U.S. GOVERNMENT PUBLISHING OFFICE

30–876PDF WASHINGTON : 2018

STATE PERSPECTIVES ON 

REGULATING BACKGROUND OZONE 

HEARING 

BEFORE THE

SUBCOMMITTEE ON ENVIRONMENT 

COMMITTEE ON SCIENCE, SPACE, AND 

TECHNOLOGY 

HOUSE OF REPRESENTATIVES 

ONE HUNDRED FIFTEENTH CONGRESS 

SECOND SESSION 

JUNE 21, 2018 

Serial No. 115–65 

Printed for the use of the Committee on Science, Space, and Technology 

( 

Available via the World Wide Web: http://science.house.gov 
(II) 

COMMITTEE ON SCIENCE, SPACE, AND TECHNOLOGY 

HON. LAMAR S. SMITH, Texas, Chair 

FRANK D. LUCAS, Oklahoma 

DANA ROHRABACHER, California 

MO BROOKS, Alabama 

RANDY HULTGREN, Illinois 

BILL POSEY, Florida 

THOMAS MASSIE, Kentucky 

RANDY K. WEBER, Texas 

STEPHEN KNIGHT, California 

BRIAN BABIN, Texas 

BARBARA COMSTOCK, Virginia 

BARRY LOUDERMILK, Georgia 

RALPH LEE ABRAHAM, Louisiana 

GARY PALMER, Alabama 

DANIEL WEBSTER, Florida 

JIM BANKS, Indiana 

ANDY BIGGS, Arizona 

ROGER W. MARSHALL, Kansas 

NEAL P. DUNN, Florida 

CLAY HIGGINS, Louisiana 

RALPH NORMAN, South Carolina 

DEBBIE LESKO, Arizona 

EDDIE BERNICE JOHNSON, Texas 

ZOE LOFGREN, California 

DANIEL LIPINSKI, Illinois 

SUZANNE BONAMICI, Oregon 

AMI BERA, California 

ELIZABETH H. ESTY, Connecticut 

MARC A. VEASEY, Texas 

DONALD S. BEYER, JR., Virginia 

JACKY ROSEN, Nevada 

CONOR LAMB, Pennsylvania 

JERRY MCNERNEY, California 

ED PERLMUTTER, Colorado 

PAUL TONKO, New York 

BILL FOSTER, Illinois 

MARK TAKANO, California 

COLLEEN HANABUSA, Hawaii 

CHARLIE CRIST, Florida 

SUBCOMMITTEE ON ENVIRONMENT

ANDY BIGGS, ARIZONA, Chair 

DANA ROHRABACHER, California 

BILL POSEY, Florida 

MO BROOKS, Alabama 

RANDY K. WEBER, Texas 

BRIAN BABIN, Texas 

GARY PALMER, Alabama 

CLAY HIGGINS, Louisiana 

RALPH NORMAN, South Carolina, Vice 

Chair 

DEBBIE LESKO, Arizona 

LAMAR S. SMITH, Texas 

SUZANNE BONAMICI, Oregon 

COLLEEN HANABUSA, Hawaii 

CHARLIE CRIST, Florida 

CONOR LAMB, Pennsylvania 

EDDIE BERNICE JOHNSON, Texas 
(III) 

C O N T E N T S 

June 21, 2018 

Page 

Witness List ............................................................................................................. 2 

Hearing Charter ...................................................................................................... 3 

Opening Statements 

Statement by Representative Andy Biggs, Chairman, Subcommittee on Environment, Committee on Science, Space, and Technology, U.S. House of 

Representatives .................................................................................................... 4 

Written Statement ............................................................................................ 6 

Statement by Representative Suzanne Bonamici, Ranking Member, Subcommittee on Environment, Committee on Science, Space, and Technology, 

U.S. House of Representatives ............................................................................ 8 

Written Statement ............................................................................................ 10 

Statement by Representative Lamar S. Smith, Chairman, Committee on 

Science, Space, and Technology, U.S. House of Representatives ..................... 12 

Written Statement ............................................................................................ 14 

Statement by Representative Eddie Bernice Johnson, Ranking Member, Committee on Science, Space, and Technology, U.S. House of Representatives .... 16 

Written Statement ............................................................................................ 17 

Witnesses: 

Ms. Diane Rath, Executive Director, Alamo Area Council of Governments 

Oral Statement ................................................................................................. 19 

Written Statement ............................................................................................ 21 

Mr. Timothy Franquist, Air Quality Division Director, Arizona Department 

of Environmental Quality 

Oral Statement ................................................................................................. 29 

Written Statement ............................................................................................ 31 

Dr. Elena Craft, Senior Health Scientist, Environmental Defense Fund 

Oral Statement ................................................................................................. 90 

Written Statement ............................................................................................ 92 

Mr. Gregory Stella, Senior Scientist, Alpine Geophysics 

Oral Statement ................................................................................................. 107 

Written Statement ............................................................................................ 109 

Discussion ................................................................................................................. 116

Appendix I: Additional Material for the Record 

Letter submitted by Representative Lamar S. Smith, Chairman, Committee 

on Science, Space, and Technology, U.S. House of Representatives ................ 136 

Documents submitted by Representative Suzanne Bonamici, Ranking Member, Subcommittee on Environment, Committee on Science, Space, and 

Technology, U.S. House of Representatives ....................................................... 144 

Documents submitted by Representative Donald S. Beyer, Jr., Committee 

on Science, Space, and Technology, U.S. House of Representatives ................ 148 

(1) 

STATE PERSPECTIVES ON REGULATING 

BACKGROUND OZONE 

THURSDAY, JUNE 21, 2018 

HOUSE OF REPRESENTATIVES, 

SUBCOMMITTEE ON ENVIRONMENT

COMMITTEE ON SCIENCE, SPACE, AND TECHNOLOGY, 

Washington, D.C. 

The Subcommittee met, pursuant to call, at 10:04 a.m., in Room 

2318 of the Rayburn House Office Building, Hon. Andy Biggs 

[Chairman of the Subcommittee] presiding. 
2 

LAMAR S SMITH, Te~as 

CHA!i'lMAN 

Q:ongrcss of the llnitcd ~teres 

i'lousc of 'Rcprcsrntatiocs COMMITTEE ON SCIENCE, SPACE, AND TECHNOLOGY 

2321 RAV8URN HOUSE OFFICE BUILDING 

WASHINGTON, DC 20515--6301 

(202) 225-6371 

wv.rwscl8ncehouse.gov 

Subcommittee on Environment 

State Perspectives on Regulating Background Ozone 

Thursday, June 21, 2018 

!O:OOa.m. 

2318 Rayburn House Office Building 

Witnesses 

EDDIE BERNICE JOHNSON, T~<xa~ 

RANKING MEMBER 

Ms. Diane Rath, Executive Director, Alamo Area Council of Governments 

Mr. Timothy Franquist, Air Quality Division Director, Arizona Department of 

Environmental Quality 

Dr. Elena Craft, Senior Health Scientist, Environmental Defense Fund 

Mr. Gregory Stella, Senior Scientist, Alpine Geophysics, LLC. 
3 

U.S. HOUSE OF REPRESENTATIVES 

COMMITTEE ON SCIENCE, SPACE, AND TECHNOLOGY 

HEARING CHARTER 

Thursday, June 21, 2018 

TO: Members, Subcommittee on Environment 

FROM: Majority Staff, Committee on Science, Space, and Technology 

SUBJECT: Subcommittee hearing: "State Perspectives on Regulating Background Ozone" 

The Subcommittee on Environment will hold a hearing titled State Perspectives on 

Regulating Background Ozone on Thursday, June 21, 2018, at I 0:00 a.m. in Room 2318 of the 

Rayburn House Office Building. 

Hearing Purpose: 

The purpose of this hearing is to examine the ozone National Ambient Air Quality 

Standards (NAAQS). This hearing will also explore the policy and available remedies to address 

natural and international background ozone under the Clean Air Act. 

Witness List 

• Ms. Diane Rath, Executive Director, Alamo Area Council of Governments 

• Mr. Timothy Franquist, Air Quality Division Director, Arizona Department of 

Environmental Quality 

• Dr. Elena Craft, Senior Health Scientist, Environmental Defense Fund 

• Mr. Gregory Stella, Senior Scientist, Alpine Geophysics 

Staff Contact 

For questions related to the hearing, please contact Majority Staff at 202-225-6371. 
4 

Chairman BIGGS. The Subcommittee on Environment will come 

to order. Without objection, the Chair is authorized to declare recess of the Subcommittee at any time. 

Welcome to today’s hearing entitled ‘‘State Perspectives on Regulating Background Ozone.’’ Before we get started, I want to take a 

moment to recognize the new Vice Chairman of the Subcommittee, 

Mr. Norman from South Carolina. I look forward to continuing our 

work together and the success of the Environment Committee. 

I now recognize myself for five minutes for an opening statement. 

In 2015, the Obama EPA lowered the National Ambient Air 

Quality Standard (NAAQS) from 75 parts per billion to 70 parts 

per billion. Meeting this new, unreasonable standard has placed an 

excessive economic burden on States across the country, and especially those in the Southwest. In my own State of Arizona, naturally-occurring background ozone, over which we have virtually no 

control, has created a compliance nightmare. 

The solution to this problem is simple: the EPA should take local 

geographic factors into account when determining ozone standards. 

Simply slapping a ‘‘nonattainment’’ designation on areas where 

ozone emissions are not even originating is both unfair and devastating to business in the state. Background ozone can come from 

both domestic and international sources. For instance, a large 

amount of Arizona emissions originate in Mexico. However, the 

way the NAAQS are set, these emissions from outside the country 

are used against U.S. states. 

The tragic result is that the Clean Air Act ends up burdening the 

very Americans it seeks to help—more often than not, hard-working people living in rural areas. Cutting emissions has become synonymous with cutting jobs. 

Instead of enforcing unreasonable mandates, the states and EPA 

should instead work together to determine the amount of manmade emissions versus natural and international emissions in any 

given area. It makes absolutely no sense to force an area within 

the United States to try to compensate for emissions caused by 

other countries. 

At first glance, Section 179B of the Clean Air Act seems to offer 

relief from emissions from international sources. However, when 

put into practice, it does not go far enough. A successful 179B demonstration does not allow an area to avoid a ‘‘nonattainment’’ designation; it just relieves it of some potential sanctions. 

We cannot continue to punish states for emissions it cannot control. A nonattainment designation in turn triggers a nonattainment 

New Source Review, which then applies to all new major sources 

or major modifications to existing sources of pollutants. So, if a new 

business wants to open up or an old business wants to make certain changes, it has to go through the NSR process. 

One of the requirements in this process is for a company to offset 

emissions. But in agricultural communities, where big business is 

the exception not the rule, offsets are almost impossible. There are 

simply not enough businesses to offset against. This is why businesses would be reluctant to set up shop in a rural area that is in 

nonattainment, and I don’t blame them. In a situation where sanctions are costly and offsets are impossible, businesses are not given 
5 

much of a choice. Job opportunities disappear and environmental 

regulations end up institutionalizing poverty. 

We need to find a better system, and I look forward to this hearing as a way to explore these issues and foster a true discussion 

on the impacts of background ozone. 

[The prepared statement of Chairman Biggs follows:] 
6 

COMMITTEE ON 

SCIENCE, SPACE, & TECHNOLOGY lamar Smith, Chairman 

For Immediate Release 

June 21, 2018 

Media Contact: Bridget Dunn 

(202) 225-6371 

Statement by Chairman Andy Biggs (R-Ariz.) 

State Perspectives on Regulating Background Ozone 

Chairman Biggs: In 2015, the Obama EPA lowered the National Ambient Air Quality Standard 

(NAAQS) from 75 parts per billion to 70 parts per billion. Meeting this new, unreasonable 

standard has placed an excessive economic burden on states across the country, and 

especially those in the Southwest. In my own state of Arizona, naturally-occurring 

background ozone-over which we have virtually no control-has created a compliance 

nightmare. 

The solution to this problem is simple: the EPA should take local geographic factors into 

account when determining ozone standards. Simply slapping a "nonattainment" 

designation on areas where ozone emissions are not even originating is both unfair and 

devastating to business in the state. Background ozone can come from both domestic and 

international sources. For instance. a large amount of Arizona emissions originate in Mexico. 

However. the way the NAAQS are set, these emissions from outside the country are used 

against U.S. states. 

The tragic result is that the Clean Air Act ends up burdening the very Americans it seeks to 

help-more often than not, hard-working people living in rural areas. Cutting emissions has 

become synonymous with cutting jobs. 

Instead of enforcing unreasonable mandates, the states and EPA should instead work 

together to determine the amount of man-made emissions versus natural and international 

emissions in any given area. It makes absolutely no sense to force an area within the U.S. to 

try to compensate for emissions caused by other countries. 

At first glance. Section 179B of the Clean Air Act seems to offer relief from emissions from 

international sources. However, when put into practice, it does not go far enough. A 

successful 179B demonstration does not allow an area to avoid a "nonaltainment" 

designation; it just relieves it of some potential sanctions. 

