engines cause or contribute to air pollution which may
reasonably be anticipated to endanger public health or welfare.\223\
The EPA responded to the 2012 petition with our plan for collecting the
necessary information and conducting a proceeding under CAA section 231
regarding whether lead emissions from piston-engine aircraft cause or
contribute to air pollution that may reasonably be anticipated to
endanger public health or welfare. Friends of the Earth, Physicians for
Social Responsibility, and Oregon Aviation Watch submitted a petition
for reconsideration in 2014 \224\ to which the EPA responded in
2015.\225\
---------------------------------------------------------------------------
\223\ Petitioners filed a complaint in district court seeking to
compel EPA to respond to their 2006 petition for rulemaking and to
issue an endangerment finding and promulgate regulations. The EPA
then issued its response to the petition, mooting that claim of the
complaint. In response to EPA's motion for summary judgment on the
remaining claims, the court concluded that making the endangerment
determination is not a nondiscretionary act or duty and thus that it
lacked jurisdiction to grant the relief requested by plaintiffs.
Friends of the Earth v. EPA, 934 F. Supp. 2d 40, 55 (D.D.C. 2013).
\224\ The petition for reconsideration submitted to EPA by
Friends of the Earth, Physicians for Social Responsibility, and
Oregon Aviation Watch is available at https://www.epa.gov/sites/default/files/2016-09/documents/avgas-petition-reconsider-04-21-14.pdf.
\225\ The 2015 EPA response to the 2014 petition for
reconsideration is available at https://www.epa.gov/sites/default/files/2016-09/documents/ltr-response-av-ld-foe-psr-oaw-2015-1-23.pdf.
---------------------------------------------------------------------------
In 2021, Alaska Community Action on Toxics, Center for
Environmental Health, Friends of the Earth, Montgomery-Gibbs
Environmental Coalition, Oregon Aviation Watch, the County of Santa
Clara, CA, and the Town of Middleton, WI, again petitioned the EPA to
conduct a proceeding under CAA section 231 regarding whether lead
emissions from piston-engine aircraft cause or contribute to air
pollution that may reasonably be anticipated to endanger public health
or welfare.\226\ The EPA responded in 2022 noting our intent to develop
this proposal regarding whether lead emissions from piston-engine
aircraft cause or contribute to air pollution that may reasonably be
anticipated to endanger public health or welfare.\227\
---------------------------------------------------------------------------
\226\ The 2021 petition is available at https://www.epa.gov/system/files/documents/2022-01/aviation-leaded-avgas-petition-exhibits-final-2021-10-12.pdf.
\227\ EPA's response to the 2021 petition is available at
https://www.epa.gov/system/files/documents/2022-01/ltr-response-aircraft-lead-petitions-aug-oct-2022-01-12.pdf.
---------------------------------------------------------------------------
III. Legal Framework for This Action
In this action, the EPA is proposing to make two separate
determinations--an endangerment finding and a cause or contribute
finding--under section 231(a)(2)(A) of the Clean Air Act. The EPA has,
most recently, finalized such findings under CAA section 231 for
greenhouse gases (GHGs) in 2016 (2016 Findings), and in that action the
EPA
[[Page 62773]]
provided a detailed explanation of the legal framework for making such
findings and the statutory interpretations and caselaw supporting its
approach.\228\ In this proposal, the Administrator is using the same
approach of applying a two-part test under section 231(a)(2)(A) as
described in the 2016 Findings and is relying on the same
interpretations supporting that approach, which are briefly described
in this Section, and set forth in greater detail in the 2016
Findings.\229\ This is also the same approach that the EPA used in
making endangerment and cause and contribute findings for GHGs under
section 202(a) of the CAA in 2009 (2009 Findings),\230\ which was
affirmed by the U.S. Court of Appeals for the D.C. Circuit in
2012.\231\ As explained further in the 2016 Findings, the text of the
CAA section concerning aircraft emissions in section 231(a)(2)(A)
mirrors the text of CAA section 202(a) that was the basis for the 2009
Findings.\232\ Accordingly, for the same reasons as discussed in the
2016 Findings, the EPA believes it is reasonable to use the same
approach under section 231(a)(2)(A)'s similar text as was used under
section 202(a) for the 2009 Findings, and it is proposing to act
consistently with that framework for purposes of these proposed section
231 findings.\233\ As this approach has been previously discussed at
length in the 2016 and 2009 Findings, the EPA provides only a brief
description in this proposal.
---------------------------------------------------------------------------
\228\ FR 54422-54475 (Aug. 15, 2016).
\229\ See e.g., 81 FR at 55434-54440 (Aug. 19, 2016).
\230\ 74 FR 66496, 66505-10 (Dec. 15, 2009).
\231\ Coalition for Responsible Regulation, Inc. v. EPA, 684
F.3d 102 (D.C. Cir. 2012) (CRR) (subsequent history omitted).
\232\ 81 FR at 55434 (Aug. 19, 2016).
\233\ 81 FR at 55434 (Aug. 19, 2016).
---------------------------------------------------------------------------
A. Statutory Text and Basis for This Proposal
Section 231(a)(2)(A) of the CAA provides that the ``The
Administrator shall, from time to time, issue proposed emission
standards applicable to the emission of any air pollutant from any
class or classes of aircraft engines which in his judgment causes, or
contributes to, air pollution which may reasonably be anticipated to
endanger public health or welfare.'' \234\ In this proposal, the EPA is
addressing the predicate for regulatory action under CAA section 231
through a two-part test, which as noted previously, is the same as the
test used in the 2016 Findings and in the 2009 Findings.
---------------------------------------------------------------------------
\234\ Regarding ``welfare,'' the CAA states that ``[a]ll
language referring to effects on welfare includes, but is not
limited to, effects on soils, water, crops, vegetation, manmade
materials, animals, wildlife, weather, visibility, and climate,
damage to and deterioration of property, and hazards to
transportation, as well as effects on economic values and on
personal comfort and well-being, whether caused by transformation,
conversion, or combination with other air pollutants.'' CAA section
302(h). Regarding ``public health,'' there is no definition of
``public health'' in the Clean Air Act. The Supreme Court has
discussed the concept of ``public health'' in the context of whether
costs can be considered when setting NAAQS. Whitman v. American
Trucking Ass'n, 531 U.S. 457 (2001). In Whitman, the Court imbued
the term with its most natural meaning: ``the health of the
public.'' Id. at 466.
---------------------------------------------------------------------------
As the first step of the two-part test, the Administrator must
decide whether, in his judgment, the air pollution under consideration
may reasonably be anticipated to endanger public health or welfare. As
the second step, the Administrator must decide whether, in his
judgment, emissions of an air pollutant from certain classes of
aircraft engines cause or contribute to this air pollution. If the
Administrator answers both questions in the affirmative, he will issue
standards under section 231.\235\
---------------------------------------------------------------------------
\235\ See Massachusetts v. EPA, 549 U.S. 497,533 (2007)
(interpreting an analogous provision in CAA section 202).
---------------------------------------------------------------------------
In accordance with the EPA's interpretation of the text of section
231(a)(2)(A), as described in the 2016 Findings, the phrase ``may
reasonably be anticipated'' and the term ``endanger'' in section
231(a)(2)(A) authorize, if not require, the Administrator to act to
prevent harm and to act in conditions of uncertainty.\236\ They do not
limit him to merely reacting to harm or to acting only when certainty
has been achieved; indeed, the references to anticipation and to
endangerment imply that the failure to look to the future or to less
than certain risks would be to abjure the Administrator's statutory
responsibilities. As the D.C. Circuit explained, the language ``may
reasonably be anticipated to endanger public health or welfare'' in CAA
section 202(a) requires a ``precautionary, forward-looking scientific
judgment about the risks of a particular air pollutant, consistent with
the CAA's precautionary and preventive orientation.'' \237\ The court
determined that ``[r]equiring that the EPA find `certain' endangerment
of public health or welfare before regulating greenhouse gases would
effectively prevent the EPA from doing the job that Congress gave it in
[section] 202(a)--utilizing emission standards to prevent reasonably
anticipated endangerment from maturing into concrete harm.'' \238\ The
same language appears in section 231(a)(2)(A), and the same
interpretation applies in that context.
---------------------------------------------------------------------------
\236\ See 81 FR at 54435 (Aug. 19, 2016).
