FACT SHEET: NOTICE OF PROPOSED RULEMAKING FOR THE EPA RECONSIDERATION OF THE NATIONAL
AMBIENT AIR QUALITY STANDARDS FOR PARTICULATE MATTER

AIR QUALITY DESIGNATIONS AND IMPLEMENTATION

On January 6, 2023, the U.S. Environmental Protection Agency (EPA) announced a proposal to
strengthen the National Ambient Air Quality Standards (NAAQS) for fine particle pollution (PM2.5) by
revising the level of the primary (health-based) annual PM2.5 standard from 12 micrograms per cubic
meter (ng/m3) to within the range of 9.0 to 10.0 ng/m3. EPA proposed to retain the primary (health-
based) 24-hour PM2.5 standard, with its level of 35 ng/m3.

EPA also proposed to retain the primary (health-based) 24-hour PM10 standard, which provides public
health protection against exposures to coarse particles. The Administrator proposed to conclude that
current evidence does not call into question the adequacy of that standard.

In addition, EPA proposed not to revise the current secondary (welfare-based) standards for both PM2.5
and PM10 at this time. The Administrator proposed to conclude that the available evidence and
information do not call into question the adequacy of protection provided by the current secondary PM
standards for non-ecological effects (i.e., visibility, climate, and materials effects).

AIR QUALITY DESIGNATIONS

•	Improving air quality is a partnership between the federal government, States and Tribal Nations.
EPA will work closely with state, local and tribal air agencies to implement any new or revised PM2.5
NAAQS.

•	If EPA issues a new or revised PM2.5 NAAQS, the Clean Air Act directs EPA to take a series of NAAQS
implementation-related actions and requires states to deliver the anticipated public health benefits.
Meeting the standards in a given area would depend upon factors such as the level of PM2.5 in the
area and the emissions reduction measures needed to attain the NAAQS.

•	Generally, within 2 years of setting/revising a NAAQS, EPA designates all areas of the country as
attainment (meeting the standards), nonattainment (not meeting the standards), or unclassifiable
(not enough data to make a determination).

o Nonattainment areas include areas that are violating the standards and other nearby areas
with sources of emissions that contribute to those violations. EPA works closely with states
and tribes as it determines the initial area designations and the appropriate geographic
boundaries.

o For the PM2.5 NAAQS, the Clean Air Act provides that all nonattainment areas are classified
as "Moderate" at the outset. EPA would reclassify areas to "Serious" later in the
implementation process, under certain circumstances, such as continued failure to attain
the NAAQS within the required timeframe.


-------
•	Once designated, states with nonattainment areas must develop state implementation plans (SIPs)
showing how they will meet the new or revised standards.

o States with Moderate nonattainment areas are required to adopt and submit

nonattainment plan SIP submissions to EPA within 18 months of the effective date of
designation. These SIP submissions must meet applicable statutory and regulatory
requirements.

•	States with Moderate nonattainment areas must attain the PM2.5 NAAQS as
expeditiously as practicable, but by no later than the end of the sixth calendar year
after designations. Under certain circumstances, states may qualify for up to two 1-
year extensions.

o In the event of reclassification to Serious, states must meet additional statutory and
regulatory requirements in a new nonattainment plan SIP submission.

•	States with Serious nonattainment areas must attain the NAAQS as expeditiously as
practicable, but by no later than the end of the 10th calendar year following
designation. Under certain circumstances, states may qualify for one additional
extension of the attainment date up to 5 additional years.

o EPA's PM?.s SIP Requirements Rule provides additional details concerning Moderate and
Serious area plan requirements.

•	Tribes may, but are not required to, develop their own plans for nonattainment areas in Indian
country. Where necessary, EPA will develop plans for any tribal area that chooses not to develop its
own plans.

•	As a part of the nonattainment plan SIP development process, EPA encourages states to address
environmental justice (EJ) considerations. States are encouraged to involve community groups in the
SIP development process, and to use updated tools (such as EJScreen) to identify low income and
overburdened communities where control measures could be appropriately targeted.

•	Reductions in particle pollution from upcoming mobile, power plant and other air pollution federal
regulations could help some areas in reaching the proposed standards.

WILDLAND FIRE AND EXCEPTIONAL EVENTS CONSIDERATIONS

•	EPA recognizes the increasing challenges and human health impacts that wildland fire and smoke
pose in communities all around the country. EPA works closely with other federal agencies, state
and local health departments, tribal nations, and other partners to provide information, tools, and
resources to support communities in preparing for, responding to, and avoiding health impacts from
wildland fire and smoke.