We cannot continue to punish states for emissions it cannot control. A nonattainment 

designation in turn triggers a nonattainment New Source Review (NSR), which then applies to 

all new major sources or major modifications to existing sources of pollutants. So, if a new 

business wants to open up or an old business wants to make certain changes. it has to go 

through the NSR process. 
7 

One of the requirements in this process is for a company to offset emissions. But in agricultural 

communities, where big business is the exception not the rule, offsets are almost impossible. 

There are simply not enough businesses to offset against. 

This is why businesses would be reluctant to set up shop in a rural area that is in 

nonattainment-and I don't blame them. In a situation where sanctions are costly and 

offsets are impossible, businesses aren't given much of a choice. Job opportunities 

disappear and environmental regulations end up institutionalizing poverty. 

We need to find a better system, and I look forward to this hearing as a way to explore these 

issues and foster a true discussion on the impacts of background ozone. 

### 
8 

Chairman BIGGS. I now recognize the Ranking Member of the 

Subcommittee, the gentlewoman from Oregon, Ms. Bonamici, for an 

opening statement. 

Ms. BONAMICI. Thank you, Mr. Chairman. 

The Clean Air Act is one of the most successful pieces of public 

health legislation enacted by Congress. According to the EPA, the 

protections helped avoid more than 200,000 premature deaths in 

its first 20 years alone. A clean environment is essential to a high 

quality of life for every American. It is important to consider the 

health effects of weakened air standards, particularly for children, 

the elderly and those suffering from asthma. 

The National Ambient Air Quality Standards, or NAAQS, were 

established under the Clean Air Act to regulate criteria pollutants 

that have significant negative effects on human health. Congress 

made sure that public health was the driving factor in setting the 

NAAQS by requiring the standards to be based on exclusively on 

scientific, health-based evidence. 

Since 2008, The Environmental Protection Agency’s Clean Air 

Scientific Advisory Committee has recommended setting the ozone 

standard between 60 and 70 parts per billion. In 2015, the ozone 

NAAQS were strengthened to 70 parts per billion. Public health 

groups were concerned that the new level was still not as protective as it could have been, but acknowledged the positive health 

outcomes the new standard would have for all Americans. 

Some states and localities argue that meeting the 2015 ozone 

NAAQS levels is impossible because of background or naturally occurring ozone levels, but that is simply not true. The EPA determined that background ozone levels remain relatively constant, 

and contribute only fractionally to ozone concentrations above the 

70 parts per billion level on high ozone days. The EPA also recently 

revised their Exceptional Events Rule and Guidance to more clearly define the scope of the rule to help states and localities identify 

air quality monitoring data that may be affected by exceptional 

events. 

I would like to thank our witnesses for being here today. I’m glad 

to see Dr. Elena Craft back at the witness table to provide us with 

a scientific perspective not only on issues related to ozone, but also 

to discuss how the anti-science actions this Administration has 

taken at the EPA will undermine public health protections if left 

unchallenged. 

I would also like to draw attention to the fact that it has been 

one year and 4 months since Scott Pruitt was confirmed as the 

EPA Administrator. In that time, Democratic members of this 

Committee have sent multiple letters to Chairman Smith requesting the Administrator’s presence at the witness table. The Ranking 

Member of the Full Committee and I have both requested, on the 

record, during Committee hearings that Administrator Pruitt be 

asked to testify in front of the Science Committee, only to be told 

that we could invite him ourselves. So we did. In fact, I invited Administrator Pruitt to participate in today’s hearing as the Minority 

witness, but he rejected our request. 

This Committee is doing a disservice to the American people by 

not having the EPA Administrator testify to explain his antiscience agenda and explain the actions he’s taking that will under-
9 

mine public health and the environment. This is especially egregious considering that this Committee has jurisdiction over the 

EPA, and Administrator Pruitt has found the time to testify in 

front of other congressional committees multiple times. 

The EPA Administrator and Committee Chairman are touting 

the need for more transparency in science at the EPA. It seems 

that Administrator Pruitt’s testimony in front of this Committee 

would be a key part of fulfilling that goal. It is our job to monitor 

Agency activities and to make sure they are consistent with congressional intent. We should not abdicate our responsibility to hold 

this Administration accountable. 

So I sincerely hope this Committee will fulfill its duty to conduct 

congressional oversight of the EPA’s science programs to make sure 

the Agency meets its mandate to protect public health and the environment. 

And Mr. Chairman, I have a letter from nine public health, medical, and nursing organizations that support the full implementation and enforcement of the ozone NAAQS under the Clean Air Act. 

This letter also lays out concerns with the May 2018 memo on updating the NAAQS review process written by EPA Administrator 

Scott Pruitt that is inconsistent with the statutory requirements in 

the Clean Air Act. This letter highlights the importance of maintaining the NAAQS as a health-based standard built on scientific 

evidence and not allowing additional considerations such as cost or 

technically feasibility—technical feasibility to play a role in setting 

the standards. I ask unanimous consent that this letter be entered 

into the record. 

Chairman BIGGS. Without objection. 

[The information appears in Appendix I] 

Ms. BONAMICI. Thank you, and Mr. Chairman, I also have a poll 

conducted in April of 2018 by the American Lung Association that 

found that 75 percent of voters support the enforcement of the 2015 

Ozone Standard. This included a plurality of Republicans. Mr. 

Chairman, I would like to add the results of the American Lung 

Association’s poll into the record. 

Chairman BIGGS. Without objection. 

[The information appears in Appendix I] 

Ms. BONAMICI. Thank you, Mr. Chairman, and I yield back. 

[The prepared statement of Ms. Bonamici follows:] 
10 

OPENING STATEMENT 

Ranking Member Suzanne Bonamici (D-OR) 

of the Subcommittee on Environment 

House Committee on Science, Space, and Technology 

Subcommittee on Environment 

"State Perspectives on Regulating Background Ozone" 

June 21, 2018 

Thank you, Mr. Chairman. The Clean Air Act is one of the most successful pieces of public 

health legislation enacted by Congress. The protections helped avoid more than 200,000 

premature deaths in its first 20 years alone. A clean environment is essential to a high quality of 

life for every American. It is important to consider the health effects of weakened air standards, 

particularly for children, the elderly and those suffering from asthma. 

The National Ambient Air Quality Standards, or NAAQS, were established under the Clean Air 

Act to regulate criteria pollutants that have significant negative effects on human health. 

Congress made sure that public health was the driving factor in setting the NAAQS by requiring 

the standards to be based on exclusively on scientific, health-based evidence. 

Since 2008, The Environmental Protection Agency's Clean Air Scientific Advisory Committee 

has recommended setting the ozone standard between 60 and 70 parts per billion. In 2015, the 

ozone NAAQS were strengthened to 70 parts per billion. Public health groups were concerned 

that the new level was not as protective as it could have been, but acknowledged the positive 

health outcomes the new standard would have for all Americans. 

Some states and localities argue that meeting the 2015 ozone NAAQS levels is impossible 

because of background or naturally occurring ozone levels, but that is simply not true. The EPA 

determined that background ozone levels remain relatively constant, and contribute only 

fractionally to ozone concentrations above the 70 parts per billion level on high ozone days. The 

EPA also recently revised their Exceptional Events Rule and Guidance to more clearly define the 

scope of the rule to help states and localities identify air quality monitoring data that may be 

affected by exceptional events. 

I would like to thank our witnesses for being here today. I am glad to see Dr. Elena Craft back at 

the witness table to provide us with a scientific perspective not only on issues related to ozone, 

but also to discuss how the anti-science actions this Administration has taken at the EPA will 

undermine public health protections if left unchallenged. 

I would also like to draw attention to the fact that it has been one year and four months since 

Scott Pruitt was confirmed as the EPA Administrator. In that time, the Democratic members of 

this Committee have sent multiple letters to Chairman Smith requesting the Administrator's 

presence at the witness table. The Ranking Member of the full Committee and I have both 

requested, on the record, during Committee hearings that Administrator Pruitt be asked to testify 

in front of the Science Committee, only to be told that we could invite him ourselves. We did; in 
11 

fact I invited Administrator Pruitt to participate in today's hearing as the Minority witness, but he 

rejected our request. 

This Committee is doing a disservice to the American people by not having the EPA 

Administrator testify to explain his anti-science agenda and explain the actions he is taking that 

will undermine public health and the environment. This is especially egregious considering that 

this Committee has jurisdiction over the EPA, and that Administrator Pruitt has found the time to 

testify in front of other congressional committees multiple times. 

The EPA Administrator and Committee Chairman are touting the need for more transparency in 

science at the EPA. It seems that Administrator Pruitt's testimony in front of this Committee 

would be a key part of fulfilling that goal. It is our job to monitor Agency activities to make sure 

they are consistent with congressional intent, and we should not abdicate our responsibility to 

hold this Administration accountable. 

I sincerely hope this Committee decides to fulfill its duty to conduct congressional oversight of 

the EPA's science programs to make sure the Agency meets its mandate to protect public health 

and the environment. Thank you, Mr. Chairman, and with that I yield back. 
12 

Chairman BIGGS. The gentlelady yields back. 

I now recognize the Chairman of the Full Committee, Chairman 

Smith, for his opening statement. 

Chairman SMITH. Thank you, Mr. Chairman, and thanks to our 

witnesses for being here today as well. And before we begin, I’d like 

to congratulate the gentleman from South Carolina to my right, 

Mr. Norman, for being the new Vice Chairman of the Subcommittee. We look forward to his contributions to the Committee. 

We’ve already seen examples of that in the last few months. 

The Science Committee—I’m sorry I’m so hoarse today. It’s better 

than having lost my voice, which I did yesterday, and Suzanne, you 

can’t comment on my losing my voice and wishing that were the 

case today. 

Ms. BONAMICI. Duly noted, Mr. Chairman. 

Chairman SMITH. The Science Committee has held a number of 

hearings on the regulatory overreach of the previous Administration’s Environmental Protection Agency. Today’s hearing is a timely discussion on the National Ambient Air Quality Standards, or 

NAAQS. 

The air in the U.S. is cleaner than it has ever been before. Yet 

in 2015 the previous Administration tightened the NAAQS for 

ground-level ozone. 

The fastest way to hurt our local economy is to implement far 

reaching regulations that stunt business growth and development. 

The 2015 NAAQS often places heavy burdens on the American people, with few actual benefits. 

Ensuring we have clean air and water, now and in the future, 

is important and should be a priority for everyone. However, regulations that stifle business and innovation, while doing little to actually meet these goals, are counterproductive. 

Instead of using an unachievable, one-size-fits-all approach, the 

EPA should collaborate with the States and come up with plans 

that actually work. Background ozone includes both natural and 

international ozone. Natural ozone comes from many sources including wildfires, lightning and vegetation. International ozone refers to emissions coming from other countries like China and Mexico. 

In some areas of the country, even background ozone levels exceed 70 parts per billion. In these areas, no matter how much a 

State controls its own emissions, it will never be able to comply 

with the 2015 NAAQS level. 

We simply cannot beat mother nature and we cannot force other 

countries to stop their emissions. Geologic areas should not be held 

accountable for emissions they cannot control. 

Many areas that receive a nonattainment designation suffer economically. This designation discourages businesses from moving 

into the State because they would have to deal with permitting and 

compliance obligations. This in turn limits employment opportunities for hardworking Americans living in our rural communities. 

Let me say, it’s good to have a personal friend from San Antonio, 

Diane Rath, who happens to live in my district, and is here to comment on background ozone issues facing Texas. San Antonio, for example, is directly and adversely affected by the international ozone 

from Mexico. 
13 

Less than a quarter of ozone emissions detected in San Antonio 

actually originated in the city. Yet to comply with the NAAQS, San 

Antonio must implement a burdensome regulatory agenda that adversely affects businesses and citizens alike. 

Being a good steward of the environment and promoting a 

healthy economy are not mutually exclusive. Hard working Americans are hit the hardest by these expensive regulations. Regulatory 

overreach costs billions of dollars, kills jobs and hurts the economy. 

For example, expensive permitting regulations discourage employers from establishing businesses and creating jobs. 

Because states have no control over international and natural 

emissions, even a state’s greatest efforts to reduce emissions often 

fall short of the benefits envisioned by the Clean Air Act. 

I remain hopeful that the EPA will review the current NAAQS 

standards and evaluate the science and process behind setting future NAAQS. Recently, Administrator Pruitt laid out five principles 

that will be implemented in future NAAQS reviews. This ‘‘back-tobasics’’ process will ensure that sound science is the foundation of 

the NAAQS standards and that all relevant data is considered in 

implementation, including naturally occurring and international 

ozone. 

Thank you, Mr. Chairman, and I’ll yield back the balance of my 

time. 

[The prepared statement of Chairman Smith follows:] 
14 

COMMITTEE ON 

SCIENCE, SPACE, & TECHNOLOGY Lamar Smith, Chairman 

For Immediate Release 

June 21.2018 

Media Contact: Bridget Dunn 

(202) 225-6371 

Statement by Chairman Lamar Smith (R-Texas) 

State Perspectives on Regulating Background Ozone 

Chairman Smith: Thank you, Mr. Chairman, and thanks to our witnesses for being here today. 

