Amicus Curiae Brief — Chamber of Commerce, et al., Petitioners v. Environmental Protection Agency, et al.

Nos. 26-277, 26-298







et al.

Petitioners,





et al.

Respondents.





et al.

Petitioners,





et al.

Respondents.



On Petitions for Writ of Certiorari to the

United States Courts of Appeals

for the District of Columbia Circuit



BRIEF OF THE MIDWEST OZONE GROUP

AS AMICUS CURIAE

IN SUPPORT OF PETITIONERS







Counsel of Record

















WILSON-EPES PRINTING CO., INC. – (202) 789-0096 – WASHINGTON, D.C. 20002

i

TABLE OF CONTENTS

Page

TABLE OF AUTHORITIES.......................................iii

INTRODUCTION AND INTEREST OF AMICUS

CURIAE ....................................................................... 1

SUMMARY OF ARGUMENT ..................................... 2

REASONS FOR GRANTING THE PETITIONS ……5

I.

The D.C. Circuit decision grants deference to

action that is not well-reasoned resulting in

significant costs, attainability and feasibility

impacts not authorized by the Clean Air

Act………………………………………..……….. 5

II.

Lowering The Annual Particulate Matter Standard

Will Result In Significant Costly Implications For

Permitting Sources And Source Sectors In The

United States Economy That Are Already

Stressed .............................................................. 8

III.

The PM2.5 NAAQS At 9.0 µg/m3 Is Not Attainable

Nor Feasible for Much of the Nation……………13

A. There Are Significant Problems With The

Updated Modeling Platform Used To Project

Attainment For 9.0 µg/m3 Annual Primary

PM2.5 Standard….. ...................................... 14

ii

B. EPA’s PM2.5 NAAQS Revision Fails To

Consider The Impact Of Its Data Adjustments

To The Monitoring Requirement Revisions

Finalized

In

Its

PM2.5

NAAQS

Reconsideration .......................................... 17

IV.

EPA’s Failure to Consider the Disparate Health

Effects

of

Speciated

PM2.5

Particles

Demonstrates Lack Of Thorough Review

……………………………..………………………18

CONCLUSION .......................................................... 20

iii

TABLE OF AUTHORITIES

Cases:

Page(s)

Loper Bright v. Raimondo, 603 U.S. 369 (2024)……….2

Ohio v. EPA, 603 U.S. 279 (2024)………....……..……..16

Michigan v. EPA, 576 U.S. 743, 752 (2015)………...5, 18

Federal Statutes:

CAA § 101(c), 42 U.S. Code § 7401(c)………………… . 8

CAA § 108, 42 U.S. Code § 7408 ................................... 5

CAA § 109, 42 U.S. Code § 7409 .... ………………..2,5-6

Federal Register:

89 Fed. Reg. 16,202 (Mar. 6, 2024)……….……..….1,5-8

89 Fed. Reg. 42,874 (May 16, 2024)……..…………….17

iv

Miscellaneous:

Air & Waste Management Association, EM Magazine

May 2023),

https://www.awma.org/emmay23 ............................. 10

EPA,

Final

Regulatory

Impact

Analysis

Reconsideration of the National Ambient Air Quality

Standards (Jan. 2024),

https://www.epa.gov/system/files/documents/202402/naaqspm_reconsideration_ria_final.pdf...................

.........................................................................6-7, 13-14

EPA, Final Rule 2018 Modeling Platform (Feb. 6,

2024),

https://www.epa.gov/air-emissions-modeling/2018v2emissions-modeling-platform .............................. 14-15

EPA, Policy Assessment for the Review of the National

Ambient Air Quality Standards for Particulate Matter

(Jan. 2020),

https://www.regulations.gov/document/EPA-HQOAR-2015-0072-1583. …...........................................7-8

EPA, Prevention of Significant Deterioration Basic

Information (Dec. 15, 2025),

https://www.epa.gov/nsr/prevention-significantdeterioration-basic-information. ............................... 13

v

EPA, Proposed Rule 2016 Modeling Platform (Jan.