\237\ CRR, 684 F.3d at 122 (internal citations omitted) (June
26, 2012).
\238\ CRR, 684 F.3d at 122 (internal citations omitted) (June
26, 2012).
---------------------------------------------------------------------------
Moreover, by instructing the Administrator to consider whether
emissions of an air pollutant cause or contribute to air pollution in
the second part of the two-part test, the Act makes clear that he need
not find that emissions from any one sector or class of sources are the
sole or even the major part of the air pollution considered. This is
clearly indicated by the use of the term ``contribute.'' Further, the
phrase ``in his judgment'' authorizes the Administrator to weigh risks
and to consider projections of future possibilities, while also
recognizing uncertainties and extrapolating from existing data.
Finally, when exercising his judgment in making both the
endangerment and cause-or-contribute findings, the Administrator
balances the likelihood and severity of effects. Notably, the phrase
``in his judgment'' modifies both ``may reasonably be anticipated'' and
``cause or contribute.''
Often, past endangerment and cause or contribute findings have been
proposed concurrently with proposed standards under various sections of
the CAA, including section 231.\239\ Comment has been taken on these
proposed findings as part of the notice and comment process for the
emission standards.\240\ However, there is no requirement that the
Administrator propose the endangerment and cause or contribute findings
concurrently with proposed standards and, most recently under section
231, the EPA made separate endangerment and cause or contribute
findings for GHGs before proceeding to set standards.
---------------------------------------------------------------------------
\239\ 81 FR at 54425 (Aug. 19, 2016).
\240\ See, e.g., Rulemaking for non-road compression-ignition
engines under section 213(a)(4) of the CAA, Proposed Rule at 58 FR
28809, 28813-14 (May 17, 1993), Final Rule at 59 FR 31306, 31318
(June 17, 1994); Rulemaking for highway heavy-duty diesel engines
and diesel sulfur fuel under sections 202(a) and 211(c) of the CAA,
Proposed Rule at 65 FR 35430 (June 2, 2000), and Final Rule at 66 FR
5002 (Jan. 18, 2001).
---------------------------------------------------------------------------
The Administrator is applying the rulemaking provisions of CAA
section 307(d) to this action, pursuant to CAA section 307(d)(1)(V),
which provides that the provisions of 307(d) apply to ``such other
actions as the Administrator may determine.'' \241\ Any subsequent
[[Page 62774]]
standard setting rulemaking under CAA section 231 will also be subject
to the notice and comment rulemaking procedures under CAA section
307(d), as provided in CAA section 307(d)(1)(F) (applying the
provisions of CAA section 307(d) to the promulgation or revision of any
aircraft emission standard under CAA section 231). Thus, these proposed
findings will be subject to the same procedural requirements that would
apply if the proposed findings were part of a standard-setting
rulemaking.
---------------------------------------------------------------------------
\241\ As the Administrator is applying the provisions of CAA
section 307(d) to this action under section 307(d)(1)(V), we need
not determine whether those provisions would apply to this action
under section 307(d)(1)(F).
---------------------------------------------------------------------------
B. Considerations for the Endangerment and Cause or Contribute Analyses
Under Section 231(a)(2)(A)
In the context of this proposal, the EPA understands section
231(a)(2)(A) of the CAA to call for the Administrator to exercise his
judgment and make two separate determinations: first, whether the
relevant kind of air pollution (here, lead air pollution) may
reasonably be anticipated to endanger public health or welfare, and
second, whether emissions of any air pollutant from classes of the
sources in question (here, any aircraft engine that is capable of using
leaded aviation gasoline), cause or contribute to this air
pollution.\242\
---------------------------------------------------------------------------
\242\ See CRR, 684 F.3d at 117 (explaining two-part analysis
under section 202(a)) (June 26, 2012).
---------------------------------------------------------------------------
This analysis entails a scientific judgment by the Administrator
about the potential risks posed by lead emissions to public health and
welfare. In this proposed action, the EPA is using the same approach in
making scientific judgments regarding endangerment as it has previously
described in the 2016 Findings, and its analysis is guided by the same
five principles that guided the Administrator's analysis in those
Findings.\243\
---------------------------------------------------------------------------
\243\ See, e.g., 81 FR 54422, 54434-55435 (Aug. 15, 2016).
---------------------------------------------------------------------------
Similarly, the EPA is taking the same approach to the cause or
contribute analysis as was previously explained in the 2016
Findings.\244\ For example, as previously noted, section 231(a)(2)(A)'s
instruction to consider whether emissions of an air pollutant cause or
contribute to air pollution makes clear that the Administrator need not
find that emissions from any one sector or class of sources are the
sole or even the major part of an air pollution problem.\245\ Moreover,
like the CAA section 202(a) language that governed the 2009 Findings,
the statutory language in section 231(a)(2)(A) does not contain a
modifier on its use of the term ``contribute.'' \246\ Unlike other CAA
provisions, it does not require ``significant'' contribution. Compare,
e.g., CAA sections 111(b); 213(a)(2), (4). Congress made it clear that
the Administrator is to exercise his judgment in determining
contribution, and authorized regulatory controls to address air
pollution even if the air pollution problem results from a wide variety
of sources.\247\ While the endangerment test looks at the air pollution
being considered as a whole and the risks it poses, the cause or
contribute test is designed to authorize the EPA to identify and then
address what may well be many different sectors, classes, or groups of
sources that are each part of the problem.\248\
---------------------------------------------------------------------------
\244\ See, e.g., 81 FR at 54437-54438 (September 4, 2013).
\245\ See, e.g., 81 FR at 54437-54438 (Aug. 15, 2016).
\246\ See, e.g., 81 FR at 54437-54438 (Aug. 15, 2016).
\247\ See 81 FR at 54437-54438 (Aug. 15, 2016).
\248\ See 81 FR at 54437-54438 (Aug. 15, 2016).
---------------------------------------------------------------------------
Moreover, as the EPA has previously explained, the Administrator
has ample discretion in exercising his reasonable judgment and
determining whether, under the circumstances presented, the cause or
contribute criterion has been met.\249\ As noted in the 2016 Findings,
in addressing provisions in section 202(a), the D.C. Circuit has
explained that the Act at the endangerment finding step did not require
the EPA to identify a precise numerical value or ``a minimum threshold
of risk or harm before determining whether an air pollutant
endangers.'' \250\ Accordingly, the EPA ``may base an endangerment
finding on `a lesser risk of greater harm . . . or a greater risk of
lesser harm' or any combination in between.'' \251\ As the language in
section 231(a)(2)(A) is analogous to that in section 202(a), it is
reasonable to apply this interpretation to the endangerment
determination under section 231(a)(2)(A).\252\ Moreover, the logic
underlying this interpretation supports the general principle that
under CAA section 231 the EPA is not required to identify a specific
minimum threshold of contribution from potentially subject source
categories in determining whether their emissions ``cause or
contribute'' to the endangering air pollution.\253\ The reasonableness
of this principle is further supported by the fact that section 231
does not impose on the EPA a requirement to find that such contribution
is ``significant,'' let alone the sole or major cause of the
endangering air pollution.\254\
---------------------------------------------------------------------------
\249\ See 81 FR at 54437-54438 (Aug. 15, 2016).
\250\ CRR, 684 F.3d at 122-123 (June 26, 2012).
\251\ CRR, 684 F.3d at 122-123. (quoting Ethyl Corp., 541 F.2d
at 18) (June 26, 2012).
\252\ 81 FR at 54438 (Aug. 15, 2016).
\253\ 81 FR at 54438 (Aug. 15, 2016).
\254\ 81 FR at 54438 (Aug. 15, 2016).
---------------------------------------------------------------------------
Finally, as also described in the 2016 Findings, there are a number
of possible ways of assessing whether air pollutants cause or
contribute to the air pollution which may reasonably be anticipated to
endanger public health and welfare, and no single approach is required
or has been used exclusively in previous cause or contribute
determinations under title II of the CAA.\255\
---------------------------------------------------------------------------
\255\ See 81 FR at 54462 (Aug. 15, 2016).
---------------------------------------------------------------------------
C. Regulatory Authority for Emission Standards
Though the EPA is not proposing standards in this action, should
the EPA finalize these findings, the EPA would then proceed to propose
emission standards under CAA section 231. As noted in Section III.A of
this document, section 231(a)(2)(A) of the CAA directs the
Administrator of the EPA to, from time to time, propose aircraft engine
emission standards applicable to the emission of any air pollutant from
classes of aircraft engines which in his or her judgment causes or
contributes to air pollution that may reasonably be anticipated to
endanger public health or welfare.