Before we begin, I'd like to congratulate the gentleman from South Carolina, Mr. Norman, 

who is the new vice chairman of the Environment Subcommittee. We look forward to his 

contributions to the subcommittee. 

The Science Committee has held a number of hearings on the regulatory overreach of the 

previous administration's Environmental Protection Agency (EPA). Today's hearing is a timely 

discussion on the National Ambient Air Quality Standards (NAAQS). 

The air in the U.S. is cleaner than it has ever been. Yet in 2015 the previous administration 

tightened the NAAQS for ground-level ozone. 

The fastest way to hurt our local economy is to implement far reaching regulations that stunt 

business growth and development. The 2015 NAAQS often places heavy burdens on the 

American people, with few actual benefits. 

Ensuring we have clean air and water. now and in the future, is important and should be a 

priority for everyone. However. regulations that stifle business and innovation. while doing 

little to actually meet these goals. are counterproductive. 

Instead of using an unachievable, one-size-fits-all approach, EPA should collaborate with the 

states and come up with plans that actually work. Background ozone includes both natural 

and international ozone. Natural ozone comes from rnany sources including wildfires. 

lightning and vegetation. International ozone refers to emissions coming from other countries 

like China and Mexico. 

In some areas of the country, even background ozone levels exceed 70 parts per billion. In 

these areas, no matter how much a state controls its own emissions it will never be able to 

comply with the 2015 NAAQS level. 

We cannot beat mother nature and we cannot force other countries to stop their emissions. 

Geographic areas should not be held accountable for emissions they can't control. 

Many areas that receive a non-attainment designation suffer economically. This designation 

discourages businesses from moving into the state because they would have to deal with 

permitting and compliance obligations. This in turn limits employment opportunities for 

hardworking Americans living in our rural communities. 
15 

It's good to have Diane Roth from my district in San Antonio here to comment on 

background ozone issues facing Texas. San Antonio, for example, is directly and adversely 

affected by the international ozone frorn Mexico. 

Less than a quarter of ozone emissions detected in San Antonio actually originated in that 

city. Yet to comply with the NAAQS, San Antonio must implement a burdensome regulatory 

agenda that adversely affects businesses and citizens alike. 

Being a good steward of the environment and promoting a healthy economy are not 

mutually exclusive. Hard working Americans are hit the hardest by these expensive 

regulations. Regulatory overreach costs billions of dollars, kills jobs and hurts the economy. 

For example, expensive permitting regulations discourage employers from establishing 

businesses and creating jobs. 

Because states have no control over international and natural emissions. even a state's 

greatest efforts to reduce emissions often fall short of the benefits envisioned by the Clean Air 

Act. 

I remain hopeful that the EPA will review the current NAAQS standards and evaluate the 

science and process behind setting future NAAQS. Recently, Administrator Pruitt laid out five 

principles that will be implemented in future NAAQS reviews. 

This "back-to-basics" process will ensure that sound science is the foundation of the NAAQS 

standards and that all relevant data is considered in implementation. including naturally 

occurring and international ozone. 

### 
16 

Mr. BIGGS. The gentleman yields, and I now recognize the Ranking Member of the Full Committee, Ms. Johnson, for an opening 

statement. 

Ms. JOHNSON. Thank you very much, Mr. Biggs, and I want to 

thank all of our witnesses for being here to discuss their perspectives on air pollution regulations. 

For the past several years, whenever the Majority has held a 

hearing on air pollution there has been one common thread. Virtually every hearing has highlighted one or more excuses as to why 

air pollution shouldn’t be regulated. Today, we will hear about another excuse: background ozone. This isn’t even a novel excuse. We 

held a hearing on this same topic just a few years ago. 

One thing the Committee never seems to address is the public 

health effects of Americans breathing in air pollution. I’m a nurse. 

I’ve done some studies. And those health effects are devastating. 

Disease, misery, and death. In addition to the severe bodily toll 

that air pollution takes on Americans, it is also—it also imposes a 

serious monetary cost. It is estimated that the EPA’s 2015 Ozone 

regulations, which were only slightly more stringent than the previous standards, would result in hundreds of thousands dollars— 

of fewer asthma attacks in children every year. They continue, 

however, to go up. That would, in turn, result in over 100,000 less 

missed school days, which, in turn, would result in significantly increased productivity for the parents of those children. And just— 

that just deals with asthma. These regulations would also reduce 

COPD, cardiovascular disease, and other negative health effects. 

The total health care savings from regulating ozone even slightly 

more stringently than before runs well into the billions of dollars 

every year. That should really come as no surprise to the Members 

of Congress. Healthcare is very expensive. Rising healthcare costs 

are one of the primary drivers of our increasing national debt. As 

we work to address these issues, I think it makes more sense to 

cut the pollution that is helping to drive those healthcare costs 

higher, rather than cutting the healthcare treatments people need 

to survive. 

I hope that the Minority witness, Dr. Craft, can help us highlight 

some of the reasons why it is so important to regulate air pollution 

in the first place. And I’m sure that she can also address the rationale being offered today by our Majority for why we shouldn’t be 

regulating pollution. 

I am from Texas, and we get plenty of cross border air pollution 

coming from our neighbors to the South. Not just Mexico, but Louisiana sits over there, too. Quite frankly, we probably also send a 

little air pollution to our neighbors in the east. Every state has its 

own unique issues related to reducing air pollution. But I don’t 

think that is an excuse to let people in Dallas, Houston or San Antonio get sick and suffer. I hope we can keep that in mind today 

as we talk about these compliance issues. I look forward to hearing 

from our witnesses, and I yield back. 

[The prepared statement of Ms. Johnson follows:] 
17 

OPENING STATEMENT 

Ranking Member Eddie Bernice Johnson (D-TX) 

House Committee on Science, Space, and Technology 

Subcommittee on Environment 

"State Perspectives on Regulating Background Ozone" 

June 21,2018 

Thank you, Chairman Biggs. I also want to thank all of our witnesses for being here today to 

discuss their perspectives on air pollution regulations. 

For the past several years, whenever the Majority has held a hearing on air pollution there has 

been one common thread. Virtually every hearing has highlighted one or more excuses as to why 

air pollution shouldn't be regulated. Today, we will hear about another excuse: background 

ozone. This isn't even a novel excuse. We held a hearing on this same topic just a few years ago. 

One thing the Committee never seems to address is the public health effects of Americans 

breathing in air pollution. And those health effects are devastating. Disease, misery, and death. In 

addition to the severe bodily toll that air pollution takes on Americans, it also imposes a serious 

monetary cost. It is estimated that the EPA's 2015 Ozone regulations, which were only slightly 

more stringent than the previous standards, would result in hundreds of thousands of fewer 

asthma attacks in children every year. That would, in tum, result in over 100,000 less missed 

school days, which, in tum, would result in significantly increased productivity for the parents of 

those children. And that just deals with asthma. These regulations would also reduce COPD, 

cardiovascular disease, and other negative health effects. 

The total health care savings from regulating ozone even slightly more stringently than before 

runs well into the billions of dollars every year. That should really come as no surprise to 

Members of Congress. Health care is very expensive. Rising health care costs are one of the 

primary drivers of our increasing national debt. As we work to address these issues, I think it 

makes more sense to cut the pollution that is helping to drive those health care costs higher, 

rather than cutting the health care treatments people need to survive. 

I hope that the Minority witness, Dr. Craft can help highlight some of the reasons why it is so 

important to regulate air pollution in the first place. And I'm sure she can also address the 

rationale being offered today by our Majority for why we shouldn't be regulating pollution. 

I'm from Texas, and we get plenty of cross border air pollution coming from our neighbors to the 

South. Quite frankly, we probably also send a little air pollution to our neighbors to the east. 

Every state has its own unique issues related to reducing air pollution. But I don't think that is an 

excuse to let people in Dallas or Houston or San Antonio get sick and suffer. I hope we can keep 

that in mind today as we talk about these compliance issues. 

I look forward to hearing from our witnesses today, and I yield back. 
18 

Chairman BIGGS. The gentlelady yields back. Thank you. 

I now recognize Chairman Smith to introduce our first witness. 

Chairman SMITH. Thank you, Mr. Chairman. I’m glad to be able 

to introduce Diane Rath, the Executive Director of the Alamo Area 

Council of Governments, which serves much of my home district 

back in Texas. 

Ms. Rath began work in public service when then-Governor 

George Bush appointed her Chair of the Texas Workforce Commission. She was then nominated by President Bush to be Assistant 

Secretary of Administration for Children and Families at the U.S. 

Department of Health and Human Services. During this time, she 

became recognized as a national leader in workforce development. 

Prior to her current position, Ms. Rath served as Senior Vice 

President at ResCare Workforce Services with oversight responsibility for operations at over 300 locations in 28 States. 

As Executive Director of AACOG, she oversees 300 employees and 11 program areas with a budget of $50 million. Ms. Rath attended Texas Christian University and graduated from the University of Texas Medical Branch at Galveston. 

We are pleased to have her here. I yield back. 

Chairman BIGGS. Thank you, Chairman Smith. Indeed, we are 

pleased to have Ms. Rath and all of our wonderful witnesses here 

today. We are grateful that you are here. 

Our next witness today will be from my home State of Arizona, 

Mr. Timothy Franquist. He is the Arizona Department of Environmental Quality’s Air Quality Director. He previously served as the 

Air Quality Division Deputy Director and has been with ADEQ for 

more than 14 years. 

Prior to State service, Mr. Franquist worked in a variety of environmental positions, including private sector consulting, county 

government, and environmental non-government organizations. 

As Director of Air Quality, Mr. Franquist has led the division’s 

effort to become nationally recognized for the agency’s work on 

international transport of ozone, exceptional event demonstrations, 

permitting, and air quality meteorology. 

Mr. Franquist received his bachelor’s degree in environmental 

science and policy from the University of Maryland and his master’s in environmental management from ASU. Welcome, Dr. 

Franquist. 

Our third witness is Dr. Elena Craft, a senior health scientist at 

Environmental Defense Fund. For a decade, Dr. Craft has 

strategized to identify, monitor, and mitigate risks from environmental pollution from the industrial sector, as well as from within 

the transportation sector, most specifically around port areas and 

freight corridors. 

In addition, she has facilitated development of initiatives to support public health research, including helping to establish the Hurricane Harvey Environmental Health and Housing Registry in 

Houston, the first registry established after a major flood event. 

Dr. Craft’s other scientific research focuses on understanding 

health disparities associated with living in pollution hotspots. 

She holds a bachelor’s of science in biology from UNC Chapel 

Hill, a master’s of science and toxicology from North Carolina State 

University, and a Ph.D. from Duke University. Dr. Craft also holds 
19 

an adjunct assistant professorship at the University of Texas 

Health Science Center, and is a Kinder Fellow at Rice University. 

Thank you for being here, Dr. Craft. 

Our final witness today is Mr. Gregory Stella, a senior scientist 

at Alpine Geophysics, LLC. For over 25 years, Mr. Stella has coordinated with both public and private workgroups, modeling centers, and stakeholders to develop, evaluate, and apply control 

measures and program designs in support of emissions and air 

quality policy decisions. 

Prior to joining Alpine Geophysics in 2003, Mr. Stella was on 

staff at EPA’s Office of Air Quality, Planning, and Standards, 

where he managed and prepared the emission inventories, control 

strategies, and associated temporal, spatial, and speciation data 

from multiple projects. He is internationally recognized as a technical authority in the modeling and policy application of emission 

inventories for ozone, and particulate matter, pollutants, and precursors. 

Mr. Stella received his bachelor’s of science in chemical engineering from the Johns Hopkins University in Baltimore, Maryland. 

I now recognize Ms. Rath for five minutes to present her testimony. 

TESTIMONY OF MS. DIANE RATH, 

EXECUTIVE DIRECTOR, 

ALAMO AREA COUNCIL OF GOVERNMENTS 

Ms. RATH. Thank you, Mr. Chairman, and thank you for inviting 

me. I am Diane Rath, Executive Director of the Alamo Area Council of Governments. I’d also like to introduce my Board Chair who 

is with us today, Judge Chris Schuchart, who is a county judge in 

Medina County. 

I am very pleased to appear today to provide information on the 

history of public and private partnerships that have helped reduced 

ozone concentrations in the San Antonio MSA, and how background ozone, international emissions, and ozone transport contribute to San Antonio’s ozone levels. Slide, please. 

[Slide.] 

Ms. RATH. The San Antonio-New Braunfels MSA has experienced 

significant improvement in its ozone levels in the past several 

years, with a 20 percent decline from 2004 to 2016. These improvements occurred despite a population increase of nearly 600,000 

folks across the region. 

San Antonio is currently the largest city in the country with attainment with ozone national ambient air quality standards. The 

city of San Antonio added the most people of any city in the country between 2016 and 2017, and high population growth is expected 

to continue. 

Another example of the improvement in ozone levels is the number of days when any monitor exceeded an 8-hour average over 70 

parts per billion. In 2017, there were only five such days at regulatory monitors, compared to an average of 12. The region’s success 

in improving ozone levels is due, in large part, to local voluntary 

public and private initiatives to reduce ozone precursor emissions. 