2023),

https://www.epa.gov/air-emissions-modeling/2016v3platform. .................................................................... 14

EPA, Regulatory Impact Analysis for the Proposed

Reconsideration of the National Ambient Air Quality

Standards for Particulate Matter (Dec. 2022),

https://www.epa.gov/system/files/documents/202301/naaqs-pm_ria_proposed_2022-12.pdf ……………14

EPA, Responses to Significant Comments on the 2023

Proposed Rule for the Reconsideration of the National

Ambient Air Quality Standards for Particulate Matter

(Mar. 6, 2024),

https://www.regulations.gov/document/EPA-HQOAR-2015-0072-6010 .............................................7,19

EPA, Summary of and Responses to Public Comments

on the EPA’s Plan to Update PM2.5 Data from

T640/T640X PM Mass Monitors (May 13, 2024),

https://www.regulations.gov/document/EPA-HQOAR-2023-0642-0032 ............................................... 18

Midwest Ozone Group, Comments on Proposed

Reconsideration of National Ambient Air Quality

Standard for Particulate Matter (Mar. 28, 2023),

https://www.regulations.gov/document/EPA-HQOAR-2015-0072-2093....................................................6

vi

Texas Commission on Environmental Quality

Comments On Draft Integrated Review Plan for the

National Ambient Air Quality Standards for

Particulate Matter (Jun. 26, 2016),

https://www.regulations.gov/document/EPA-HQOAR-2015-0072-0008. .......................................... 18-19

Texas

Public

Policy

Foundation

comments

On EPA’s proposal to reconsider the PM2.5 NAAQS

(Feb. 21, 2023),

https://www.regulations.gov/document/EPA-HQ-OAR2015-0072-1812............................................................19

The Nature Conservancy comments On the Draft

Integrated Review Plan for the National Ambient Air

Quality Standards for Particulate Matter (Mar. 28,

2023),

https://www.regulations.gov/document/EPA-HQ-OAR2015-0072-2219...........................................................19

1

INTRODUCTION AND

INTEREST OF AMICUS CURIAE1

The Midwest Ozone Group is a continuing

association of organizations and individual entities

operated to promote its members’ interests concerning

air emissions and air quality. The Midwest Ozone

Group has been engaged with the federal regional

circuit courts and the United States Supreme Court

concerning the federal Clean Air Act (42 U.S. Code

§7401 et seq.) national ambient air quality standards

(NAAQS) development and implementation for over 30

years. The Midwest Ozone Group has committed its

resources to identifying and communicating about the

unique legal, scientific and technical issues and facts

that inform implementation of the Clean Air Act, all of

which will be the focus of this amicus brief.

The perspective of the Midwest Ozone Group

will illustrate the practical consequences of the D.C.

Circuit’s failure to effectively apply the Clean Air Act’s

thorough review requirement to the promulgation of

the fine particulate (PM2.5) NAAQS (89 Fed. Reg.

16,202 March 6, 2024) (Final Rule or PM2.5 NAAQS)

that is before the Court in this case. The Clean Air Act

does not authorize U.S. Environmental Protection

Agency (EPA) to shift the NAAQS standard by glancing

at a subset of preferred science. It instead requires a

1 All parties, including counsel for Respondents, received timely

notice of the intent of the Midwest Ozone Group to file this brief

under Rule 37(2)(a). Pursuant to Supreme Court Rule 37.6,

amicus curiae states that no counsel for any party, aside from

amicus curiae, its members, or its counsel, made any monetary

contribution intended to fund the preparation or submission of

this brief.

2

thorough review of all of the factors that must be

considered in the development of the NAAQS. EPA’s

cavalier dismissal of the significant impacts to include

costs of a suddenly changed NAAQS on non-attainment

counties, the nation’s economy, and affected sources is

based on agency hubris rather than lawful policy. The

comprehensive follow–on actions derived from the

Clean Air Act require research, design, installation,

air quality modeling, permit development, operational

changes and economic modification. In this case, the

Final Rule lost sight of the Clean Air Act.