CAA section 231(a)(2)(B) further directs the EPA to consult with
the Administrator of the FAA on such standards, and it prohibits the
EPA from changing aircraft emission standards if such a change would
significantly increase noise and adversely affect safety. CAA section
231(a)(3) provides that after we provide notice and an opportunity for
a public hearing on standards, the Administrator shall issue such
standards ``with such modifications as he deems appropriate.'' In
addition, under CAA section 231(b), the EPA determines, in consultation
with the U.S. Department of Transportation (DOT), that the effective
date of any standard provides the necessary time to permit the
development and application of the requisite technology, giving
appropriate consideration to the cost of compliance.
Once the EPA adopts standards, CAA section 232 then directs the
Secretary of Transportation to prescribe regulations to ensure
compliance with the EPA's standards. Finally, section 233 of the CAA
vests the authority to promulgate emission standards for aircraft or
aircraft engines only in the federal government. States are preempted
from adopting or enforcing any standard respecting aircraft or aircraft
engine
[[Page 62775]]
emissions unless such standard is identical to the EPA's
standards.\256\
---------------------------------------------------------------------------
\256\ CAA Section 233 (Dec. 31, 1970).
---------------------------------------------------------------------------
IV. The Proposed Endangerment Finding Under CAA Section 231
A. Scientific Basis of the Endangerment Finding
1. Lead Air Pollution
Lead is emitted and exists in the atmosphere in a variety of forms
and compounds and is emitted by a wide range of sources.\257\ Lead is
persistent in the environment. Atmospheric transport distances of
airborne lead vary depending on its form and particle size, as
discussed in Section II.A of this document, with coarse lead-bearing
particles deposited to a greater extent near the source, while fine
lead-bearing particles can be transported long distances before being
deposited. Through atmospheric deposition, lead is distributed to other
environmental media, including soils and surface water bodies.\258\
Lead is retained in soils and sediments, where it provides a historical
record and, depending on several factors, can remain available in some
areas for extended periods for environmental or human exposure, with
any associated potential public health and public welfare impacts.
---------------------------------------------------------------------------
\257\ EPA (2013) ISA for Lead. Section 2.2. ``Sources of
Atmospheric Pb.'' p. 2-1. EPA, Washington, DC, EPA/600/R-10/075F,
2013.
\258\ EPA (2013) ISA for Lead. Executive Summary. ``Sources,
Fate and Transport of Lead in the Environment, and the Resulting
Human Exposure and Dose.'' pp. lxxviii-lxxix. EPA, Washington, DC,
EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
For purposes of this action, the EPA is proposing to define the
``air pollution'' referred to in section 231(a)(2)(A) of the CAA as
lead, which we also refer to as the lead air pollution in this
document.\259\
---------------------------------------------------------------------------
\259\ The lead air pollution that we are considering in this
proposed finding can occur as elemental lead or in lead-containing
compounds, and this proposed definition of the air pollution
recognizes that lead in air (whatever form it is found in, including
in inorganic and organic compounds containing lead) has the
potential to elicit public health and welfare effects. We note, for
example, that the 2013 Lead ISA and 2008 AQCD described the
toxicokinetics of inorganic and organic forms of lead and studies
evaluating lead-related health effects commonly measure total lead
level (i.e., all forms of lead in various biomarker tissues such as
blood).
---------------------------------------------------------------------------
2. Health Effects and Lead Air Pollution
As noted in Section II.A of this document, in 2013, the EPA
completed the Integrated Science Assessment for Lead which built on the
findings of previous AQCDs for Lead. These documents critically assess
and integrate relevant scientific information regarding the health and
welfare effects of lead and have undergone extensive critical review by
the EPA, the Clean Air Scientific Advisory Committee (CASAC), and the
public. As such, these assessments provide the primary scientific and
technical basis on which the Administrator is proposing to find that
lead air pollution is reasonably anticipated to endanger public health
and welfare.\260 261\
---------------------------------------------------------------------------
\260\ EPA (2013) ISA for Lead. EPA, Washington, DC, EPA/600/R-
10/075F, 2013.
\261\ EPA (2006) AQC for Lead. EPA, Washington, DC, EPA/600/R-5/
144aF, 2006.
---------------------------------------------------------------------------
As summarized in Section II.A of this document, human exposure to
lead that is emitted into the air can occur by multiple pathways.
Ambient air inhalation pathways include both inhalation of air outdoors
and inhalation of ambient air that has infiltrated into indoor
environments. Additional exposure pathways may involve media other than
air, including indoor and outdoor dust, soil, surface water and
sediments, vegetation and biota. While the bioavailability of air-
related lead is modified by several factors in the environment (e.g.,
the chemical form of lead, environmental fate of lead emitted to air),
as described in Section II.A of this document, it is well-documented
that exposures to air-related lead can result in increased blood lead
levels, particularly for children living near air lead sources, who may
have increased blood lead levels due to their proximity to these
sources of exposure.\262\
---------------------------------------------------------------------------
\262\ EPA (2013) ISA for Lead. Section 5.4. ``Summary.'' p. 5-
40. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
As described in the EPA's 2013 Lead ISA and in prior Criteria
Documents, lead has been demonstrated to exert a broad array of
deleterious effects on multiple organ systems. The 2013 Lead ISA
characterizes the causal nature of relationships between lead exposure
and health effects using a weight-of-evidence approach.\263\ We
summarize here those health effects for which the EPA in the 2013 Lead
ISA has concluded that the evidence supports a determination of either
a ``causal relationship,'' or a ``likely to be causal relationship,''
or for which the evidence is ``suggestive of a causal relationship''
between lead exposure and a health effect.\264\ In the discussion that
follows, we summarize findings regarding effects observed in children,
effects observed in adults, and additional effects observed that are
not specific to an age group.
---------------------------------------------------------------------------
\263\ The causal framework draws upon the assessment and
integration of evidence from across scientific disciplines, spanning
atmospheric chemistry, exposure, dosimetry and health effects
studies (i.e., epidemiologic, controlled human exposure, and animal
toxicological studies), and assessment of the related uncertainties
and limitations that ultimately influence our understanding of the
evidence. This framework employs a five-level hierarchy that
classifies the overall weight-of-evidence with respect to the causal
nature of relationships between criteria pollutant exposures and
health and welfare effects using the following categorizations:
causal relationship; likely to be causal relationship; suggestive
of, but not sufficient to infer, a causal relationship; inadequate
to infer the presence or absence of a causal relationship; and not
likely to be a causal relationship. EPA (2013) ISA for Lead.
Preamble Section. p. xliv. EPA, Washington, DC, EPA/600/R-10/075F,
2013.
\264\ EPA (2013) ISA for Lead. Table ES-1. ``Summary of causal
determinations for the relationship between exposure to Pb and
health effects.'' pp. lxxxiii-lxxxvii. EPA, Washington, DC, EPA/600/
R-10/075F, 2013.
---------------------------------------------------------------------------
The EPA has concluded that there is a ``causal relationship''
between lead exposure during childhood (pre and postnatal) and a range
of health effects in children, including the following: Cognitive
function decrements; the group of externalizing behaviors comprising
attention, increased impulsivity, and hyperactivity; and developmental
effects (i.e., delayed pubertal onset).\265\ In addition, the EPA has
concluded that the evidence supports a conclusion that there is a
``likely to be causal relationship'' between lead exposure and conduct
disorders in children and young adults, internalizing behaviors such as
depression, anxiety and withdrawn behavior, auditory function
decrements, and fine and gross motor function decrements.\266\
---------------------------------------------------------------------------
\265\ EPA (2013) ISA for Lead. Table ES-1. ``Summary of causal
determinations for the relationship between exposure to Pb and
health effects.'' p. lxxxiii and p. lxxxvi. EPA, Washington, DC,
EPA/600/R-10/075F, 2013.
\266\ EPA (2013) ISA for Lead. Table ES-1. ``Summary of causal
determinations for the relationship between exposure to Pb and
health effects.'' pp. lxxxiii-lxxxiv. EPA, Washington, DC, EPA/600/
R-10/075F, 2013.