Several examples are included in my written testimony. Slide, 

please. 
20 

[Slide.] 

Ms. RATH. Photochemical modeling can be used to estimate the 

contribution from other geographic areas to ozone levels at a given 

location using the Anthropogenic Precursor Culpability Assessment. APCA analysis suggests that in 2017, the maximum local 

contribution to San Antonio’s ozone at Camp Bullis C58 was 12.86 

parts per billion, or 20.5 percent. This means that 79.5 percent of 

San Antonio’s ozone is caused by emissions and transport from outside the San Antonio region; that is, outside of local control. Slide, 

please. 

[Slide.] 

Ms. RATH. A further breakdown of San Antonio ozone contribution reveals that 24.05 parts per billion, or 38.4 percent of San Antonio’s ozone, originates from international sources. Other Texas 

cities contribute 16.1 percent. It’s estimated that areas outside 

Texas contribute 25 percent to San Antonio’s ozone. 

The San Antonio-New Braunfels MSA has proven to be a leader 

when it comes to reducing ozone levels through its numerous public 

and private initiatives that limit ozone precursor emissions. These 

voluntary efforts have helped reduced San Antonio’s ozone design 

value, and is predicted to continue falling through 2023. These 

ozone reductions are all the more impressive, given the unique 

ozone transport situation that San Antonio faces with over 38 percent of ozone contribution coming from international sources. 

We urge EPA to take advantage of the flexibility in the Clean Air 

Act to recognize the impact of background ozone levels and all foreign transport on a region. It is important to acknowledge the 

amount of ozone that is produced locally and able to be impacted 

by local actions. The regulatory burden and economic consequences 

of a nonattainment designation can be devastating to a region 

when the region is not able to impact the ozone levels by its own 

actions. 

So Mr. Chairman and Committee members, I thank you for this 

opportunity to discuss the unique impact of background ozone and 

foreign transport on our region, and share the great progress we 

have made as a result of voluntary public and private initiatives 

over the concern for the health of the residents of our region. 

Thank you. 

[The prepared statement of Ms. Rath follows:] 
21 

Written Testimony of 

Diane D. Rath 

Executive Director 

Alamo Area Council of Governments 

Before the United States House of Representatives 

Committee on Science, Space, and Technology 

Subcommittee on Environment 

"San Antonio Ozone Levels and the Impact of International Emissions and Transport" 

June 21,2018 

10:00 a.m. 

2321 Rayburn House Office Building 
22 

I am Diane Rath, Executive Director of the Alamo Area Council of Governments. I am pleased to appear today 

to provide the Committee information on the history of public and private partnerships that have helped reduce 

ozone concentrations in the San Antonio-New Braunfels Metropolitan Statistical Area (MSA) over the years, 

and how background ozone, international emissions, and ozone transport contributes to San Antonio's ozone 

levels. 

The San Antonio-New Braunfels MSA has experienced significant improvement in its ozone levels in the last 

several years, with nearly a 20% decline in design value from 91 pat1s per billion (ppb) in 2004 to 73 ppb in 

20 I 6. 1 These improvements occurred despite a population increase of over 568,000 across the 8-county MSA 

during that period. 2•

3 The MSA consists of Atascosa, Bandera, Bexar, Coma!, Guadalupe, Kendall, Medina, and 

Wilson Counties. San Antonio is currently the largest city in the country with an attainment designation. The 

City of San Antonio, located in Bexar County, added the most people of any city in the United States (US) 

between 2016 and 2017, 4 and high population growth is expected to continue in the region for the foreseeable 

future. 

100 3.0 

95 2.8 

;Q 2.6 !go .. <I> 2.4 § 

.:! 85 2.2 ~ ~ 

§, 80 2.0-;::-0 ·;;; 1.8 ~ £3 75 ::; <I> 1.6 g. c: 70 2 1.4 fl. 

0 65 1.2 

60 1.0 'o:t "" co c:> N ;:!: "" co c:> N c:> "" c:> .... ...... ..... .... N N 

"" "" Q "" c:> Q Q Q Q c:> N "' N "' N "' "' N "' "' Figure I: Design Value and Population Trend and Projections for San Antonio, 2004-20235.6 

1 TCEQ. "Compliance with Eight-Hour Ozone Standard." Austin, TX. Available online: https://www.tceg.texas.oov/cgibinlcompliance/monops/8hr attainment.p!. Accessed June 7, 2018. 

2 U.S. Census Bureau, April 2017. "County Intercensal Tables: 2000-2010." Available online: https://www2.census.gov/programsillYO:§!J1!l!ll!!it!l!!hl~illl!!U!lli!iinimO!illlilllfj;QJJillY/£Q~QQjn!:Jll::ffi.lili.Accessed June 7, 2018. 

Census Bureau. American Fact Finder, March 2018. "Annual Estimates of the Resident Population: Aprill, 2010 to July 1, 

2017- United States-- Metropolitan Statistical Area; and for Puerto Rico 2017 Population Estimates.'' Available online: 

https:/ /factfinder .census.gov/faces/tableservices/jsf/pages/productview .xhtml'?src=bkmk. Accessed June 7, 2018. 

4 O'Hare, Peggy. (2018) "City's population growth largest in nation, census data shows', San Antonio Express-News, May 23. 

Available online: https://www .exnressnews.com/news/loca!larticle/City-s-population-growth-largest-in-nation-I2939249 .php. 

Accessed June 7, 2018. 5 Texas Demographic Center. '"2014 Texas Population Projections by Migration Scenario Data Tool." Available online: 

http://txsdc.utsa.edu/DataJTPEPP/Projectionsffool?fid~59C8EB01DC924235BC194ED95001697F. Accessed June 11, 2018. 6 Assumes population change due to migration at a rate equal to the 2000·2010 migration rate 
23 

Another testament to the improvement of ozone levels in San Antonio is in the number of days when any 

monitor exceeded an 8-hr average over 70 ppb in 2017 compared to the 2010-2017 annual average. These are 

days classified by the Air Quality Index (AQI) as "Unhealthy for Sensitive Groups." In 2017, there were only 

five such days at regulatory monitors, compared to a 2010-2017 average of twelve. There were 49 days with 

moderate ozone as classified by the AQI (8-hr average ozone above 54 ppb) in 2017, while the 2010-2017 

average is 64 days per year. 

The region's success in improving ozone levels is due in large part to local voluntary public and private 

partnerships to reduce ozone precursor emissions. Some of these efforts include: 

Bexar County and Cities of San Antonio, Leon Valley, and Seguin Anti-Idling Ordinances; 

CPS Energy's Save For Tomorrow Energy Plan (STEP) to reduce demand for electricity generated by 

coal-fired power plants, equal to shutting down a medium-sized coal plant; 

CPS Energy met its goal of 1,500 megawatts (MW) of renewable energy capacity two years ahead of 

schedule through the management and expansion of a diverse energy generation portfolio, including 

wind, rooftop solar, and utility-scale solar; the 1,500 MW amounts to 20% of CPS Energy's total 

generation capacity; 

Participating in the Texas Emission Reduction Program (TERP) to facilitate turnover of older and dirtier 

diesel engines; engage in community outreach to spread awareness ofTERP among local industry and 

business leaders; 

Installing selective non-catalytic reduction at cement kilns in Bexar and Coma! Counties; 

Equipment and lighting retrofits by San Antonio Water System (SAWS) using incentives from CPS 

Energy's Commercial Energy Efficiency Program; SAWS biogas capture from new Dos Rios water 

treatment facility; 

City of San Antonio ban on coal tar sealants; San Antonio is the largest city in the country with such an 

ordinance~ 

VIA Metropolitan Transit (VIA) began converting its diesel bus fleet to compressed natural gas (CNG) 

in April2017; VIA's new CNG fueling facility is the largest in North America; and 

Investments in the latest technology by both the energy industry in the Eagle Ford shale and the cement 

industry to reduce emissions. 

One example of technology employed by the cement industry to reduce emissions is the implementation of 

SkyMine® technology. Developed at San Antonio's Southwest Research Institute and implemented in 

September 2015, SkyMine® removes carbon dioxide (C02), sulfur oxides (SOx), and nitrogen oxides (NOx) 

from industrial waste streams and transforms them into marketable products like baking soda, bleach, and 

hydrochloric acid. The Capitol Aggregates cement plant in San Antonio was the first facility in the U.S. to use 

this technology. Sky Mine® requires 30% less energy to operate compared to traditional carbon removal 

techniques. 7 

Future improvements to local ozone levels will continue to occur as CPS Energy's Deely Units 1 and 2 will be 

retired in 20!8, resulting in over seven tons ofNOx reduced per summer day. Two other large coal-fired plants 

in central Texas were retired in January 2018. In addition, VIA has committed to convert its entire diesel bus 

fleet to CNG by 2020. 

7 Capitol Aggregates, Inc. ''Capitol Skymine®: Pro-Business, Pro-Environment." Available online: 

http://www.capitolaggregates.com/s/Sustainability~Skyonic. Accessed June 7, 2018. 
24 

Thanks to these united efforts to reduce ozone precursors, photochemical modeling reviewed by the US 

Environmental Protection Agency (EPA) and the Texas Commission on Environmental Quality (TCEQ) 

projects that Bexar County monitors will meet the 2015 ozone NAAQS by 2020, which is earlier than would be 

required under a marginal nonattainment designation. Every regulatory monitor in the area (CAMS 23, CAMS 

58, and CAMS 59) is projected to be well below the 2015 standard by 2023. 

74 

72 

60 

58 

CAMS23 CAMS 58 CAMS 59 

Figure 2: Projected Change in San Antonio-New Braunfels MSA Eight-Hour Design Values with a 2017 Base Line, 

2020 and 20238 

Photochemical modeling can be used to estimate the contribution from other geographic areas to ozone levels at 

a given location using the Anthropogenic Precursor Culpability Assessment (APCA). APCA analysis suggest 

that in 2017, the maximum local contribution to San Antonio's ozone at Camp Bullis C58 on days> 60 ppb was 

12.86 ppb, or 20.5%. This means that 79.5% of San Antonio's ozone is caused by emissions and transport from 

outside the San Antonio-New Braunfels MSA, that is, outside oflocal control. 

8 AAMPO, November 2017. "Ozone Analysis ofthe 2012 Ozone Season Photochemical Modeling Episode." P. 8-7. San Antonio, TX. 
25 

Figure 3. Local \'S. Transported O:::o/1(' .Hea.'mred at CAJ1S 58 Camp Bull/\". lO/ 7 

A iurthcr hreakdown of San Antonio ozone contribution reveals that 24.05 ppb, or 38.4% of San Antonio ·s 

ozone on days> 60 ppb originates ffom international sources. Specifically, these arc ozone precursors or ozone 

located outside of the black box labeled '"RPO 36 km". 

Figure.../. ,Vested }1/wrochcmica/ t!ode!mg Grid; tin· O::one Semon _~nJ 2 E'pisodc 

•J AACOG. March 2018. "International Contribution to Local Ozone in the San Antonio-i'ie'>v Braunk!s MSA 2017 and 2023." San 

Antonio, TX. Email correspondence to TCEQ. 

IG TCEQ. "Texas Air Quality Modding ,_Domain:-.", Austin. Texas. Available online: 

http:.·iwv-;w.tceq.te"Xas.gOY·airqualityiainnocL riderR/modcling'domain. Acces:-.ed June 7, 201 R. 
26 

It is estimated that areas within Texas (including the San Antonio-New Braunfels MSA) contribute to 36.6% of 

San Antonio's ozone. Areas outside Texas but within the modeling domain (including southern Canada, 

northern Mexico, the northwest Caribbean, and adjacent offshore areas) contribute 25% to San Antonio's 

ozone. A summary of modeled contribution to San Antonio area ozone by geographic region is provided in 

Figure 5. 

60 ppb, 2017 11 

Daily local meteorological observations during high ozone events show that elevated ozone levels typically 

occur in the days following the passage of a frontal boundary. In the absence of large-scale weather features like 

fronts, southeasterly flow dominates. This flow regime transports relatively clean air(< 55 ppb ozone) from the 

Gulf of Mexico over the San Antonio region. When a front passes through south Texas, northerly winds 

transport relatively dirty continental air containing ozone and ozone precursors from major metropolitan areas 

and heavily-traveled transportation corridors like Interstate 35. Under these conditions, ozone concentrations 

typically rise to moderate levels ( 55-70 ppb ). As frontal boundaries either dissipate or continue to move south 

away from the region, higb pressure in the southeastern U.S. becomes reestablished, and southeasterly flow 

begins to return to the San Antonio region. The highest ozone levels coincide with this flow transition from 

northerly to southeasterly, which is most pronounced at the Camp Bullis CAMS 58 monitor. Wind roses 

comparing morning and afternoon wind direction and speed at CAMS 58 on high ozone days clearly show this 

flow reversal (Figure 6). Ozone levels fall back to below moderate levels about a day after southeasterly flow 

returns. 