The petitions for writ of certiorari filed by the

Commonwealth of Kentucky and the State of West

Virginia, et al., and by the Chamber of Commerce of the

United States, et al., correctly identify the cost and

thorough review factors required in EPA’s

promulgation of the Final Rule. The petitions raise for

review the failure of the D.C. Circuit to recognize Clean

Air Act statutory requirements for agency action

resulting in the urgent need for vacatur of the Final

Rule. The Court should grant the petitions.

Midwest Ozone Group incorporates in this brief

the petitioners’ briefs and offers the following

additional support for granting the petitions and

vacatur of the Final Rule.

SUMMARY OF ARGUMENT

“Thorough review” is the standard set for EPA by

section 109(d) of the Clean Air Act and an off-cycle revision

must be well-reasoned. Loper Bright, Enterprises v

Raimondo, 603 U. S. 369 (2024). This brief focuses on some

of the technical problems with the non-thorough process

that EPA used in the rule under review in this very case,

3

further illustrating how important it is that EPA perform

a “thorough review”.

EPA’s PM2.5 NAAQS rulemaking relied upon a

2016 emissions modeling platform in the proposed rule, yet

in the adoption of the Final Rule, a 2018 modeling platform

was utilized. The result is that the revised PM2.5 NAAQS

in the Final Rule is based on defective data and flaws that

were identified by Midwest Ozone Group in the record of

the rulemaking. Midwest Ozone Group takes the

position that this Court should grant the petitions

seeking to vacate the revised PM2.5 NAAQS rulemaking

because it will broadly sow significant rulemaking

follow–on actions that require investment of public and

private monies to implement a Clean Air Act program

that is based on improper, erroneous, and inconsistent

data.

One result of EPA’s failure is the revised PM2.5

NAAQS diminishes “headroom” or air quality

increments allowing for management of emissions

within a geographic area that meet the standard.

Those areas, which were already attaining the PM 2.5

NAAQS, now have limited increments between

ambient concentration levels and the improperly

revised PM2.5 NAAQS to manage costly Clean Air Act

actions such as state implementation plan

development, permitting, and prevention of economic

development.

The revised PM2.5 NAAQS will harm many.

More counties across the country will be in

nonattainment status that were incorrectly predicted

by the modeling used to support the Final Rule and

thus those counties are subject to additional costly

emission control requirements and investments.

Consequently, more facilities will be required to

decrease emissions to meet the ill-derived standard,

4

which will be an expense of time and money for all

stakeholders. The revised PM2.5 NAAQS will increase

the business cost of manufacturing and industrial

operations, stunting economic stability. For example,

new facilities and those undergoing major

modifications will have to clear additional agency

implementation hurdles and invest in new

engineering, equipment, and permitting. The Final

Rule is silent about the reality of implementing the

hastily changed PM2.5 NAAQS.

Inconsistent data and flawed projections derived

from a modeling platform will drive unjustified actions.

For example, the platforms rely on data reporting

inconsistencies that further undermine the integrity of

the science and technology supporting the PM2.5

NAAQS.

In addition, the Final Rule failed to include the

biased data adjustment consistent with EPA policy.

Monitoring data impacted by bias will improperly

characterize the air quality, but the Final Rule did not

account for that bias. Rather, the Final Rule

confirmed the bias of historical data taking no action,

therefore setting up a false conclusion about air

quality and statutorily required nonattainment

designations.

Stunningly, the revised PM2.5 NAAQS is not the

product of the Clean Air Act that requires a reasoned

process that effectively manages problematic data.

The petitioners’ questions presented focus on the

urgent NAAQS issues of “thorough review”, costs,

feasibility and attainability and the Court must grant

review.

The following facts and technical data are

provided to illustrate the scale of the real-world

5

consequences of the revised and improperly

promulgated rule and the impact of the failure of the

D.C. Circuit to recognize those statutory errors.