•	EPA will continue to support states in managing the impacts of wildland fire and smoke on
attainment of the national ambient air quality standards for PM. The Clean Air Act and the
Exceptional Events Rule provide a framework for addressing air quality data impacted by exceptional


-------
events in the context of certain regulatory decisions, including designations regarding which areas
have attained the NAAQS. Both the Exceptional Events Rule and the 2016 PM2.5 State
Implementation Plan Requirements Rule address fire-related emissions, including emissions from
wildfires and prescribed fires on wildland. EPA has also issued detailed guidance on how states can
seek to exclude data influenced by such events under the Exceptional Events Rule.

•	The Exceptional Events Rule and the 2016 PM2.5 State Implementation Plan Requirements Rule have
frameworks in place to address emissions from wildland fires, including emissions from both
wildfires and prescribed fires on wildland. EPA has issued detailed guidance on the topics of wildfire
and prescribed fire on wildland, providing information on how states can seek exclusion of data
influenced by such events under the Exceptional Events Rule.

•	More information on exceptional events demonstration submission deadlines can be found in Table
2 to 40 CFR section 50.14(c)(2)(vi) - "Schedule for Initial Notification and Demonstration Submission
for Data Influenced by Exceptional Events for Use in Initial Area Designations"

•	In addition, EPA acknowledges that federal, state and Tribal agency partners, as well as other
stakeholders, view the use of prescribed fire as an important tool for reducing wildfire risk and the
severity of wildfires and wildfire smoke. EPA guidance issued pursuant to the Exceptional Events
Rule provides information regarding air quality impacts associated with prescribed fire on wildland,
approaches to mitigate the smoke impacts of such prescribed fires, and procedures for seeking the
exclusion of air quality data that is influenced by prescribed fire on wildland. EPA supports the use
of these Exceptional Events Rule provisions by state and Tribal air agencies, when needed.

•	Going forward, EPA is committed to partnering with federal land managers and working with states,
Tribes, air quality management districts, and other stakeholders to provide the necessary tools and
resources to engage in responsible wildfire risk reduction activities while ensuring attainment and
maintenance of air quality standards to protect public health and welfare under the Clean Air Act.
EPA intends to engage through opportunities such as the Wildland Fire Leadership Council to
enhance communications and understanding about air quality impacts from smoke generally and on
the particulate matter air quality standards, among federal agencies and other key stakeholders.
EPA is also continuing to review its existing Exceptional Events wildland fire-related tools and
information to identify opportunities to clarify or otherwise improve access to information and
resources.

ADDITIONAL BACKGROUND

• In August 2016, EPA published the PM? s SIP Requirements Rule to apply to all existing and future
PM2.5 NAAQS.


-------
•	The PM2.5 SIP Requirements Rule addresses a number of important nonattainment area planning
issues, including clarifying SIP due dates and attainment date extension criteria, the process for
determining control strategies, and provisions and definitions related to the Nonattainment New
Source Review permitting program.

•	The PM2.5 SIP Requirements Rule also includes environmental justice considerations in the context
of PM2.5 nonattainment area planning. EPA encourages states to take actions to address
environmental justice concerns, such as increasing opportunities for meaningful involvement by
community groups in SIP development and using updated tools (such as EJScreen) to identify low
income and overburdened communities where additional monitoring may be needed, and where
control measures can be targeted.

•	In this action, EPA is not proposing changes to the PM2.5 SIP Requirements Rule. However,
commenters are encouraged to share information on how states might develop implementation
plans that encourage early reductions as well as reductions that facilitate or amplify reductions
benefiting overburdened communities. Following promulgation of a final NAAQS, the EPA may
consider whether additional guidance on the topic of environmental justice and PM2.5
implementation is appropriate, beyond what is already included in the existing PM2.5 SIP
Requirements.

FOR MORE INFORMATION

•	For more information on particle pollution and to read the proposed action, visit
https://www.epa.gov/pm-pollution

•	For more information on state implementation planning requirements, visit
https://www.epa.gov/pm-pollution/pm25-naaqs-final-sip-requirements-rule-iuly-2016

•	For more information on the Exceptional Events Rule and related guidance, visit
https://www.epa.gov/air-qualitv-analysis/treatment-air-qualitv-data-influenced-exceptional-events-
homepage-exceptional

•	EPA has regulated particle pollution since 1971. The agency has revised the standards four times -
in 1987, 1997, 2006 and 2012 - to ensure they continue to protect public health and welfare. A
table of historical PM standards is available at
http://www.epa.gOv/ttn/naaqs/standards/pm/s pm historv.html


-------