11 AACOG, March 2018. "International Contribution to Local Ozone in the San Antonio· New Braunfels MSA, 2017 and 2023." San 

Antonio, TX. Email correspondence to TCEQ. 
27 

Land falling tropical cyclones in the southcastem lJS. can also cause a spike in local ozone levds by creating a 

similar now reversal pattern seen after a frontal passage. When San Antonio is \Vest of a large cyclonic 

(counterclockwise) circulation, northerly winds arc observed locally, As the weakening tropical cyclone moves 

farther inland and away from San Antonio, its intluence on local weather diminishes, and southeasterly flow 

returns. initiating a high ozone event. The most recent such occurrence was HuiTicanc Irma in September 2017. 

whose landfall in Florida on September 10 triggered a high ozone event in San Antonio on September 13, Other 

meteorological characteristics that are conducive to high ozone in San Antonio are low humidity, weak or 

variable steering flow. a large diurnal temperature difference, and a rapid rise in mixing height during the day. 

Figure 6,' Wind Roses Comparing Morning and Afternoon Winds at C>LvfS 58 on O~one Davs > 70 pph, 21110-

1017 

The San Antonio-New Braunfels MSA has proven to be a leader when it comes to reducing ozone levels 

through its numerous public and private initiatives that limit ozone precursor emissions. These efforts have 

helped reduce San Antonio's ozone design value li'om 91 ppb in 2004 to 73 ppb in 2016, and is predicted to 

continue falling through 2023. These ozone reductions arc all the more impressive given the unique ozone 

transport situation that San Antonio faces, with over 38%) of ozone contribution coming from international 

sources. 

We urge EPA to take advantage of the llexibility in the Clean Air Act to evaluate and actively consider during 

NAAQS designation the impact of background ozone levels and all foreign transport on a region. It is 

important to acknowledge the amount of ozone that is produced locally and able to be impacted by local 

actions. The regulatory burden and economic conseque-nces of a nonattainmcnt designation can be devastating 

to a region \vhcn the region is not able to impact the ozone levds by its own actions. 

Thank you for pro>,iding this opportunity to discuss the unique impact of background ozone and foreign 

transpm1 on our region and share the great progress we have made as a result of the voluntary public-private 

partnerships, 
28 

Diane Rath has served as Executive Director of AACOG since December 

2014. In this capacity, she oversees 300 employees in 11 program areas 

with a budget of $50 million. During her tenure. AACOG has been 

recognized with national awards from NADO recognizing both Innovation 

and Transportation Partnerships. 

Before joining AACOG, Ms. Rath served as Senior Vice President at ResCare 

Workforce Services, with oversight responsibility for operations in over 300 

locations in 28 states with 2200 employees and a budget of $223 million. 

In 1996, then Governor George W. Bush appointed her as Chair and Commissioner for the Texas 

Workforce Commission. where she served until 2008. During her tenure, she oversaw the 

consolidation of 28 programs from 10 different state agencies to form a $1.2 billion agency with 

responsibility for services involving federal programs from the U.S Department of Labor. Health 

and Human Services. and two other federal agencies. In 2007, Rath was nominated by President 

George W. Bush as Assistant Secretary of Administration for Children and Families at U.S. Health 

and Human Services. During this time she became recognized as a national leader in workforce 

development, forging partnerships with economic development and educational entities to meet 

the workforce needs of Texas businesses. 

A physical therapist by background, Ms. Rath attended TCU, and graduated from UTMBGalveston. 

She is active in the San Antonio community and currently serves (or served) on numerous boards 

and committees which include 

National Association of Regional Councils. Executive Director Council, 2017-

Frost Bank- San Antonio, Advisory Board Member, 2003-present 

Texas Conservative Coalition Research Institute, Board Member. 2003-present 

• Valero Alamo Bowl, Board Member, 1994-present, Chair 2002 

• San Antonio Airport Advisory Commission, 2015 - present 

Lone Star Rail District Board, 2015-present 

San Antonio Mobility Coalition (SAMCo) Board Member, 2015- present, Treasurer 2016-

2017 

American Public Human Services Association Policy Council, 2007-2008 

Texas Public Education Reform Foundation. Board Member, 2006-2010 

Bexar County United Way, Board Member 1998-2004 

Greater San Antonio Chamber of Commerce. Board of Directors 1993-96, Vice-Chair 

1993 

JPMorganChase - San Antonio, Advisory Board Member, 1992-2003 

Texas Council on Workforce & Economic Competitiveness. 1995-2003, Chair 1995-1996 

Texas Department of Commerce, Board Member 1995-1996 

• San Antonio Development Agency, Vice Chair, 1990-94 

• San Antonio Water System Board, Vice-Chair 1992-94 

Texas Rehabilitation Commission, Board Member 1989-1992 

• Texas Board of Physical Therapy Examiners. 1981-1983 
29 

Mr. NORMAN. [Presiding.] Thank you, Ms. Rath, and I too want 

to take this opportunity to thank each of you for devoting your time 

and talent to educating us on the issue. 

I now recognize Mr. Franquist for five minutes to present his testimony. 

TESTIMONY OF MR. TIMOTHY FRANQUIST, 

AIR QUALITY DIVISION DIRECTOR, 

ARIZONA DEPARTMENT OF ENVIRONMENTAL QUALITY 

Mr. FRANQUIST. Thank you. Mr. Chairman, Members of the Committee, my name is Timothy Franquist, and I am the Air Quality 

Director at the Arizona Department of Environment Quality, and 

I appreciate the opportunity to offer testimony today. 

The Clean Air Act has done a remarkable job of reducing air pollution across the county for the past 48 years from industry and 

vehicles. Now, however, we face a new air quality challenge: global 

air pollution, specifically, air pollution that is transported to the 

U.S. in such quantities to cause areas of the country to exceed the 

National Ambient Air Quality Standards. Unfortunately, the Clean 

Air Act is ill-equipped to address this new air quality problem in 

terms of protecting public health and our local economies. 

The U.S. EPA has conducted ozone modeling for U.S. background, or what is more commonly referred to as international 

transport, several times over the past three years. The models continue to indicate that ozone concentrations are increasing from 

international sources and impacting the U.S. 

The most recent U.S. model indicates that over 83 percent of 

ozone in southern Arizona is attributed to international sources. 

Arizona is not only impacted by Mexican emissions, 65 percent of 

the ozone in the Southwest is attributed to international transport 

from Asia, according to a surface ozone study conducted by a team 

of researchers from NOAA, Princeton University, Columbia University, and the U.S. EPA. 

The surface ozone study further indicates that during summertime in the western U.S. ‘‘increasing Asian emissions approximately offset the benefits of U.S. emissions reductions.’’ 

Beginning in May 2017, the Arizona Department of Environmental Quality installed an ozone monitor in San Luis Rio Colorado, Mexico, to determine the impacts of international transport 

on Yuma, Arizona, a new ozone nonattainment area proposed by 

the U.S. EPA as of April 2018. Our preliminary analysis indicates 

that prevailing winds from the south and increasingly high levels 

of ozone originating south of the U.S. border are causing Yuma to 

exceed the federal ozone standard. 

Because Yuma exceeds the 2015 Ozone standard, the Clean Air 

Act will require the State of Arizona to develop a state implementation plan for the area. Yuma will be subject to emission offsets 

for new large businesses or major expansions to existing businesses 

and those sources will be required the install extremely expensive 

emission control equipment before operating. Yuma is not a heavy 

industrial or urban area and therefore, it does not generate the 

requisite emission offsets, which ultimately discourages new or expanding business in the area. 
30 

The only relief for Yuma under the Clean Air Act is the state to 

pursue an international transport demonstration, but we can only 

do that demonstration after three years of an area not meeting the 

standard. Yuma will remain in perpetual nonattainment until 

international emissions decrease to the extent that Yuma attains 

the ozone standard. The international transport demonstration 

does nothing to better protect Yuma residents from the health impacts of international pollution or lessen the burden on their local 

economy. 

The negative health effects of ozone is well documented; as is 

poverty’s negative effect on public health. The impact of nonattainment on Yuma’s public health and economy creates an incredibly 

dire situation for a primarily agricultural community of 100,000 

residents, 19 percent of which live below the poverty line. 

The World Bank states in a report entitled ‘‘Poverty and Health’’ 

that ‘‘Poverty is a major cause of ill health and a barrier to accessing health care when needed.’’ 

According to a study authored by Michael McCally, MD, and his 

colleagues, people living in countries with a higher Gross National 

Product have a longer life expectancy. In short, public health is not 

just about clean air, it’s also about a healthy economy. 

Finding state-level solutions for ozone nonattainment areas are 

made infinitely more complicated when the area is significantly impacted by international transport of air pollution, as we are in Arizona. Therefore, we must look to our federal agencies and representatives for relief to the international air pollution transport 

problem so that the recipients of pollution are not punished, but 

protected. 

The Clean Air Act has not been significantly revised since 1990. 

As Arizona and the U.S. confront the growing challenge of global 

air pollution impacts on the U.S., I urge Congress to seriously consider meaningful revisions to the Clean Air Act to address international transport of air pollution. 

Senator Flake has introduced Senate Bill 2825, which helps remove some of the negative economic impacts to areas of the U.S. 

that do not meet the Ozone standard due to international transport, while maintaining adequate air quality control measures to 

ensure that public health and the environment are protected. Senate Bill 2825 would be a major step in protecting places like Yuma, 

Arizona, and the West from international air pollution. 

Thank you. 

[The prepared statement of Mr. Franquist follows:] 
31 

Testimony 

U.S. House of Representative Committee on Science, Space, & Technology 

Subcommittee on Environment 

Thursday, June 21, 2018 

By 

Timothy Franquist, Air Quality Director 

Mr. Chairman, members of the committee. My name is Timothy Franquist. I am the Air Quality Director 

at the Arizona Department of Environmental Quality and; I appreciate the opportunity to offer 

testimony today. 

The Clean Air Act has done a remarkable job of reducing air pollution across our county for the past 48 

years from industry and vehicles. Now, however, we face a new air quality challenge: global air 

pollution, specifically, air pollution that is transported to the U.S. in such quantities to cause areas of our 

country to exceed the National Ambient Air Quality Standards (NAAQS). Unfortu·nately, the Clean Air Act 

is ill equipped to address this new air quality problem in terms of protecting public health and our local 

economies. 

The U.S. EPA has conducted ozone modeling for U.S. background, or what is more commonly referred to 

as international transport, several times over the past three years. The models continue to indicate that 

ozone concentrations are increasing from international sources and impacting the U.S. The most recent 

U.S. EPA model indicates that over 83% of ozone in Southern Arizona is attributed to international 

sources (Attachment A). 

Arizona is not only impacted by Mexican emissions, 65 percent of the ozone in the Southwest is 

attributed to international transport from Asia, according to a surface ozone study conducted by a team 

of researchers from NOAA, Princeton University, Columbia University, and the U.S. EPA (Attachment B). 
32 

The surface ozone study further indicates that during summertime in the Western U.S., "increasing 

Asian emissions approximately offset the benefits of U.S. emissions reductions." 

Beginning in May 2017, the Arizona Department of Environmental Quality installed an ozone monitor in 

San luis Rio Colorado, Mexico, to determine the impacts of international transport on Yuma, Arizona, a 

new ozone nonattainment area proposed by the U.S. EPA as of April 2018. Our preliminary analysis 

indicates that prevailing winds from the south and increasing high levels of ozone originating south of 

the U.S. border are causing Yuma to exceed the federal ozone standard (Attachment C). 

Because Yuma exceeds the 2015 Ozone standard, the Clean Air Act will require the State of Arizona to 

develop a state implementation plan for the area. Yuma will be subject to emission offsets for new large 

businesses or major expansions to existing businesses and those sources will be required the install 

extremely expensive emission control equipment before operating. Yuma is not a heavy industrial or 

urban area and therefore, it does not generate the requisite emission offsets, which ultimately 

discourages new or expanding business in the area. 

The only relief for Yuma under the Clean Air Act is for the State to pursue an international transport 

demonstration, but we can only submit that demonstration after three years of the area not meeting 

the standard. Yuma will remain in perpetual nonattainment until international emissions decrease to the 

extent that Yuma attains the ozone standard. The international transport demonstration does nothing 

to better protect Yuma residents from the health impacts of international pollution or lessen the burden 

on their local economy. 

The negative health effects of ozone is well documented; as is poverty's negative effect on public health. 

The impact of nonattainment on Yuma's public health and economy creates an incredibly dire situation 

for a primarily agricultural community of 100,000 residents, 19 percent of which, live below the poverty 
33 

line'. The World Bank states in a report entitled, "Poverty and Health", that "Poverty is a major cause of 

ill health and a barrier to accessing health care when needed." (Attachment E) According to a study, 

authored by Michael McCally, MD and his colleagues, people living in countries with a higher Gross 

National Product have a longer life expectancy (Attachment F). In short, public health is not just about 

clean air, it's also about a healthy economy. 

Finding state-level solutions for ozone nonattainment areas are made infinitely more complicated when 

the area is significantly impacted by international transport of air pollution, as we are in Arizona. 

Therefore, we must look to our federal agencies and representatives for relief to the international air 

pollution transport problem so that the recipients of pollution are not punished, but protected. 