REASONS FOR GRANTING THE PETITIONS

The revised PM2.5 NAAQS before the Court

should have been vacated for a variety of reasons

including failure to consider the waterfall of events the

Clean Air Act requires with each new NAAQS. Each

event expands the adverse impact of an improperly

derived NAAQS. To be a standard that is achievable, a

NAAQS must necessarily be based on sound technical

data and science. The Clean Air Act does not tolerate

the failure of the Final Rule to consider the numerous

requirements and obligations imposed by the revised

PM2.5 NAAQS on regulated entities and others.

I.

The D.C. Circuit decision grants

deference to action that is not wellreasoned resulting in significant costs,

attainability and feasibility impacts

not authorized by the Clean Air Act.

The Clean Air Act sections 108 and 109 provide

a whether and how assessment process to be followed

for the promulgation of a NAAQS and for review to an

existing NAAQS. In the Final Rule, the agency

unlawfully concluded its action did not require

assessment of costs, attainability, or technical

feasibility. 89 Fed Reg. 16,202 at 16,205-6. The agency

must, however, be held to a reasoned decision-making

standard consistent with Michigan v. EPA, 576 U.S.

743, at 752 (2015). By failing to properly implement the

6

Clean Air Act, the revised PM2.5 NAAQS imposes on

Midwest Ozone Group and all other stakeholders a

litany of obligations including research, design, and

installation of control measures, air quality modeling,

permitting, operational changes and economic

modification

to

business

operations.

https://www.regulations.gov/document/EPA-HQ-OAR2015-0072-2093 at 11-13. EPA’s abbreviated and

dismissive process for reconsideration of the PM2.5

NAAQS is not reflective of Section 109 congressional

directives and is not an appropriate consideration of all

of the relevant factors. Id.

EPA’s varied statements about this revised

PM2.5 NAAQS demonstrate its hollow attempt at a

show of reasoned decision making. EPA confirms its

Final Rule as an “economically significant regulatory

action” as submitted to The Office of Management and

Budget for review. EPA also asserts that 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.” 89 Fed. Reg. 16,202 at

16,374. The exercise of noting “significance” as defined

by definitions not relevant to Section 109, does not

substitute for the need to assess all real-world

consequences found within technically measurable

metrics of factors, cost, attainability, and feasibility.

EPA’s Regulatory Impact Analysis indicates the

annualized controls costs are estimated at 593.8 million

dollars. EPA, Final Regulatory Impact Analysis

Reconsideration of the National Ambient Air Quality

Standards,

at

14

(Jan.

2024),

https://www.epa.gov/system/files/documents/202402/naaqs_pm_reconsideration_ria_final.pdf

(“Final

RIA”). To illustrate the areas where emissions reductions

will be required to meet the revised standard, EPA lists

7

52 counties located across the country that will need

PM2.5 emissions reductions: twelve in Eastern States,

seven in Southeast States, ten Western States, and

twenty-three in California. Id. at 10. However, the

agency is quick to note that its Regulatory Impact

Analysis was done for information purposes only, and

that the Final Rule was not based on consideration of

such information or analyses – illustrating a

fundamental defect in the Final Rule. 89 Fed. Reg.

16,202 at 16,206. EPA, Responses to Significant

Comments on the 2023 Proposed Rule for the

Reconsideration of the National Ambient Air Quality

Standards for Particulate Matter, (Mar. 6, 2024),

https://www.regulations.gov/document/EPA-HQOAR-2015-0072-6010 at 118-119. EPA tosses to the

states and others the burden of implementation and

therefore resource expenditures:

The action does not prescribe specific pollution

control strategies by which these ambient

standards and monitoring revisions will be met.

Such strategies will be developed by states on a

case-by-case basis, and the EPA cannot predict

whether the control options selected by states

will include regulations on energy suppliers,

distributors, or users. Thus, the EPA concludes

that this proposal does not constitute a

significant energy action as defined in

Executive Order 13211.