---------------------------------------------------------------------------
Multiple epidemiologic studies conducted in diverse populations of
children consistently demonstrate the harmful effects of lead exposure
on cognitive function (as measured by decrements in intelligence
quotient [IQ], decreased academic performance, and poorer performance
on tests of executive function). These findings are supported by
extensively documented toxicological evidence substantiating the
plausibility of these findings in the epidemiological literature and
provide information on the likely mechanisms underlying these
neurotoxic effects.\267\
---------------------------------------------------------------------------
\267\ EPA (2013) ISA for Lead. Executive Summary. ``Effects of
Pb Exposure in Children.'' pp. lxxxvii-lxxxviii. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
Intelligence quotient is a well-established, widely recognized and
rigorously standardized measure of neurocognitive function which has
been
[[Page 62776]]
used extensively as a measure of the negative effects of exposure to
lead.268 269 Examples of other measures of cognitive
function negatively associated with lead exposure include measures of
intelligence and cognitive development and cognitive abilities, such as
learning, memory, and executive functions, as well as academic
performance and achievement.\270\
---------------------------------------------------------------------------
\268\ EPA (2013) ISA for Lead. Section 4.3.2. ``Cognitive
Function.'' p. 4-59. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
\269\ EPA (2006) AQC for Lead. Sections 6.2.2 and 8.4.2. EPA,
Washington, DC, EPA/600/R-5/144aF, 2006.
\270\ EPA (2013) ISA for Lead. Section 4.3.2. ``Cognitive
Function.'' p. 4-59. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
In summarizing the evidence related to neurocognitive impacts of
lead at different childhood lifestages, the 2013 Lead ISA notes that
``in individual studies, postnatal (early childhood and concurrent
[with IQ testing]) blood lead levels are also consistently associated
with cognitive function decrements in children and adolescents.'' \271\
The 2013 Lead ISA additionally notes that the findings from
experimental animal studies indicate that lead exposures during
multiple early lifestages and periods are observed to induce
impairments in learning, and that these findings ``are consistent with
the understanding that the nervous system continues to develop (i.e.,
synaptogenesis and synaptic pruning remains active) throughout
childhood and into adolescence.'' \272\ The 2013 Lead ISA further notes
that ``it is clear that lead exposure in childhood presents a risk;
further, there is no evidence of a threshold below which there are no
harmful effects on cognition from lead exposure,'' and additionally
recognizes uncertainty about the lead exposures that are part of the
effects and blood lead levels observed in epidemiologic studies
(uncertainties which are greater in studies of older children and
adults than in studies of younger children).\273\ Evidence suggests
that while some neurocognitive effects of lead in children may be
transient, some lead-related cognitive effects may be irreversible and
persist into adulthood,\274\ potentially affecting lower educational
attainment and financial well-being.\275\
---------------------------------------------------------------------------
\271\ EPA (2013) ISA for Lead. Section 1.9.4. ``Pb Exposure and
Neurodevelopmental Deficits in Children.'' p. 1-76. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
\272\ EPA (2013) ISA for Lead. Section 1.9.4. ``Pb Exposure and
Neurodevelopmental Deficits in Children.'' p. 1-76. EPA/600/R-10/
075F, 2013.
\273\ EPA (2013) ISA for Lead. Executive Summary. ``Effects of
Pb Exposure in Children.'' pp. lxxxvii-lxxxviii. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
\274\ EPA (2013) ISA for Lead. Section 1.9.5. ``Reversibility
and Persistence of Neurotoxic Effects of Pb.'' p. 1-76. EPA,
Washington, DC, EPA/600/R-10/075F, 2013.
\275\ EPA (2013) ISA for Lead. Section 4.3.14. ``Public Health
Significance of Associations between Pb Biomarkers and
Neurodevelopmental Effects.'' p. 4-279. EPA, Washington, DC, EPA/
600/R-10/075F, 2013.
---------------------------------------------------------------------------
The 2013 Lead ISA concluded that neurodevelopmental effects in
children were among the effects best substantiated as occurring at the
lowest blood lead levels, and that these categories of effects were
clearly of the greatest concern with regard to potential public health
impact.\276\ For example, in considering population risk, the 2013 Lead
ISA notes that ``[s]mall shifts in the population mean IQ can be highly
significant from a public health perspective''.\277\ Specifically, if
lead-related decrements are manifested uniformly across the range of IQ
scores in a population, ``a small shift in the population mean IQ may
be significant from a public health perspective because such a shift
could yield a larger proportion of individuals functioning in the low
range of the IQ distribution, which is associated with increased risk
of educational, vocational, and social failure'' as well as a decrease
in the proportion with high IQ scores.\278\
---------------------------------------------------------------------------
\276\ EPA (2013) ISA for Lead. Section 1.9.1. ``Public Health
Significance.'' p. 1-68. EPA, Washington, DC, EPA/600/R-10/075F,
2013.
\277\ EPA (2013) ISA for Lead. Executive Summary. ``Public
Health Significance.'' p. xciii. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
\278\ EPA (2013) ISA for Lead. Section 1.9.1. ``Public Health
Significance.'' p. 1-68. EPA, Washington, DC, EPA/600/R-10/075F,
2013.
---------------------------------------------------------------------------
With regard to lead effects identified for the adult population,
the 2013 Lead ISA concluded that there is a ``causal relationship''
between lead exposure and hypertension and coronary heart disease in
adults. The 2013 Lead ISA concluded that cardiovascular effects in
adults were those of greatest public health concern for adults because
the evidence indicated that these effects occurred at the lowest blood
lead levels, compared to other health effects, although the role of
past versus current exposures to lead is unclear.\279\
---------------------------------------------------------------------------
\279\ EPA (2013) ISA for Lead. Section 1.9.1. ``Public Health
Significance.'' p. 1-68. EPA, Washington, DC, EPA/600/R-10/075F,
2013.
---------------------------------------------------------------------------
With regard to evidence of cardiovascular effects and other effects
of lead on adults, the 2013 Lead ISA notes that ``[a] large body of
evidence from both epidemiologic studies of adults and experimental
studies in animals demonstrates the effect of long-term lead exposure
on increased blood pressure and hypertension.'' \280\ In addition to
its effect on blood pressure, ``lead exposure can also lead to coronary
heart disease and death from cardiovascular causes and is associated
with cognitive function decrements, symptoms of depression and anxiety,
and immune effects in adult humans.'' \281\ The extent to which the
effects of lead on the cardiovascular system are reversible is not
well-characterized. Additionally, the frequency, timing, level, and
duration of lead exposure causing the effects observed in adults has
not been pinpointed, and higher exposures earlier in life may play a
role in the development of health effects measured later in life.\282\
The 2013 Lead ISA states that ``[i]t is clear however, that lead
exposure can result in harm to the cardiovascular system that is
evident in adulthood and may also affect a broad array of organ
systems.'' \283\ In summarizing the public health significance of lead
on the adult population, the 2013 Lead ISA notes that ``small lead-
associated increases in the population mean blood pressure could result
in an increase in the proportion of the population with hypertension
that is significant from a public health perspective.'' \284\
---------------------------------------------------------------------------
\280\ EPA (2013) ISA for Lead. Executive Summary. ``Effects of
Pb Exposure in Adults.'' p. lxxxviii. EPA/600/R-10/075F, 2013.
\281\ EPA (2013) ISA for Lead. Executive Summary. ``Effects of
Pb Exposure in Adults.'' p. lxxxviii. EPA/600/R-10/075F, 2013.
\282\ EPA (2013) ISA for Lead. Executive Summary. ``Effects of
Pb Exposure in Adults.'' p. lxxxviii. EPA/600/R-10/075F, 2013.
\283\ EPA (2013) ISA for Lead. Executive Summary. ``Effects of
Pb Exposure in Adults.'' p. lxxxviii. EPA/600/R-10/075F, 2013.
\284\ EPA (2013) ISA for Lead. Executive Summary. ``Public
Health Significance.'' p. xciii. EPA, Washington, DC, EPA/600/R-10/
075F, 2013.