The Clean Air Act has not been significantly revised since 1990. As Arizona and the U.S. confront the 

growing challenge of global air pollution impacts on the U.S., I urge congress to seriously consider 

meaningful revisions to the Clean Air Act to address international transport of air pollution. Senator 

Flake has introduced Senate Bill2825, which helps remove some of the negative economic impacts to 

areas of the U.S. that do not meet the Ozone standard due to international transport, while maintaining 

adequate air quality control measures to ensure that public health and the environment are protected. 

Senate Bill 2825 would be a major step in protecting places like Yuma, Arizona, and the West from 

international air pollution. 

Thank you and I am happy to take any questions at this time. 

1 Source: https:/ /www .census.gov/quickfacts/fact/table/yumacountyarizona/PST045217 
34 

Attachment 

A 
35 

U.S. EPA International Transport Modeling 

Summary of Modeling Results for Yuma, AZ 

Model Average AZ CA Mex/Can Biogenics Boundary USB (three 

DV previous columns 

combined) 

Jan 2015 70.7 6.8% 23.5% 6.8% 5.4% 56.8% 69% 

Aug 2015 70.7 6.1% 19.5% 7.2% 3.8% 61.3% 72.3% 

Sept 2016 71.5 6.00/o 18.2% 7.6% 3.3% 62.8% 73.7% 

Dec2016 68.9 4.9% 8.1% 13.3% 2.8% 68.8% 84.9% 

Mar 2018 70.4 5.5% 8.00/o 14.1% 3.1% 66.3% 83.5% 

Summary Modeling Results of Adjacent Locations to Yuma, AZ (March 2018) 

Average DV Mex/Can Biogenics Boundary USB (three 

previous columns 

combined) 

Imperial, CA 79.0 23.7% 2.6% 55.2% 81.5% 

San Diego, CA 69.4 20.1% 2.3% 37.9% 60.3% 

Dona Ana,NM 67.1 20.3% 4.5% 55.8% 80.6% 

El Paso, TX 67.6 27.1% 4.4% 52.2% 83.7% 

Brewster, TX 67.9 8.2% 3.6% 75.5% 87.3% 

Summary of Modeling Results for Reference 

USB USB 

Maricopa, AZ 55.6% Chicago, ll 38.6% 

San Bernardino, 44.5% Atlanta, GA 31.6% 

CA 
36 

Long Island, NY 34.2% Orlando, FL 42.8% 

Fairfield, CN 30.8% Baltimore, MD 30.2% 

Sheboygan, WI 35.3% Denver, CO 52.9% 

Modeling Boundary Map 

Data Sources of U.S. EPA Modeling: 

2008 NAAQS Ozone Trans port Modeling 

January 2015-https :1/www .epa.gov /airinarkets/januarv-2015-memo-and~nformation-0 

August/November 2015-https://www.epa.gov/airmarkets/proposed-cross-state-air-oollution-uodate-rule 

September 2016 -https://www.epa.gov/airmarkets/final-cross-state-air-oollution-rule-uodate 

2015 NAAQS Ozone Transport Modeling 

December 2016 https:l/www.epa.gov/airmarkets/notice-data-availabilitv-oreliminarv~nterstate-ozonetranspqrt-modeling-data-2015-ozone 

March 2 018- https ://www .epa.gov /ai rmarkets/march-20 18-memo-and-supplemental-informatipn-regardingi nters tate-transport-sios-20 15 

Technical Notes: 

Mex/Ca n contribution is anthropogenic emissions from the portions of Mexico and Canada i nsidethe 

boundary 

Boundary contribution is all (anthropogenicand natural sources) emissions for everything outside the 

boundary, a global model is used to determine this 

EPA's definition ofU.S. Background (USB) as ozone formed from anysources other than US manmade 

emissions (which would include Mexico/Canada, Biogenics, and Boundary) 
37 

Attachment 

B 
38 

Atmos. Chern. Phys., 17,2943-2970,2017 

www.atmos-chem-phys.net/17/2943120 171 

doi: I 0.5194/acp-17-2943-2017 

© Author(s) 2017. CC Attribution 3.0 License. 

alii 

Atmospheric @G U 

Chemistry 

and Physics 

US surface ozone trends and extremes from 1980 to 2014: 

quantifying the roles of rising Asian emissions, 

domestic controls, wildfires, and climate 

Meiyun Lin 1 •

2, Larry W. Horowitz2, Richard Payton3, Arlene M. Fiore4, and Gail Tonnesen3 

1 Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ 08540, USA 2NOAA Geophysical Fluid Dynamics Laboratory, Princeton, NJ 08540, USA 

Jus Environmental Protection Agency, Region 8, Air Program, Denver, CO 80202, USA 4Lamont-Doherty Earth-Observatory and Department of Earth and Environmental Sciences, 

Columbia University, Palisades, NY 10964, USA 

Correspondence to: Meiyun Lin (rneiyun.lin@noaa.gov) 

Received: 4 December 2016- Discussion started: 7 December 2016 

Revised: 2 February 2017- Accepted: 6 February 2017- Published: l March 2017 

Abstract, US surface 03 responds to varying global-toregional precursor emissions, climate, and extreme weather, 

with implications for designing effective air quality control policies. We examine these conjoined processes with 

observations and global chemistry-climate model (GFDLAM3) hindcasts over 1980-2014. The model captures the 

salient features of observed trends in daily maximum 8 h average OJ: (I) increases over East Asia (up to 2 ppbyC1

), 

(2) springtime increases at western US (WUS) rural sites 

(0.2-0.5 ppb yr- 1) with a baseline sampling approach, and 

(3) summertime decreases, largest at the 95th percentile, and 

wintertime increases in the 50th to 5th percentiles over the 

eastern US (EUS). Asian NOx emissions have tripled since 

1990, contributing as much as 65% to modeled springtime 

background OJ increases (0.3-0.5 ppb yr- 1) over the WUS, 

outpacing 03 decreases attained via 50% US NOx emission 

controls. Methane increases over this period contribute only 

15% of the WUS background 03 increase. Springtime 03 

observed in Denver has increased at a rate similar to remote 

rural sites. During summer, increasing Asian emissions approximately offset the benefits of US emission reductions, 

leading to weak or insignificant observed 03 trends at WUS 

rural sites. Mean springtime WUS 03 is projected to increa..o;;e 

by ~ IOppb from 2010 to 2030 under the RCP8.5 global 

change scenario. While historical wildfire emissions can enhance summertime monthly mean 03 at individual sites by 

2-8 ppb, high temperatures and the associated buildup of OJ 

produced from regional anthropogenic emissions contribute 

most to elevating observed summertime 03 throughout the 

USA. GFDL-AM3 captures the observed interannual variability of summertime EUS OJ. However, 03 deposition sink 

to vegetation must be reduced by 35% for the model to accurately simulate observed high-03 anomalies during these~ 

vere drought of 1988. Regional NOx reductions alleviated 

the 03 buildup during the recent heat waves of 2011 and 

2012 relative to earlier heat waves (e.g., 1988, 1999). The 

03 decreases driven by NOx controls were more pronounced 

in the southeastern US, where the seasonal onset of biogenic 

isoprene emissions and NOx-sensitive 03 production occurs 

earlier than in the northeast. Without emission controls, the 

95th percentile summertime 03 in the EUS would have increased by 0.2-0.4 ppb yr- 1 over 1988-2014 due to more frequent hot extremes and rising biogenic isoprene emissions. 

1 Introduction 

Within the United States, ground-level 03 has been recognized since the 1940s and 1950s as an air pollutant detrimental to public health. Decreases in summertime 03 were 

observed in parts of California and throughout the EUS (e.g., 

Cooper et al., 2012; Simonet al., 2015), following regional 

NOx controls after the lowering of the US National Ambient Air Quality Standard (NAAQS) for 03 in 1997 to 84 ppb. 

On the basis of health evidence, the NAAQS level for 03 

Published by Copernicus Publications on bebalf of the European Geosciences Union, 
39 

2944 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

has been further lowered to 75 ppb in 2008 and to 70 ppb in 

2015 (Federal Register, 2015). There are concerns that ris· 

ing Asian emissions and global methane (Jacob et al., 1999; 

Lin el al., 2015b), more frequent large wildfires in summer 

(e.g., Jaffe, 2011; Yang et al., 2015; Abatzoglou eta!., 2016), 

and late spring deep stratospheric 03 intrusions (Lin et aL, 

2012a, 2015a; Langford et al., 2014) may pose challenges in 

attaining more stringent 03 standards in high-elevation WUS 

regions. A wanning climate would also offset some of the 

air quality improvements gained from regional emission controls (e.g., Fiore et al., 2015). Quantitative understanding of 

sources of 03 variability on daily to multi-decadal tirnescales 

can provide valuable information to air quality control managers as they develop 03 abatement strategies under the 

NAAQS. Here we systemically investigate the response of 

US surface 03 means and extremes to changes in Asian and 

North American anthropogenic emissions, global methane, 

regionat heat waves, and wildfires over the course of 35 years 

from 1980 to 2014, using observations and chemistry-climate 

model (GFDL-AM3) hindcasts (Lin et al., 2014, 2015a, b). 

Rapid economic growth has led to a tripling of 03 precursor emissions from Asia in the pa')t 25 years (e.g., Granier 

et al., 2011; Hilholl et al., 2013). Observed I h 03 mixing 

ratios can frequently reach 200-400 ppb during regional pol· 

!uti on episodes in eastern China (Wang et al., 2006; Li et al., 

2016), with a seasonal peak in the late spring to early summer (Wang et al., 2008; Lin et al., 2009). A synthesis of available observations from the mid-1990s to the 2000s indicates 

increases of 1-2 ppb yC 1 in spring to summer 03 in China 

(Ding et al.. 2008; Ma et al., 2016; Sun et al., 2016). Long· 

range transport of Asian pollution plumes towards western 

North America has been identified by aircraft and satellite 

measurements and in chemical transport models (e.g., Jaffe et 

al., 1999; Fiore eta!., 2009; Brown-Steiner and Hess, 2011; 

Lin et al., 2012b; Huang et al.. 2013; Verstraeten et al., 2015). 

Systematic comparison of observed and modeled long-term 

03 trends over Asia is lacking in the published literature but 

is needed to establish confidence in models used to assess the 

global impacts of rising Asian emissions. 

Model simulations indicate that import of Asian pollution enhances mean WUS surface 03 in spring by ......, 5 ppb 

(Zhang et al., 2008; Lin et al., 20 l2b ), and occasionally con· 

tributes 8-15 ppb during springtime pollution episodes observed at rural sites (Lin et al., 2012b) as supported by in situ 

aerosol composition analysis (VanCuren and Gustin, 2015). 

Stratospheric intrusions can episodically increase daily 8 h 

average surface 03 by 20-40 ppb, contributing to the high· 

est observed 03 events at high~elevation WUS sites (Lin et 

al., 20 12a, 20 !Sa), in addition to pollution transport from 

California (e.g., Langford et al., 2010). In the densely populated EUS, both changes in regional anthropogenic emissions and air pollution meteorology have the greatest impacts 

on summer surface 03 during pollution episodes (e.g., Jacob 

and Winner 2009; Rieder et a!., 2015; Porter et al., 2015; 

Pusede et al.. 20 15). Discerning directly the effect of climate 

Atmos. Chern. Phys., 17,2943-2970,2017 

change on air quality from long-term observation records of 

03 would be ideal, but concurrent trends in precursor emissions and large internal variability in regional climate impede 

such an effort. It is difficult lo separate the impacts of changes 

in global-to-regional precursor emissions and different mete~ 

orological factors on 03 at given locations without the benefit 

of multiple sensitivity experiments afforded by models. 

On the other hand, process-oriented assessments of the 

models are needed to build confidence in their utility for assessing pollution control strategies. estimating tropospheric 

03 radiative forcing and projecting pollution extremes under future climate scenarios (e.g., Monks et al., 2015). A 

number of studies show that global models capture observed 

decreases in summertime 03 over the EUS during 1990-

2010, but have difficulty simulating 03 increases measured 

at remote high~elevation sites that are believed to represent 

hemispheric-scale conditions with little influence from fresh 

local pollution (hereafter referred to as "baseline") (e.g., 

Lamarque et al., 2010; Koumoutsaris and Bey, 2012; Par· 

rish et al.. 2014; Brown-Steiner et al., 2015; Strode et a!., 

2015). Recently, Lin et al. (2015b) examined the representa· 

tiveness of 03 trends derived from sparse measurements in 

the free troposphere over the WUS, originally reported by 

Cooper et al. (20 10) and used in prior model evaluations. 

They found that discrepancies between observed and simulated 03 trends reflect mea.;;urernent sampling biases. Here 

we seek additional insights into the causes of the modelobservation disagreement at the WUS rural sites with continuous, high~frequency measurements. Notably, we reconcile observed and simulated 03 trends at these sites with a 

baseline sampling approach in the model. 