89 Fed. Reg. 16,202 at 16,374.

This narrative turns a blind eye to the expansive

list of counties and sources this Rule will engage as found

in the Policy Assessment. EPA, Policy Assessment for the

Review of the National Ambient Air Quality Standards

for

Particulate

Matter.

(Jan.

2020).

https://www.regulations.gov/document/EPA-HQ-OAR-

8

2015-0072-1583 (“Policy Assessment”) at 2–3. The types

of impacted anthropogenic sources of PM2.5 include both

stationary (e.g., fuel combustion for electricity production

and other purposes, industrial processes, agricultural

activities) and mobile (e.g., diesel- and gasoline-powered

highway vehicles and other engine-driven sources)

sources. Id. Begging the question about how states and

sources will control natural sources of PM2.5 to meet

the new NAAQS, the Final Rule lists dust from the

wind erosion of natural surfaces, sea salt, wildfires,

and biological particles such as bacteria and pollen. Id.

Wildland fire, which encompasses both wildfire and

prescribed fire, accounts for over 44% of emissions of

primary PM2.5 emissions. See 89 Fed. Reg. 16,202 at

16,214.

The quandary created with this revised PM2.5

NAAQS leads the nation to that which is

unachievable. EPA has taken the Clean Air Act to a

place where failure is the inevitable result. The Clean

Air Act, however, has the stated primary goal “to

encourage or otherwise promote reasonable Federal,

State, and local government actions. . .” CAA § 101(c).

II.

Lowering The Annual Particulate

Matter Standard Will Result In

Significant Costly Ramifications For

Permitting Sources And Source Sectors

In The United States Economy That Are

Already Stressed.

The following technical aspects of the Final

Rule illustrate how revision of a NAAQS without a

thorough review results in unjustified public and

private investments.

9

EPA’s 2032 air quality modeling projected

that there are 119 monitored counties in

nonattainment with the new revised PM2.5 NAAQS of

9.0 µg/m3 using annual PM2.5 2022 design values

(“DVs”). EPA also predicted the number of monitored

nonattainment counties would decrease to 52 (47%

rate of success of attainment) according to EPA’s 2032

air quality modeling. Final RIA at 10. The following

Figure 1 compares the EPA map of the 52 predicted

nonattainment counties, with a map that illustrates

the significant in number of affected counties when all

counties in Core Based Statistical Areas associated

with the violating monitors are included.

The result is that in 2032, the number of

counties projected to be in violation of a 9.0 µg/m3

standard increases from 52 to 187 counties. Id. All

these counties, if designated, would be subject to

additional emission control requirements to be

included in the implementation plans prepared by the

states for EPA review.

Such plans would require lower emissions at

multiple facilities within the nonattainment area and

a review, including possible retrofit of new controls for

existing sources. At these locations, multiple decisions

by agencies and sources will need to be considered

regarding cost of control, both existing and retrofit, as

well as the remaining useful life of each facility.

10

Figure 1. Monitored counties and expanded Core

Based

Statistical

Areas

modeled

3

by EPA in nonattainment of the 9.0 µg/m NAAQS

in 2032.

Major new projects, including new or planned

facilities and modifications to existing facilities, will

require controls to meet the more stringent “Lowest

Achievable Emission Rate” instead of “Best Available

Control Technology” controls. Emissions offsets will

also be required, not only for directly emitted

particulate matter, but also for pollutants that can

create particulate matter in the atmosphere (e.g.,

nitrogen dioxide and sulfur dioxide). An immediate

impact of a lower PM2.5 NAAQS is that new or

expanded manufacturing and other industrial projects

may become too costly in areas defined as

nonattainment and either not be pursued, or projects

may be relocated to attainment areas. Based on the

current projections, large swaths of the country will be

impacted. 2

2 Air & Waste Management Association, EM Magazine (May

2023), https://www.awma.org/emmay23

11

In areas that are in attainment, but close (1–3

µg/m3) to the 9.0 µg/m3 standard, industry will also need

to consider how close their area is to the new PM2.5

NAAQS. There will be areas that meet the standard but

have

limited

“headroom”

between

ambient

concentration levels and revised PM2.5 NAAQS.