---------------------------------------------------------------------------
In addition to the effects summarized here, the EPA has concluded
there is a ``likely to be causal relationship'' between lead exposure
and both cognitive function decrements and psychopathological effects
in adults. The 2013 Lead ISA also concludes that there is a ``causal
relationship'' between lead exposure and decreased red blood cell
survival and function, altered heme synthesis, and male reproductive
function. The EPA has also concluded there is a ``likely to be causal
relationship'' between lead exposure and decreased host resistance,
resulting in increased susceptibility to bacterial infection and
suppressed delayed type hypersensitivity, and cancer.\285\
---------------------------------------------------------------------------
\285\ EPA (2013) ISA for Lead. Table ES-1. ``Summary of causal
determinations for the relationship between exposure to Pb and
health effects.'' pp. lxxxiv-lxxxvii. EPA, Washington, DC, EPA/600/
R-10/075F, 2013.
---------------------------------------------------------------------------
Additionally, the evidence is suggestive of lead exposure and some
additional effects. These include auditory function decrements and
[[Page 62777]]
subclinical atherosclerosis, reduced kidney function, birth outcomes
(e.g., low birth weight, spontaneous abortion), and female reproductive
function.\286\
---------------------------------------------------------------------------
\286\ EPA (2013) ISA for Lead. Table ES-1. ``Summary of causal
determinations for the relationship between exposure to Pb and
health effects.'' pp. lxxxiv-lxxxvi. EPA, Washington, DC, EPA/600/R-
10/075F, 2013.
---------------------------------------------------------------------------
The EPA has identified factors that may increase the risk of health
effects of lead exposure due to susceptibility and/or vulnerability;
these are termed ``at-risk'' factors. The 2013 Lead ISA describes the
systematic approach the EPA uses to evaluate the coherence of evidence
to determine the biological plausibility of associations between at-
risk factors and increased vulnerability and/or susceptibility. An
overall weight of evidence is used to determine whether a specific
factor results in a population being at increased risk of lead-related
health effects.\287\ The 2013 Lead ISA concludes that ``there is
adequate evidence that several factors--childhood, race/ethnicity,
nutrition, residential factors, and proximity to lead sources--confer
increased risk of lead-related health effects.'' \288\
---------------------------------------------------------------------------
\287\ EPA (2013) ISA for Lead. Chapter 5. ``Approach to
Classifying Potential At-Risk Factors.'' p. 5-2. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
\288\ EPA (2013) ISA for Lead. Section 5.4. ``Summary.'' p. 5-
44. EPA, Washington, DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
3. Welfare Effects and Lead Air Pollution
The 2013 Lead ISA characterizes the causal nature of relationships
between lead exposure and welfare effects using a five-level hierarchy
that classifies the overall weight-of-evidence.\289\ We summarize here
the welfare effects for which the EPA has concluded that the evidence
supports a determination of either a ``causal relationship,'' or a
``likely to be causal relationship,'' with exposure to lead, or that
the evidence is ``suggestive of a causal relationship'' with lead
exposure. The discussion that follows is organized to first provide a
summary of the effects of lead in the terrestrial environment, followed
by a summary of effects of lead in freshwater and saltwater ecosystems.
The 2013 Lead ISA further describes the scales or levels at which these
determinations between lead exposure and effects on plants,
invertebrates, and vertebrates were made (i.e., community-level,
ecosystem-level, population-level, organism-level or sub-organism
level).\290\
---------------------------------------------------------------------------
\289\ Causal determinations for ecological effects were based on
integration of information on biogeochemistry, bioavailability,
biological effects, and exposure-response relationships of lead in
terrestrial, freshwater, and saltwater environments. This framework
employs a five-level hierarchy that classifies the overall weight-
of-evidence with respect to the causal nature of relationships
between criteria pollutant exposures and health and welfare effects
using the categorizations described in the 2013 Lead NAAQS.
\290\ EPA (2013) ISA for Lead. Table ES-2. ``Schematic
representation of the relationships between the various MOAs by
which Pb exerts its effects.'' p. lxxxii. EPA, Washington, DC, EPA/
600/R-10/075F, 2013.
---------------------------------------------------------------------------
In terrestrial environments, the EPA determined that ``causal
relationships'' exist between lead exposure and reproductive and
developmental effects in vertebrates and invertebrates, growth in
plants, survival for invertebrates, hematological effects in
vertebrates, and physiological stress in plants.\291\ The EPA also
determined that there were ``likely to be causal relationships''
between lead exposure and community and ecosystem effects, growth in
invertebrates, survival in vertebrates, neurobehavioral effects in
invertebrates and vertebrates, and physiological stress in
invertebrates and vertebrates.
---------------------------------------------------------------------------
\291\ EPA (2013) ISA for Lead. Table ES-2. ``Summary of causal
determinations for the relationship between Pb exposure and effects
on plants, invertebrates, and vertebrates.'' p. xc. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
In freshwater environments, the EPA found that ``causal
relationships'' exist between lead exposure and reproductive and
developmental effects in vertebrates and invertebrates, growth in
invertebrates, survival for vertebrates and invertebrates, and
hematological effects in vertebrates. The EPA also determined that
there were ``likely to be causal relationships'' between lead exposure
and community and ecosystem effects, growth in plants, neurobehavioral
effects in invertebrates and vertebrates, hematological effects in
invertebrates, and physiological stress in plants, invertebrates, and
vertebrates.\292\
---------------------------------------------------------------------------
\292\ EPA (2013) ISA for Lead. Table ES-2. ``Summary of causal
determinations for the relationship between Pb exposure and effects
on plants, invertebrates, and vertebrates.'' p. xc. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
The EPA also determined that the evidence for saltwater ecosystems
was ``suggestive of a causal relationship'' between lead exposure and
reproductive and developmental effects in invertebrates, hematological
effects in vertebrates, and physiological stress in invertebrates.\293\
---------------------------------------------------------------------------
\293\ EPA (2013) ISA for Lead. Table ES-2. ``Summary of causal
determinations for the relationship between Pb exposure and effects
on plants, invertebrates, and vertebrates.'' p. xc. EPA, Washington,
DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
The 2013 Lead ISA concludes, ``With regard to the ecological
effects of lead, uptake of lead into fauna and subsequent effects on
reproduction, growth and survival are established and are further
supported by more recent evidence. These may lead to effects at the
population, community, and ecosystem level of biological organization.
In both terrestrial and aquatic organisms, gradients in response are
observed with increasing concentration of lead and some studies report
effects within the range of lead detected in environmental media over
the past several decades. Specifically, effects on reproduction,
growth, and survival in sensitive freshwater invertebrates are well-
characterized from controlled studies at concentrations at or near lead
concentrations occasionally encountered in U.S. fresh surface waters.
Hematological and stress related responses in some terrestrial and
aquatic species were also associated with elevated lead levels in
polluted areas. However, in natural environments, modifying factors
affect lead bioavailability and toxicity and there are considerable
uncertainties associated with generalizing effects observed in
controlled studies to effects at higher levels of biological
organization. Furthermore, available studies on community and
ecosystem-level effects are usually from contaminated areas where lead
concentrations are much higher than typically encountered in the
environment. The contribution of atmospheric lead to specific sites is
not clear and the connection between air concentration of lead and
ecosystem exposure continues to be poorly characterized.'' \294\
---------------------------------------------------------------------------
\294\ EPA (2013) ISA for Lead. ``Summary.'' p. xcvi. EPA,
Washington, DC, EPA/600/R-10/075F, 2013.
---------------------------------------------------------------------------
B. Proposed Endangerment Finding
The Administrator proposes to find, for purposes of CAA section
231(a)(2)(A), that lead air pollution may reasonably be anticipated to
endanger the public health and welfare. This proposal is based on
consideration of the extensive scientific evidence, described in this
section, that has been amassed over decades and rigorously peer
reviewed by CASAC.
V. The Proposed Cause or Contribute Finding Under CAA Section 231
A. Proposed Definition of the Air Pollutant
Under section 231, the Administrator is to determine whether
emissions of any air pollutant from any class or classes of aircraft
engines cause or contribute to air pollution which may reasonably be
anticipated to endanger public health or welfare. As in the 2016
Findings that the EPA made under
[[Page 62778]]
section 231 for greenhouse gases, in making this proposed cause or
contribute finding under section 231(a)(2), the Administrator first
defines the air pollutant being evaluated. The Administrator has
reasonably and logically considered the relationship between the lead
air pollution and the air pollutant when considering emissions of lead
from engines used in covered aircraft. The Administrator proposes to
define the air pollutant to match the proposed definition of the air
pollution, such that the air pollutant analyzed for contribution would
mirror the air pollution considered in the endangerment finding.