Our goal in this paper is 2-fold: first, to systematically 

evaluate how well the GFDL-AM3 model represents trends 

and variability of surface 03 observed at rural sites across 

the US; second, to examine changes in US surface 03 means 

and extremes in a suite of multi-decadal hindcast simulations 

designed to isolate the response of 0 3 to increases in Asian 

anthropogenic emissions, North American emission controls, 

rising global methane, wildfires, and interannual variability 

in meteorology. We examine trends across the entire probability distribution of 03 concentration, which is crucial to 

assessing the ability of models to simulate the surface 03 

response under different temperature and chemical regimes 

depending on seasons, geographical location, and regional 

transport patterns. Specifically, we evaluate the trends separately for the 5th, 50th and 95th percentiles of the 03 con· 

centration distribution in spring (MAM), summer (JJA), autumn (SON), and winter (DJF). 

Section 2 briefly describes the observational records, 

model experiments, and analysis approach. As a first step 

towards assessing our understanding of the impacts of rising Asian emissions, we briefly review Asian 03 trends from 

observations in recent publications and evaluate modeled 

trends (Sect 3). We then focus our analysis on the US, using both observations and models to assess the response of 

www.atmos-chem-phys.net/17/2943/2017/ 
40 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2945 

VS surface 03 to changes in background 03, regional anthropogenic emissions and meteorology (Sect. 4). In Sect. 5, 

we further separate the influence of background on WUS 03 

into components driven by rising Asian anthropogenic emissions, glohal methane. and wildfires. We quantify the contribution of these factors to surface 03 in both rural areas such 

as national parks (Sect. 5.1 to 5.3) and in densely populated 

regions such as the Denver metropolitan area (Sect. 5.4 ). After evaluating historical trends, we additionally draw upon 

two simulations following the 2lst century RCP4.5 versus 

RCP8.5 global change scenarios to project WUS 03 through 

2050 (Sect. 5.2). Section 6 examines how the EUS summertime 03 probability distribution and pollution extremes respond to large-scale heat waves, droughts, and regional NOx 

reductions over the past decade, and how well our model simulates the observed features. Finally, we summarize in Sect. 7 

the key drivers of US surface 03 trends and extremes and discuss the implications of this study. 

2 Model and observations 

2.1 Chemistry-climate model experiments 

The GFDL-AM3 model includes interactive stratospheretroposphere chemistry and aerosols on a cubed sphere grid 

with a resolution of approximately 200 x 200 km2 (Donner 

et a!., 20 II). Table 1 summarizes the meteorology, radiative forcing agents, and emissions used in each experiment. 

The hindcast simulations (1979-2014) are nudged to the 

NCEP/NCAR reanalysis zonal and meridional winds using 

a height-dependent nudging technique (Lin et al., 2012b). 

Biogenic isoprene emissions and lightning NOx are tied to 

model meteorology (Guenther eta!., 2006; Rasmussen eta!., 

2012) and thus can respond to changes in climate, whereas 

soil NO.t and chemical dry deposition velocities are set to a 

monthly climatology (Naik et al., 2013), with a diurnal cycle applied for 03 dry deposition. To investigate the possible 

influence of drought on 03 removal (e.g., Emberson et al., 

20l3), we additionally conduct a sensitivity simulation for 

1988 with reduced 03 deposition velocity (see Sect. 6). Our 

BASE simulation and two additional simulations with modi tied emissions (F!XEMIS and IAVPIRE) were previously 

used to interpret the causes of increasing autumnal 03 measured at Mauna Loa Observatory in Hawaii since 1974 (Lin 

et aL, 2014), interannual variability of springtime 03 (Lin et 

al., 20 I5a) and the representativeness of free tropospheric 03 

measurements over the WUS (Lin et al., 2015b). 

With anthropogenic emissions and methane held constant 

(Table 1), the FIXEMIS and IAVFIRE simulations isolate 

the influence from meteorology and wildfire emissions. respectively. In IAVASIA, anthropogenic emissions from East 

Asia (15-50" N, 95-160° E) and South Asia (5-35° N, 50-

950 E) are allowed to vary from year to year as in BASE, 

while anthropogenic emissions in the other regions of the 

www.atmos-chem-phys.net/17/2943/2017/ 

world, global methane and wildfire emissions are held constant as in FIXEMIS. In IAVCH4 , global methane is allowed 

to vary over time as in BASE, but with anthropogenic and 

wildfire emissions held constant as in FIXEMIS. The IAVASIA and IAVCH4 simulations thus isolate the role of rising 

Asian anthropogenic emissions and global methane, respectively, by contrasting with the FIXEMIS simulation. Both 

BASE and IAVCH., simulations apply observed time-varying 

methane concentrations as a lower boundary condition for 

chemistry (Supplement Fig. S I). Thus, underestimates in historical methane emissions reported recently by Schwietzke 

et a!. (20 16) do not affect our results. We quantify the total contributions to surface 03 from meteorological variability, stratosphere-to-troposphere transport, pollution from foreign continents and 03 produced by global methane, lightning NOx, wildtlres and biogenic emissions with the Background simulation, in which North American anthropogenic 

emissions are zeroed out relative to BASE. We additionally 

draw upon two simulations with the GFDL Coupled Model 

CM3 following the 21st century RCP global change scenarios to project changes in WUS 03 through 2050. Details of 

these CM3 simulations were described in John eta!. (2012). 

2.2 Anthropogenic and biomass hurning emissions 

We first examine how well the emission inventories in AM3 

BASE represent changes in regional NOx emissions over 

recent decades inferred from satellite measurements of tropospheric vertical column density (VCDtropl of N02. The 

combined record of GOME and SCIAMACHY shows that 

VCDtrop NO, over the highly polluted region of eastern 

China almost tripled during 199t;-:2011 (Fig. I a). In contrast, VCDtrop N02 over the EUS decreased by -50% in 

the 2000s (Fig. 1 b) due to NOx State Implementation Plans 

(commonly known as the NOx SIP Call) and many rules that 

tighten emission standards for mobile sources (McDonald 

et al., 2012). Similar decreases occurred in WUS cities, resulting from the NOx control programs to achieve 03 and 

regional haze planning goals. These trends are consistent 

with those reported by a few recent studies (e.g., Hitboll et 

aL 20 13), including those using OM! N02 data (Russell et 

al., 20 12; Duncan et al., 20 16). For comparison with satellite data, we sample the model archived every 3 h closest 

to the time of satellite overpass for the SCIAMACHY and 

GOME products we use in Fig. I (10:00-10:30 local time). 

Trends in VCDtrop N02 are similar to those in NOx emissions (orange lines versus red triangles in Fig. 1 a-b), indicating that any changes in NOx chemical lifetime or partitioning have negligible influence in our modeL consistent with 

NOz loss against OH being minor during the morning overpasses of GOME and SCIAMACHY. The emission inventory 

used in BASE, from Lamarque et al. (2010) with annual interpolation after 2000 to RCP8.5 (Lamarque et al., 2012), 

mimics the opposing changes in NOx emissions over eastem China versus the EUS during 1996-2011, consistent with 

Atmos. Chern. Phys., 17,2943-2970,2017 
41 

2946 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

Table 1. Summary of forcings and emissions used in AM3 hindcasts and CM3 projections. 

Experiment Time periods Meteorology Radiative forcings CH4 (chemistry) Anthropogenic emissions Fire emissions 

BASE 

Background 

1979-2014 Nudged to NCEP Historical Historical Historical Historical 

1979-2014 As BASE Historical Historical Zeroed out inN, America; Historical 

FIXEMIS 

IAVFIRE 

!AVASIA 

1979-2014 As BASE 

1979-2014 As BASE 

1979-20122 As BASE 

IAVCH4 1979-20122 

CM3_RCP4.5 2005-2050 

CM3_RCP8.5 2005-2050 

As BASE 

Free running 

Free running 

Historical 

Historical 

Historical 

Historical 

RCP4.5 

RCP8.5 

2000 

2000 

2000 

Historical 

RCP4.5 

RCP8.5 

as in BASE elsewhere 

Constant1 Constant1 

Constant 1 Historical 

Varying in Asia as in BASE; Constant 1 

as in FIXEMIS elsewhere 

Constant1 

RCP4.5 

RCP8.5 

Constant 1 

RCP4.5 

RCP8.5 

I Averaged over the whole 1970-2010period. 2 Note !hat the IAVASIA and IAVCH4 ~1mulanoo~ only ex!end !O 2012 

3·

0 as em j 2.5 

s 

~ 

l 

.

. ~_~ - 1990 2000 2010 2020 2030 2040 2050 

!3.0arn ' 

z 25 Western US cities (satellites) 

6 g' 2.0 

• 1.5 d 1.0~-''"-'~!ii.. 

0.5 ·.· ............................ . 0

·£980 1990 2000 2010 2020 2030 2040 2050 

Year 

Figure 1. Changes in NOx emissions. (a-b) Mean annual vertical column densities of tropospheric (VCDtrop) N02 normalized to the year 

2000 for the eastern China and eastern US domains (black boxes on map) from GOME (1996-2002, open circles) and SCIAMACHY (2003-

201 I. closed circles) measurements and AM3 BASE simulations (orange lines). Triangles indicate trends in NOx emissions (normalized to 

2000) from Lamarque et al. (2010) with annual interpolation after 2000 to RCP8.5 (red) versus RCP4.5 (blue}. (c-d) Differences in annual 

mean SCIAMACHY VCDtrop N02 from 2003-2005 to 2009-2011. The red boxes denote the regions where emissions vary over time in the 

IAVASIA simulation (Table l). Satellite NOz data are from www.temis.nl, with the retrieval technique described in Boersma et aL (2004). 

changes in VCDtrop N02 retrieved from the satellite instruments. For comparison, the RCP4.5 interpolation for 2001-

2010 in CMIP5 historical simulations analyzed by Parrish et 

al. (20 14) underestimates the increase in Chinese NOx emissions by a factor of 2 (Fig. !a). Recent reduc1ions in Chinese 

NOx emissions after 2011 (Duncan eta!.. 2016) are not represented in the inventories used in AM3. 

Our BASE model applies interannually varying mon1hly 

mean emissions from biomass burning based on the RETRO 

inven!ory (Schultz et a!., 2008) for 1970 to 1996 and 

GFEDv3 (van der Werf eta!., 2010) for 1997 onwards. distributed vertically as recommend by Dentener et a!. (2006). 

Atrnos. Chern. Phys., 17, 2943-2970,2017 

Figure S2 illustrates the interannual variabitity of biomass 

burning CO emissions from the main source regions of the 

Northern Hemisphere over the period 1980-2014. Boreal 

fire emissions in Eurasia almost doubled from 1980-1995 to 

1996-2014, with large fires occurring more frcquenlly in the 

recent decade, as found for the WUS (Dennison eta!., 2014; 

Yang et al.. 2015). 

2.3 Ozone observation records and uncertainties 

Long-term surface 03 observation records were obtained at 

70 selec1ed rural monitoring sites with 20 (1995-2014) to 

27 (1988-2014) years of continuous hourly measurements 

www.atrnos-chern·phys.net/17/2943/2017/ 
42 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2947 

lbl YEl408 (JJ Ai 65n~OA2:t0.30pplrlyr',po.O.a 

/ol!I!0:0.2Bt0.27ppbvyr1,p•II.Ol 

40 

35 1990 2000 

Year 

2010 

Year 

(C) ROM406 IMAM} 

£5 /1!90:0,43tl).llppbvyF',p>rll. 

/Ol~0.2~0.17ppbvyr ,P"It 

-" ~55 ~···· • • • 

0 so • 

~ 045 

~ . 40 • 

35 1990 2000 

Year 

2010 

Figure 2. Measurement uncertainties. (a) Comparison of observed 

monthly mean MDA8 03 at WUS CASTNet siles. All sites have 

more than 90% data availability in every month shown. The gray 

shading denotes the period when data .at Yellowstone (red) and 

Rocky Mountain (black) were inconsistent with the other sites. (be) The 1990-2010 trends of median JJA MDAS 03 at Yellowstone 

and median MAM MDA8 03 at Rocky Mountain with and without 

data in 1990. 

from the US National Park Services, the US Clean Air Status and Trends Network (CASTNet), and the US EPA Air 

Quality System. Cooperet al. (2012) reported trends in daytime (II :00--16:00) 03 over 1990--2010 at 53 rural sites. We 

investigate trends in daily maximum 8 h averaged (MDA8) 

o, and expand the analysis of Cooper et al. (20 12) using additional data to 2014 and including 17 additional sites with 

measurements begun in 1991-1995. All sites have at least 

20 years of data. If a site has less than 50% data availability 

in any season, then that particular season is discarded. The 

trend is calculated separately for the 5th, 50th and 95th percentiles of daily MDA8 03 for each season through ordinary 

linear least-square regression. Statistics are derived for the 

slope of the linear regression in units of ppb yr- 1• the range 

of the slope with a 95% confidence limit (not adjusted for 

sample autocorrelation), and the p value indicating the statistical significance of the trend based on a two-tailed t test. 