Headroom here is defined as the amount of remaining

PM2.5 concentration (in µg/m3) from measured or

modeled conditions to the 9.0 µg/m3 NAAQS

nonattainment threshold. For example, with the annual

PM2.5 NAAQS set at 9.0 µg/m3, a county with a design

value of 8.0 µg/m3, would have headroom of 1.1 µg/m3

(9.1 – 8.0 µg/m3).

The following Figure 2 presents a continental

U.S. scale map of county-based headroom calculations

for the NAAQS at 9.0 µg/m3. To generate these metrics,

the maximum PM2.5 DVs from preliminary 2021– 2023

were used to represent each monitored county or

associated county within Core Based Statistical Areas.

Values were calculated for non-monitored counties

using a geospatial statistical interpolation that is used

to estimate non-monitored county values using an

inverse-distance

weighted

averaging

method.

Headroom was calculated as PM2.5 concentration

(µg/m3) remaining compared to the standard.

12

Figure 2. Headroom map of US counties using

preliminary 2021-2023 annual PM2.5 design values

(µg/m3).

Red counties in Figure 2 represent counties that

currently exceed or are interpolated to exceed the new

9.0 µg/m3 standard. Orange counties represent areas

where the headroom falls within 1–3 µg/m3 of the 9.0

µg/m3 standard and identify areas where facility

modifications or plans for new facilities may need to be

given significant consideration. Counties in green have

headroom calculations greater than 3 µg/m3 and are

likely in less jeopardy than orange-highlighted counties

for sources considering new builds or plant

modifications.

The Clean Air Act Prevention of Significant

Deterioration program applies to new major sources or

major modifications at existing sources for pollutants

where the area the source is located is in attainment

or unclassifiable with the NAAQS. It requires

installation of Best Available Control Technology, air

13

quality analysis, additional impacts analysis, and public

involvement.

EPA,

Prevention

of

Significant

Deterioration Basic Information (Dec. 15, 2025).

https://www.epa.gov/nsr/prevention-significantdeterioration-basic-information.

These

technical

examples

of

costly

ramifications of the Final Rule that was hastily

promulgated show the unjustified costs it imposes.

III.

The PM2.5 NAAQS At 9.0 µg/m3 Is Not

Attainable Nor Feasible For Much Of

The Nation.

The reduction in the PM2.5 NAAQS will lower

the compliance threshold in situations where air

quality dispersion modeling is used to document

compliance with the standard, such as new air permit

applications. However, even with all known, costeffective control technologies expended in EPA’s

regulatory impact analysis, emission reductions from

existing sources will not be enough to reach levels of

attainment at the lower end of the proposed range for

the PM2.5 NAAQS. See Final RIA at 12, 168. The Final

Rule’s reliance on this flawed data and modeling

clearly demonstrate that it was not attainable nor

feasible for much of the nation as required by the Clean

Air Act.

14

A. There Are Significant Issues With The

Updated Modeling Platform Used To Project

Attainment For 9.0 µg/m3 Annual Primary

PM2.5 Standard.

As a further illustration of deficiencies in the

Final Rule, relating to feasibility and attainment the

administrative record informs the proposed rule was

based on a 2016 emissions modeling platform with

projections to 2032 to support air quality modeling

EPA, Regulatory Impact Analysis for the Proposed

Reconsideration of the National Ambient Air Quality

Standards for Particulate Matter (Dec. 2022)

https://www.epa.gov/system/files/documents/202301/naaqs-pm_riaproposed_2022-12.pdf

(“Proposed

NAAQS RIA”). In the Final Rule, however, a 2018

platform was used to support the Rule. See Final RIA

at 101. The 2018 platform includes multiple changes

in both the base year and future year data which has

impacted

projected

nonattainment

and

implementation of the PM2.5 NAAQS and EPA’s

related assessment of the impact of the change in the

NAAQS.