Accordingly, for purposes of this action, the Administrator is
proposing to define the ``air pollutant'' referred to in section
231(a)(2)(A) as lead, which we also refer to as the lead air pollutant
in this document.\295\ As noted in Section II.A.2 of this document,
lead emitted to the air from covered aircraft engines is predominantly
in particulate form as lead dibromide; however, some chemical compounds
of lead that are expected in the exhaust from these engines, including
alkyl lead compounds, would occur in the air in gaseous form.
---------------------------------------------------------------------------
\295\ The lead air pollutant we are considering in this proposed
finding can occur as elemental lead or in lead-containing compounds,
and this definition of the air pollutant recognizes the range of
chemical forms of lead emitted by engines in covered aircraft.
---------------------------------------------------------------------------
Under section 231(a), the Administrator is required to set
``emission standards applicable to the emission of any air pollutant''
from classes of aircraft engines that the Administrator determines
causes or contributes to air pollution that may reasonably be
anticipated to endanger public health or welfare. If the Administrator
makes a final determination under section 231 that the emissions of the
lead air pollutant from certain classes of aircraft engines cause or
contribute to air pollution that may reasonably be anticipated to
endanger public health and welfare, then he is called on to set
standards applicable to the emission of this air pollutant. The term
``standards applicable to the emission of any air pollutant'' is not
defined, and the Administrator has the discretion to interpret it in a
reasonable manner to effectuate the purposes of section 231. We
anticipate that the Administrator would consider a variety of factors
in determining what approach to take in setting the standard or
standards, and the EPA would provide notice and an opportunity to
comment on the proposed standards before finalizing them.
B. The Data Used To Evaluate the Proposed Cause or Contribute Finding
The Administrator's assessment of whether emissions from the
engines used in covered aircraft cause or contribute to lead air
pollution is informed by estimates of lead emissions from the covered
aircraft, lead concentrations in air at and near airports that are
attributable to lead emissions from piston engines used in covered
aircraft, and potential future conditions.
As used in this proposal, the term, ``covered aircraft'' refers to
all aircraft and ultralight vehicles equipped with covered engines
which, in this context, means any aircraft engine that is capable of
using leaded avgas. Examples of covered aircraft would include smaller
piston-powered aircraft such as the Cessna 172 (single-engine aircraft)
and the Beechcraft Baron G58 (twin-engine aircraft), as well as the
largest piston-engine aircraft--the Curtiss C-46 and the Douglas DC-6.
Other examples of covered aircraft would include rotorcraft, such as
the Robinson R44 helicopter, light-sport aircraft, and ultralight
vehicles equipped with piston engines. The vast majority of covered
aircraft are piston-engine powered.
In recent years, covered aircraft are estimated to be the largest
single source of lead to air in the U.S. Since 2008, as described in
Section II.A.2.b of this document, lead emissions from covered aircraft
are estimated to have contributed over 50 percent of all lead emitted
to the air nationally. The EPA estimates 470 tons of lead were emitted
by covered aircraft in 2017, comprising 70 percent of lead emitted to
air nationally that year.\296\ In approximately 1,000 counties in the
U.S., the EPA's emissions inventory identifies covered aircraft as the
sole source of lead emissions. Among the 1,872 counties in the U.S. for
which the inventory identifies multiple sources of lead emissions,
including engine emissions from covered aircraft, the contribution of
aircraft engine emissions ranges from 0.0006 to 0.26 tons per year,
comprising 0.0065 to 99.98 percent (respectively) of total lead
emissions to air in those counties from covered aircraft.\297\
---------------------------------------------------------------------------
\296\ The lead inventories for 2008, 2011 and 2014 are provided
in the EPA (2018b) Report on the Environment Exhibit 2.
Anthropogenic lead emissions in the U.S. Available at https://cfpub.epa.gov/roe/indicator.cfm?i=13#2. The lead inventories for
2017 are available at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data#dataq.
\297\ Airport lead annual emissions data used were reported in
the 2017 NEI. Available at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data. In addition
to the triennial NEI, the EPA collects from state, local, and Tribal
air agencies point source data for larger sources every year (see
https://www.epa.gov/air-emissions-inventories/air-emissions-reporting-requirements-aerr for specific emissions thresholds).
While these data are not typically published as a new NEI, they are
available publicly upon request and are also included in https://www.epa.gov/air-emissions-modeling/emissions-modeling-platforms,
which are created for years other than the triennial NEI years.
County estimates of lead emissions from non-aircraft sources used in
this action are from the 2019 inventory. There are 3,012 counties
and statistical equivalent areas where EPA estimates engine
emissions of lead occur.
---------------------------------------------------------------------------
Covered aircraft activity, as measured by the number of hours flown
nationwide, increased nine percent in the period from 2012 through
2019.\298\ General aviation activity, largely conducted by covered
aircraft, increased up to 52 percent at airports that are among the
busiest in the U.S.\299\ In future years, while piston-engine aircraft
activity overall is projected to decrease slightly, this change in
activity is not projected to occur uniformly across airports in the
U.S.; some airports are forecast to have increased activity by general
aviation aircraft, the majority of which is conducted by piston-engine
aircraft.\300\ Although there is some uncertainty in these projections,
they indicate that lead emissions from covered aircraft may increase at
some airports in the future.\301\
---------------------------------------------------------------------------
\298\ FAA. General Aviation and Part 135 Activity Surveys--CY
2019. Chapter 3: Primary and Actual Use. Table 1.3--General Aviation
and Part 135 Total Hours Flown by Aircraft Type 2008-2019 (Hours in
Thousands). Retrieved on Dec., 27, 2021 at https://www.faa.gov/data_research/aviation_data_statistics/general_aviation/CY2019/.
\299\ Geidosch. Memorandum to Docket EPA-HQ-OAR-2022-0389. Past
Trends and Future Projections in General Aviation Activity and
Emissions. June 1, 2022. Docket ID EPA-HQ-2022-0389.
\300\ Geidosch. Memorandum to Docket EPA-HQ-OAR-2022-0389. Past
Trends and Future Projections in General Aviation Activity and
Emissions. June 1, 2022. Docket ID EPA-HQ-2022-0389.
\301\ FAA TAF Fiscal Years 2020-2045 describes the forecast
method, data sources, and review process for the TAF estimates. The
documentation for the TAF is available at https://taf.faa.gov/Downloads/TAFSummaryFY2020-2045.pdf.
---------------------------------------------------------------------------
Additionally, engine emissions of lead from covered aircraft may
deposit in the local environment and, due to the small size of the
lead-bearing particles emitted by engines in covered aircraft, these
particles may disperse widely in the environment. Therefore, because
lead is a persistent pollutant in the environment, we anticipate
current and future emissions of lead from covered aircraft engines may
contribute to exposures and uptake by humans and biota into the future.
In evaluating the contributions of engine emissions from covered
aircraft
[[Page 62779]]
to lead air pollution, as defined in Section V.A of this document, the
EPA also considers lead concentrations in the ambient air--monitored
concentrations, modeled concentrations, and model-extrapolated
estimates of lead concentrations. Lead concentrations monitored in the
ambient air typically quantify lead compounds collected as suspended
particulate matter. The information gained from air monitoring and air
quality modeling provides insight into how lead emissions from piston
engines used in covered aircraft can affect lead concentrations in air.
As described in Section II.A.3 of this document, the EPA has
conducted air quality modeling at two airports and extrapolated modeled
estimates of lead concentrations to 13,000 airports with piston-engine
aircraft activity. These studies indicate that over a three-month
averaging time (the averaging time for the Lead NAAQS), the engine
emissions of lead from covered aircraft are estimated to contribute to
air lead concentrations to a distance of at least 500 meters downwind
from a runway.302 303 Additional studies have reported that
lead emissions from covered aircraft may have increased concentrations
of lead in air by one to two orders of magnitude at locations proximate
to aircraft emissions compared to nearby locations not impacted by a
source of lead air emissions.304 305 306
---------------------------------------------------------------------------
\302\ Carr et. al., 2011. Development and evaluation of an air
quality modeling approach to assess near-field impacts of lead
emissions from piston-engine aircraft operating on leaded aviation
gasoline. Atmospheric Environment, 45 (32), 5795-5804. DOI: https://dx.doi.org/10.1016/j.atmosenv.2011.07.017.
\303\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. Table 6. EPA-420-R-20-003, 2020.
Available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG52.pdf.