The table below presents projected 2032 state

anthropogenic PM2.5 emission differences calculated

from EPA’s modeling from the proposed rule 2016

platform and the final rule 2018 platform. See United

States Environmental Protection Agency, Proposed

Rule

2016

Modeling

Platform

https://www.epa.gov/air-emissions-modeling/2016v3platform (“Proposed Rule Platform”); See also, United

States Environmental Protection Agency Final Rule

2018 Modeling Platform https://www.epa.gov/airemissions-modeling/2018v2-emissions-modelingplatform (“Final Rule Platform”).

15

Figure 3. Top 5 state anthropogenic total annual

2032 PM2.5 emission increases and decreases (%)

between proposed and final modeling platforms.

Any one of these state level emission changes

would almost certainly impact on air quality modeling

that would change designations between attainment

and nonattainment without justification. The changes

to

the

proposed

modeled

concentrations,

nonattainment

designations,

and

required

incremental emission reductions are significant

factors that are inconsistent with the thorough review

requirements of the Clean Air Act. Furthermore, major

inconsistencies have been identified in state-to-state

reporting of emission categories of PM2.5 for application

to the modeling platforms. As an example, EPA’s 2032

final reconsideration emissions platform illustrates the

inconsistency in the reporting of unpaved road dust

emissions by the states. See Final Rule Platform. Figure

4 below shows this inconsistency in modeled emissions

for this category noting that Missouri has the largest

reported unpaved road dust PM2.5 emissions in the

continental United Staes (106,858 tpy) (more than 72%

greater than Texas), while Indiana has zero reported

16

unpaved road dust PM2.5 emissions in this same

platform.

Figure 4. 2032 annual PM2.5 emissions for the

unpaved road dust category.

EPA’s reliance on air quality modeling data

based on these defects illustrates the fact the Final

Rule compels vacatur.

As was pointed out by this Court in its granting

of an emergency stay of EPA’s Good Neighbor

interstate air transport plan, the failure of EPA to offer

a reasoned response to concerns about the use of air

quality modeling would likely entitle applicants to

reversal of EPA’s rule. Ohio v EPA, 603 U.S. 279

(2024).

17

B. EPA’s PM2.5 NAAQS Revision Fails To

Consider The Impact Of Its Data

Adjustments

To

The

Monitoring

Requirement Revisions Finalized In Its

PM2.5 NAAQS Reconsideration.

An additional factor evidencing the challenges

to feasibility and attainability of the Final Rule is the

failure to have applied the agency’s approved

modification of the Federal Equivalent Method

designation for the Teledyne Advanced Pollution

Instrumentation Model T640 PM2.5 mass monitor

including the 640X option to all of the concentration

data for PM2.5 from the T640 and T640X monitors in

the EPA's Air Quality System. 89 Fed. Reg. 42,874

(May 16, 2024). EPA stated that updated data would

be available in Air Quality System by May 13, 2024,

and recommended that air agencies review the updated

data by May 28, 2024. Id.

There were more than 400 of the Teledyne T640

and 640X monitors in service as of 2023. That number

of monitors clearly has an impact on PM2.5

nonattainment designations.

The data adjustments, while laudable, occurred

after EPA promulgated the revised PM2.5 NAAQS, and

EPA did not account for the impact of the biased data

in establishing the revised PM2.5 NAAQS. Indeed, in its

May 13, 2024, response to comments on the proposed

data adjustment EPA conceded that “[o]ne commenter

asserted that this comprehensive Network Data

Alignment is improper because the EPA failed to

consider the potential health effects associated with

the action” and added that “[t]his comment is beyond

the scope of this action, as any health impacts related

to PM2.5 monitoring and NAAQS attainment are

18

addressed through the 2024 Final PM2.5 NAAQS rule

and will likely be addressed by any future NAAQSsetting actions.” EPA, Summary of and Responses to

Public Comments on the EPA’s Plan to Update PM2.5

Data from T640/T640X PM Mass Monitors, May 13,

2024. https://www.regulations.gov/document/EPA-HQOAR-2023-0642-0032.