\304\ Carr et al., 2011. Development and evaluation of an air
quality modeling approach to assess near-field impacts of lead
emissions from piston-engine aircraft operating on leaded aviation
gasoline. Atmospheric Environment, 45 (32), 5795-5804. DOI: https://dx.doi.org/10.1016/j.atmosenv.2011.07.017.
\305\ Heiken et al., 2014. Quantifying Aircraft Lead Emissions
at Airports. ACRP Report 133. Available at https://www.nap.edu/catalog/22142/quantifying-aircraft-lead-emissions-at-airports.
\306\ Hudda et al., 2022. Substantial Near-Field Air Quality
Improvements at a General Aviation Airport Following a Runway
Shortening. Environmental Science & Technology. DOI: 10.1021/
acs.est.1c06765.
---------------------------------------------------------------------------
In 2008 and 2010, the EPA enhanced the lead monitoring network by
requiring monitors to be placed in areas with sources such as
industrial facilities and airports, as described further in Section
II.A.3 of this document.307 308 As part of this 2010
requirement to expand lead monitoring nationally, the EPA required a 1-
year monitoring study of 15 additional airports with estimated lead
emissions between 0.50 and 1.0 ton per year in an effort to better
understand how these emissions affect concentrations of lead in the air
at and near airports. Further, to help evaluate airport characteristics
that could lead to ambient lead concentrations that approach or exceed
the lead NAAQS, airports for this 1-year monitoring study were selected
based on factors such as the level of activity of covered aircraft and
the predominant use of one runway due to wind patterns. Monitored lead
concentrations in ambient air are highly sensitive to monitor location
relative to the location of the run-up areas for piston-engine aircraft
and other localized areas of elevated lead concentrations relative to
the air monitor locations.
---------------------------------------------------------------------------
\307\ 73 FR 66965 (Nov. 12, 2008).
\308\ 75 FR 81226 (Dec. 27, 2010).
---------------------------------------------------------------------------
The lead monitoring study at airports began in 2011. In 2012, air
monitors were placed in close proximity to the run-up areas at the San
Carlos Airport (starting on March 10, 2012) and the McClellan-Palomar
Airport (starting on March 16, 2012). The concentrations of lead
measured at both of these airports in 2012 were above the level of the
lead NAAQS, with the highest measured levels of lead in total suspended
particles over a rolling three-month average of 0.33 micrograms per
cubic meter of air at the San Carlos Airport and 0.17 micrograms per
cubic meter of air at the McClellan-Palomar Airport. These
concentrations violate the primary and secondary lead NAAQS, which are
set at a level of 0.15 micrograms per cubic meter of air measured in
total suspended particles, as an average of three consecutive monthly
concentrations.
In recognition of the potential for lead concentrations to exceed
the lead NAAQS in ambient air near the area of maximum concentration at
airports, the EPA further conducted an assessment of airports
nationwide, titled ``Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports'' and described in Section II.A.3 of
this document.\309\ The model-extrapolated lead concentrations
estimated in this study are attributable solely to emissions from
engines in covered aircraft operating at the airports evaluated and did
not include other sources of lead emissions to air. The EPA identified
four airports with the potential for lead concentrations above the lead
NAAQS due to lead emissions from engines used in covered aircraft.
---------------------------------------------------------------------------
\309\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports Table 6. EPA-420-R-20-003, 2020.
Available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG52.pdf.
---------------------------------------------------------------------------
Additional information regarding the contribution of engine
emissions of lead from covered aircraft to lead air pollution is
provided by the EPA's Air Toxics Screening Assessment. As described and
summarized in Section II.A.3 of this document, the EPA's Air Toxics
Screening Assessment estimates that piston engines used in aircraft
contribute more than 50 percent of the lead concentration in over half
of the census tracts in the U.S.\310\
---------------------------------------------------------------------------
\310\ EPA's 2017 AirToxScreen is available at https://www.epa.gov/AirToxScreen.
---------------------------------------------------------------------------
The EPA also notes that lead emissions from engines in covered
aircraft are present in three of the ten areas in the U.S. currently
designated as nonattainment for the 2008 lead NAAQS. These areas are
Arecibo, PR, and Hayden, AZ, each of which include one airport
servicing covered aircraft, and the Los Angeles County-South Coast Air
Basin, CA, which contains at least 22 airports within its nonattainment
area boundary.311 312 Although the lead emissions from
aircraft are not the predominant source of airborne lead in these
areas, the emissions from covered aircraft may increase ambient air
lead concentrations in these areas.
---------------------------------------------------------------------------
\311\ South Coast Air Quality Management District (2012)
Adoption of 2012 Lead SIP Los Angeles County by South Coast
Governing Board, p.3-11, Table 3-3. Available at https://www.aqmd.gov/home/air-quality/clean-air-plans/lead-state-implementation-plan. The South Coast Air Quality Management District
identified 22 airports in the Los Angeles County-South Coast Air
Basin nonattainment area; the Whiteman Airport is among those in the
nonattainment area and the EPA estimated activity at this airport
may increase lead concentrations to levels above the lead NAAQS in
the report, Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports. Table 7. EPA, Washington, DC, EPA-
420-R-20-003, 2020. Available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG52.pdf.
\312\ EPA provides updated information regarding nonattainment
areas at this website: https://www.epa.gov/green-book/green-book-lead-2008-area-information.
---------------------------------------------------------------------------
C. Proposed Cause or Contribution Finding for Lead
Taking into consideration the data and information summarized in
Section V of this document, the Administrator proposes to find that
engine emissions of the lead air pollutant from covered aircraft cause
or contribute to the lead air pollution that may reasonably be
anticipated to endanger public health and welfare. In reaching this
proposed conclusion, the Administrator notes that piston-engine
aircraft operate on leaded avgas. That operation emits lead-
[[Page 62780]]
containing compounds into the air, contributing to lead air pollution
in the environment. As explained in Section II.A of this document, once
emitted from covered aircraft, lead may be transported and distributed
to other environmental media, and present the potential for human
exposure through air and non-air pathways before the lead is removed to
deeper soils or waterbody sediments. In reaching this proposed finding,
the Administrator takes into consideration different air quality
scenarios in which emissions of the lead air pollutant from engines in
covered aircraft may cause or contribute to lead air pollution. Among
these considerations, he places weight on the fact that current lead
emissions from covered aircraft are an important source of air-related
lead in the environment and that engine emissions of lead from covered
aircraft are the largest single source of lead to air in the U.S. in
recent years. In this regard, he notes that these emissions contributed
over 50 percent of lead emissions to air starting in 2008, when
approximately 560 tons of lead was emitted by engines in covered
aircraft, and more recently, in 2017, when approximately 470 tons of
lead was emitted by engines in covered aircraft.\313\
---------------------------------------------------------------------------
\313\ The lead inventories for 2008, 2011 and 2014 are provided
in the U.S. EPA (2018b) Report on the Environment Exhibit 2.
Anthropogenic lead emissions in the U.S. Available at https://cfpub.epa.gov/roe/indicator.cfm?i=13#2. The lead inventories for
2017 are available at https://www.epa.gov/air-emissions-inventories/2017-national-emissions-inventory-nei-data#dataq.
---------------------------------------------------------------------------
Additionally, he takes into account the fact that in some
situations lead emissions from covered aircraft have contributed and
may continue to contribute to air quality that exceeds the lead NAAQS.
The NAAQS are standards that have been set to protect public health,
including the health of sensitive groups, with an adequate margin of
safety, and to protect public welfare from any known or anticipated
adverse effects associated with the presence of the pollutant in the
ambient air. For example, the EPA's monitoring data show that lead
concentrations at two airports, McClellan-Palomar and San Carlos,
violated the lead NAAQS. The EPA's model-extrapolated estimates of lead
also indicate that some U.S. airports may have air lead concentrations
above the NAAQS in the area of maximum impact from operation of covered
aircraft.\314\ Given that the lead NAAQS are established to protect
public health and welfare, contributions to concentrations that exceed
the lead NAAQS are of particular concern to the Administrator and add
support for the proposed conclusion that lead emissions from engines in
covered aircraft cause or contribute to the endangering air pollution.
---------------------------------------------------------------------------
\314\ EPA (2020) Model-extrapolated Estimates of Airborne Lead
Concentrations at U.S. Airports Table 7. EPA-420-R-20-003, 2020.
Available at https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100YG52.pdf.
---------------------------------------------------------------------------
The Administrator is also concerned about the likelihood for these
emissions to continue to be an important source of air-related lead in
the environment in the future, if uncontrolled. While recognizing that
national consumption of leaded avgas is forecast to decrease slightly
from 2026 to 2041 commensurate with overall piston-engine aircraft
activity, the Administrator also notes that these changes are not
expected to occur uniformly across the U.S. For example, he takes note
of the FAA forecasts for airport-specific aircraft activity out to 2045
that project decreases in activity by general aviation at some
airports, while projecting increases at other airports. Although there
is some uncertainty in these projections, they indicate that lead
emissions from covered aircraft may increase at some airports in the
future. Thus, even assuming that consumption of leaded avgas and
general aviation activity decrease somewhat overall, as projected, the
Administrator anticipates that current concerns about these sources of
air-related lead will continue into the future, without controls.
Accordingly, the Administrator is considering both current levels of
emissions and anticipated future levels of emissions from covered
aircraft. In doing so, the Administrator is proposing to find that
current levels cause or contribute to pollution that may reasonably be
anticipated to endanger public health and welfare. He also is taking
into consideration the projections that some airports may see increases
in activity while others see decreases, as well as the uncertainties in
these predictions. The Administrator therefore considers all this
information and data collectively to inform his judgment on whether
lead emissions from covered aircraft cause or contribute to endangering
air pollution.
Accordingly, for all the reasons described, the Administrator
proposes to conclude that emissions of the lead air pollutant from
engines in covered aircraft cause or contribute to the lead air
pollution that may reasonably be anticipated to endanger public health
and welfare.
VI. Statutory Authority and Executive Order Reviews
Additional information about these statutes and Executive Orders
can be found at https://www2.epa.gov/laws-regulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is a ``significant regulatory action'' because of the
cross-agency nature of this issue. Accordingly, it was submitted to the
Office of Management and Budget (OMB) for review under Executive Order
12866. This action proposes a finding that emissions of the lead air
pollutant from engines in covered aircraft cause or contribute to the
lead air pollution that may be reasonably anticipated to endanger
public health and welfare. Any changes made in response to OMB
recommendations have been documented in the docket.
B. Paperwork Reduction Act (PRA)
This action does not impose an information collection burden under
the PRA. The proposed endangerment and cause or contribute findings
under CAA section 231(a)(2)(A) do not contain any information
collection activities.
C. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. The proposed
endangerment and cause or contribute findings under CAA section
231(a)(2)(A) do not in-and-of-themselves impose any new requirements
but rather set forth the Administrator's proposed finding that
emissions of the lead air pollutant from engines in covered aircraft
cause or contribute to lead air pollution that may be reasonably
anticipated to endanger public health and welfare. Accordingly, this
action affords no opportunity for the EPA to fashion for small entities
less burdensome compliance or reporting requirements or timetables or
exemptions from all or part of the proposal.
D. Unfunded Mandates Reform Act (UMRA)
This action does not contain any unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538 and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local or Tribal governments or the private sector.
[[Page 62781]]
E. Executive Order 13132: Federalism
This action does not have federalism implications. It will not have
substantial direct effects on the states, on the relationship between
the national government and the states, or on the distribution of power
and responsibilities among the various levels of government.
F. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have Tribal implications as specified in
Executive Order 13175. The proposed endangerment and cause or
contribute findings under CAA section 231(a)(2)(A) do not in-and-of-
themselves impose any new requirements but rather set forth the
Administrator's proposed finding that emissions of the lead air
pollutant from engines in covered aircraft cause or contribute to lead
air pollution that may be reasonably anticipated to endanger public
health and welfare. Thus, Executive Order 13175 does not apply to this
action.
Tribes have previously submitted comments to the EPA noting their
concerns regarding potential impacts of lead emitted by piston-engine
aircraft operating on leaded avgas at airports on, and near, their
Reservation Land.\315\ The EPA plans to continue engaging with Tribal
stakeholders on this issue and will offer a government-to-government
consultation upon request.
---------------------------------------------------------------------------
\315\ See Docket ID Number EPA-HQ-OAR-2006-0735. The Tribes that
submitted comments were: The Bad River Band of Lake Superior Tribe
of Chippewa Indians, The Quapaw Tribe of Oklahoma, The Leech Lake
Band of Ojibwe, The Lone Pine Paiute-Shoshone Reservation, The Fond
du Lac Band of Lake Superior Chippewa, and The Mille Lacs Band of
Ojibwe.
---------------------------------------------------------------------------
G. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets E.O. 13045 (62 FR 19885, April 23, 1997) as
applying only to those regulatory actions that concern health or safety
risks, such that the analysis required under section 5-501 of the E.O.
has the potential to influence the regulation. This action is not
subject to E.O. 13045 because it does not propose to establish an
environmental standard intended to mitigate health or safety risks.
Although the Administrator considered health and safety risks as part
of the proposed endangerment and cause or contribute findings under CAA
section 231(a)(2)(A), the proposed findings themselves, if finalized,
would not impose a standard intended to mitigate those risks. While
this action is not subject to Executive Order 13045 in this scenario,
the Agency's Policy on Children's Health \316\ still applies. The
Administrator considered lead exposure risks to children as part of
this proposed endangerment finding under CAA section 231(a)(2)(A). This
action's discussion of the impacts of lead exposure on public health
and welfare is found in Section IV of this document, and specific
discussion with regard to children are contained in Supplemental
Information Section C, as well as Sections II.A.5, and IV of this
document. A copy of the documents pertaining to the impacts on
children's health from emissions of lead from piston-engine aircraft
that the EPA references in this action have been placed in the public
docket for this action (Docket EPA-HQ-OAR-2022-0389).
---------------------------------------------------------------------------
\316\ EPA (2021) EPA Policy on Children's Health. Available at
https://www.epa.gov/system/files/documents/2021-10/2021-policy-on-childrens-health.pdf.
---------------------------------------------------------------------------
H. Executive Order 13211: Actions Concerning Regulations That
Significantly Affect Energy Supply, Distribution or Use
This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution or use of energy. Further, we have concluded that this
action is not likely to have any adverse energy effects because the
proposed endangerment and cause or contribute findings under section
231(a)(2)(A) do not in-and-of themselves impose any new requirements
but rather set forth the Administrator's proposed finding that
emissions of the lead air pollutant from engines in covered aircraft
cause or contribute to lead air pollution that may be reasonably
anticipated to endanger public health and welfare.
I. National Technology Transfer and Advancement Act (NTTAA)
This action does not involve technical standards.
J. Executive Order 12898: Federal Actions To Address Environmental
Justice in Minority Populations and Low-Income Populations
The EPA believes this action will not have potentially
disproportionately high and adverse human health or environmental
effects on people of color, low-income, or indigenous populations
because this action does not affect the level of protection provided to
human health or the environment. The Administrator considered the
potential for lead exposure risks to people of color, low-income, and
indigenous populations as part of this proposed endangerment finding
under CAA section 231(a)(2)(A). This action's discussion of lead
exposure impacts on public health and welfare is found in Section IV of
this document. Specific discussion focused on environmental justice
with regard to people of color, low-income, and indigenous populations
are found in Supplemental Information Section D, as well as Sections
II.A.5, and Section IV of this document. A copy of the documents
pertaining to the EPA's analysis of potential environmental justice
concerns related to this action have been placed in the public docket
for this action (Docket EPA-HQ-OAR-2022-0389).
K. Determination Under Section 307(d)
Section 307(d)(1)(V) of the CAA provides that the provisions of
section 307(d) apply to ``such other actions as the administrator may
determine.'' Pursuant to section 307(d)(1)(V), the Administrator
determines that this action is subject to the provisions of section
307(d).
VII. Statutory Provisions and Legal Authority
Statutory authority for this action comes from 42 U.S.C. 7571, 7601
and 7607.
List of Subjects
40 CFR Parts 87 and 1031
Environmental protection, Air pollution control, Aircraft, Aircraft
engines.
40 CFR Part 1068
Environmental protection, Administrative practice and procedure,
Confidential business information, Imports, Motor vehicle pollution,
Penalties, Reporting and recordkeeping requirements, Warranties.
Michael S. Regan,
Administrator.
[FR Doc. 2022-22223 Filed 10-14-22; 8:45 am]
BILLING CODE 6560-50-P