Because the bias of historical data for the many

Teledyne PM2.5 monitors in the monitoring network has

been confirmed by EPA, and especially because that

bias is likely to be more pronounced for wildfire smoke

events, the data may have resulted in both inaccurate

calculation of PM2.5 design values and erroneous

designation of PM2.5 nonattainment areas. EPA’s failure

to assess the impact of the biased data on PM

nonattainment as part of its PM2.5 NAAQS

reconsideration is a demonstrable fact that the agency

failed to consider all relevant facts as prescribed by the

Court in Michigan; accordingly, this Final Rule is not

based on reasoned decision-making.

IV. EPA’s Failure to Consider the Disparate

Health Effects Of Speciated PM2.5 Particles

Demonstrates Lack of Thorough Review.

During the review of the PM2.5 NAAQS (EPA-HQOAR-2015-0072) that resulted in promulgation of the

revised PM2.5 NAAQS to 9 µ/m3, numerous commenters

advised EPA that all PM2.5 is not alike and urged EPA to

account for the differences in speciated PM2.5 in setting a

revised standard. Indeed, as long ago as 2016, the Texas

Commission on Environmental Quality (TCEQ)

submitted comments to EPA stating that “[t]he EPA

should place significant focus on the impact of individual

PM components on measured health endpoints,” adding

19

that “[i]t is generally acknowledged that not all species

of PM are equally toxic, with metals being generally

more toxic (reviewed in Chen and Lippman 2009) and

nitrates generally less so (reviewed in Schlesinger

2007).” EPA-HQ-OAR-2015-0072-0008. In 2017, the

Texas Public Policy Foundation submitted a comment

stating that “[d]ata on speciated PM2.5 are necessary to

test hypotheses on whether different PM 2.5 components

have different potencies for causing an increase in

different health effects.” EPA-HQ-OAR-2015-00721812.

More recently, in 2023, The Nature Conservancy

recommended that EPA “take advantage of speciated

particulate monitoring technology to provide valuable

information about the composition, and ultimately the

sources, of PM2.5 pollution.” EPA-HQ-OAR-2015-00722219.

EPA has thus known for over a decade about

scientific concerns regarding the disparate health effects

of various species of particulate matter, even if all is

sized at 2.5 microns or less in aerodynamic diameter the PM2.5 standard size. This exact observation has been

substantiated in various technical assessment

documents prepared to justify regulatory actions. EPA

has nonetheless failed to collect data or begin to consider

these disparate health effects, a fatal flaw in its revised

PM2.5 NAAQS.

In its 2024 Responses to Significant Comments

on the 2023 Proposed Rule for the Reconsideration of

the National Ambient Air Quality Standards for

Particulate Matter (EPA-HQ-OAR-2015-0072-6010),

EPA evidently did not consider any of these and other

comments as sufficiently significant to respond. There

is no mention of the issue of disparate health effects of

the various speciated PM2.5 constituents in the

20

response to “significant” comments. EPA has

consistently failed to begin to consider these disparate

health effects, an onerous legal flaw in its revised

PM2.5 NAAQS.

CONCLUSION

For the reasons set forth above, as well as the

reasons set forth in the petitions, the Court should

grant the petitions and undertake review of the merit

of the Final Rule.

Respectfully submitted,

KATHY G. BECKETT

Counsel of Record

DAVID M. FLANNERY

EDWARD L. KROPP

STEPTOE & JOHNSON PLLC

Post Office Box 1588

Charleston, WV 25326

(304) 353-8000

Kathy.Beckett@Steptoe-Johnson.com

Counsel for Amicus Curiae Midwest Ozone Group