A cross-site consistency analysis was perfonned to determine robust changes in the time evolution of 03 over the 

WUS during 1988-2014 (Fig. 2). The monitor at Yellowstone National Park was moved 1.5 km from the Lake Yellowstone site to the Water Tank site in 1996. While the local 

transport patterns are slightly different for the two sites, using 

MDA8 data from the well-mixed midday period minimizes 

the differences (Jaffe and Ray, 2007). Observed 0 3 interannual variations show large-scale similarity across sites over 

www.atmos-chem·phys.net/17/2943/2017/ 

the Intermountain West except for the earlier period 1989-

1990. During this period, observations at Yellowstone and 

Rocky Mountain national parks show low-03 anomalies that 

do not appear at other sites, but there is no change in measurement technique. Jaffe and Ray (2007) suggest this represents large-scale variations in background 03 that are seen 

in common at these two parks. However, analysis of meteorological fields and model diagnostics does not reveal any 

obvious transport anomaly influencing 03 variations at these 

sites in 1990 (Lin et a!., 20 15a). Observations at Pinedale 

in January-February 1990 are also anomalously low relative to Grand Canyon (GRC474), Centennial (CNT!69), and 

Gothic (GTH 161). These anomalous data at the beginning of 

measurement records can substantially influence trends calculated from short records. For example, Cooperet aL (2012) 

found a summer 0 3 increase of 0.42 ± 0.30 ppb yc 1 at Yellowstone over 1990-2010. Removing 1990. we find a weaker 

increase of0.28 ± 0.27 ppb yr- 1 (Fig. 2b). Removing 1990 at 

Rocky Mountain resulted in a weaker springtime 03 increase 

of 0.29 ± 0.17 ppb yr- 1 compared to 0.43 ± 0.23 ppb yr- 1 

over 1990-2010 (Fig. 2c). To assess robust o, changes, 

we thus remove these apparently uncertain measurements in 

1990 from the subsequent analysis. 

2.4 Model baseline sampling approach 

Springtime 03 observations at WUS high-elevation sites 

(2:: 1.5 km a.s.l.) typically represent baseline conditions with 

little influence from fresh local pollution. In a global model 

with "'200 x 200 km2 horizontal resolution, however, these 

remote sites can reside in the same grid cell that contains 

urban cities where NOx emissions decreased over the analysis period. For example, Rocky Mountain National Park 

(2. 7 km a.s. L) is less than l 00 km from the Denver metropolitan area in Colorado. This limitation of large-scale models in 

resolving urban-to-rural gradients and sharp topography results in an artificial offset of increased baseline 03 at remote 

sites by decreased urban pollution within the same model 

grid cell. Thus, coarse-resolution models are often unable to 

reproduce observed 03 increases at the high-elevation sites 

representative of remote baseline conditions (Fig. 3a versus 

b), as found in many prior modeling analyses (e.g., Parrish et 

al., 2014; Strode et al., 2015, and references therein). This 

limitation can be addressed by using a baseline selection 

procedure to identify conditions for sampling the model to 

avoid model artifacts caused by poor spatial resolution, as 

described below. 

All measurements presented in this study arc unfiltered. 

We implement a set of regional CO-like tracers (COt), with 

a 50-day exponential decay lifetime and surface emissions 

constant in time from each of four northern mid-latitude 

source regions (Lin et aL, 2014). We use these COt trac· 

ers to bin modeled o, according to the dominant influence of different continental air regimes. To represent observed baseline conditions at WUS sites, we sample AM3 

Atmos. Chern. Phys., 17,2943-2970,2017 
43 

2948 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

(a) Observed (b)BASESfc (c) BASE 700hPa filtered 

Figure 3. Influence of baseline sampling. rvtedian spring MDA8 

0 3 trends over 1988-2014 at WUS sites from (a) observations, 

(b) BASE model sampled at the surface, (c) BASE sampled at 

700 hPa and filtered to remove the influence from fresh local pollution (see Sect. 2.4), (d) BASE sampled at 700hPa without filtering, and (e-O Background (with North American anthropogenic 

emissions shut off) sampled at the surface versus at 700 hPa. Note 

that three low-elevation ( < 1.5 km) sites, Joshua Tree, Big Bend and 

Glacier national parks, are always sampled at the surface. Larger 

circles indicate sites with statistically significant trends (p<0.05). 

at 700hPa (~ 3 kma.s.l.) and filter the 03 data in the BASE 

simulation to remove the influence from fresh local pollution. Specifically, our filter excludes days when North American COt (NACOt) exceeds the 67th percentile for each season. This procedure yields higher calculated baseline 03 increases (Fig. 3c), bringing it closer to observations (Fig. 3a). 

When sampled at 700 hPa without filtering (Fig. 3d), BASE 

gives statistically significant 03 increases, but the rate of 

increase is ~ O.l ppb yr-• weaker than with filtering. With 

North American anthropogenic emissions shut off, the model 

simulates significant 03 increases that are similar at the surface (Fig. 3e) and at 700hPa (Fig. 31). This finding indicates that the underestimate of 03 increa'ies in BASE, when 

sampled at the surface (Fig. 3b), reflects an excessive offset 

from domestic pollution decreases in the model relative to 

observed conditions. as opposed to the insufficient mixing of 

free tropospheric 03 to the surface. As individual sites display observed trends falling in between the filtered model, 

and those sampled at the surface versus aloft, we can use 

the model to interpret which sites most frequently sample 

baseline versus being influenced by North American anthro~ 

pogenic emissions. For consistency, in the subsequent analysis we apply model baseline filtering to all WUS sites with 

elevations greater than l.5 km altitude. In the BUS, where 

the terrain and monitor elevations are much lower than in 

Atmos. Chern. Pbys., 17,2943-2970,2017 

the west and observed 03 trends are largely controlled by regional emission changes, we always sample the model at the 

surface without filtering. 

3 Global distribution of lower tropospheric 03 trends 

3.1 Global 03 burden and distribution of trends 

We begin by examining the global distribution of lower tropospheric 03 trends over 1988-2014 from the BASE simulation (Fig. 4) and focus on the differences between the 

surface and free troposphere ("' 700 hPa), with implications 

for understanding the impact of trend-; in hemispheric baseline 03 on surface air quality. The model indicates that surface MDA8 0 3 levels in Asia have increased significantly by 

1.5-2.5 ppb yr- 1 in the 95th percentile (Fig. 4a-b) and by 1-

2 ppb yr- 1 in the median values (Fig. 4c-d), with the largest 

increases occurring in southern Asia during spring and over 

eastern China during summer. In contrast, there is a marked 

decrease in surface MDA8 03 in WUS cities, throughout 

the EUS and in central Europe, particularly at the high percentiles and during summer. The increase in surface 03 over 

Asia and decreases over the US and Europe are consistent 

with changes in regional emissions of 03 precursors over this 

period (Fig. I). 

Over Southeast Asia (south of 30° N) during spring, earlier springtime 03 photochemical production at lower latitudes coupled with active frontal transport (Liu et al., 2002; 

Carmichael et al., 2003; Lin et al., 20 I 0) leads to a compa· 

rable or even greater increase in 03 in the free troposphere 

than at the surface (Fig. 4c versus e). In contrast, over central eastern China during summer the simulated trends of 03 

in the free troposphere are at least a factor of 3 weaker than 

in surface air (Fig. 4d versus t), consistent with the analysis 

of MOZAIC aircraft data over Beijing in 1995-1999 versus 

2003-2005 (Ding et al., 2008). Mean 03 at 700 hPa above 

parts of North America and Europe show little change in 

summer or even increase during spring in the model, similar to the trends at 500 hPa (Fig. S3), despite !he significant decreases in surface air. The global tropospheric 03 

burden in the BASE simulation increases by approximately 

30 Tg over the past 35 years (Fig. 5a), attributed mainly to 

changes in anthropogenic emissions. Over the 2004--20 IS 

OMJ/MLS satellite era, however, meteorological variability 

contributes approximately half to the total simulated decadal 

trends of 03 burden (Fig. 5a), indicating that attribution of 

the satellite-derived decadal trends of global tropospheric 03 

burden requires consideration of internal climate variability. 

3.2 Comparison of observed and simulated 03 trends 

in Asia 

Long-term 03 observations are very sparse in Asia, mak~ 

ing it difficult to evaluate modeled 03 trends. We compile 

available measurements from the published literature, indudwww,atmos-cbem-pbys.net/17/2943/2017/ 
44 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2949 

SO'N 

30'N 

o• 

30'S 

60"N 

30'N 

o• 

30'S 

60'S 

60'N 

30"'N 

0' 

30'S 

SO"S 

o• 90'E 

SO'N 

30'N 

o· 

30'S 

60'S 

60'N 

30'N 

o• 

30'S 

so•s 

60'N 

30'N 

o· 

30'S 

SO'S 

o• o• 90"E 180° 90°W 0" 

11111!1!!111!!1!1111!!~~~ ·0.8 ·0.6 ·0.4 ·0.2 0 0.2 0.4 0.6 0.8 [ppbyr'l ·0.8 ·0.6 ·0.4 -0.2 o 0.2 0.4 0.6 0.8 [ppb yr'J 

Figure 4. Global distribution of MDA8 0:3 trends from AM3 BASE over 1988-2014 for boreal spring (left) and summer (right) for the 

95th percentile at the surface (a-b), median at the surface (c-d), and median in the free troposphere (700 hPa; e-0. Stippling indicates areas 

where the trend is statistically significant (p <0.05). The color scale is designed to resolve regional features rather than extreme values and 

saturates. The range of the trends is -1 to +2.5 ppb yr-l. 

ing ozonesonde profiles at Hong Kong (2000-2014; www. 

woudc.org) and Hanoi (2005-2015; SHADOZ, Thompson 

ct al., 2007), MOZAIC aircraft profiles collected on sum· 

mer afternoons in the boundary layer (below 1250 m alti· 

tude) over Beijing for 1995-2005 (Ding et al., 2008), ground· 

based measurements at Mt. Tai (l.5 km a.s.l.) in central eastem China for July-August 2003-2015 (Sun et al., 2016), at 

the GAW stations, Shangdianzi north of Beijing for 2004-

2014 (Ma et al., 2016) and Mt. Waliguan (3.8kma.s.l.) on 

the Tibetan Plateau for 1994-2013 (Xu et al., 2016), at Tai· 

wan for 1994-2007 (Lin et al., 20 I 0). South Korea for 1990-

2010 (Lee et al., 2014). Mt. Happo (1.9kma.s.l.) in Japan 

for 1991-2011 (Tanimoto, 2009; Parrish et al., 2014), and a 

coastal site at Hong Kong in southern China for 1994-2007 

(Wang et al., 2009). 

Recently, Zhang et al. (2016) compiled sparse 03 profiles 

above Southeast Asia from lAGOS commercial aircraft and 

ozonesondes from Hanoi for 1994-2004 versus 2005-2014 

and found a total springtime o, increase of 20-25 ppb be· 

tween the two periods (~2ppbyC ). However. our model 

indicates an increase of up to I ppb yc 1 for free tropo· 

spheric 03 over Southeast Asia in spring (Fig. 4e). We illuswww.atmos-chem-phys.net/l7/2943/2017/ 

trate the possible influence of sampling deficiencies on the 

03 trends inferred from sparse observations (Fig. 5). The 

ozonesonde frequency is four profiles per month at Hong 

Kong and only one to two profiles per month at Hanoi. To 

determine the representativeness of 03 trends derived from 

these sparse measurements, we compare observations and 

model results co-sampled on sonde launch days, with the 

"true average" determined from 03 fields archived every 3 h 

from the model, as in our prior work for WUS sites (Lin 

et al., 20!5a, b). Figure 5b and c show the comparisons 

for the annual trends of 03 over 900..{;00 hPa. The trends 

are generally consistent across the sonde data, model cosampled and ''true average" results for Hong Kong, with 

an increase of 0.5 ± 0.1 ppb yr- 1 over 2000-2014. Observations at Hanoi show an apparently rapid 03 increase of 

!.I± 0.2 ppb yr- 1 over 2005-2014. AM3 BASE. when sam· 

pled sparsely as in the ozonesondes, captures the observed 

variability (r2 =0.7), whereas the "true average" over this 

period indicates the trend (0.7 ± 0.1 ppb yr- 1) is only 63% 

of that inferred from observations. Moreover, interannual 

variability of O:l resulting from wildfire emissions and me· 

teorology in IAVFIRE is as large as the total O:l change in 

Atmos. Chern. Phys., 17,2943-2970, 2017 
45 

2950 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

t: 

~ 

~ 

"E 

il 

0 

ci. 

2 

f-

(a) Changes in global trop. 0 3 burden 

30 BASE 

. FIXEMIS 

20 

-10 

1960 

10 :; Hong Kong (22.3"N,114.2"E, 900-600 hPa) 

BASE eo-sampled 

tAVf'lRE BASE true average 

10 oss {c) ~:::~!~~.:~N,105.8"E, 900-600 hPa) 

!AVf'!RE BASE true average 

2005 2010 2015 

Figure 5. (a) Time series of changes in global tropospheric 03 bur~ 

den relative to the 1981-1990 mean from BASE and FlXEMIS 

simulations (Table l), (b) Time series of 12-month running mean 

anomalies (relative to the 2005-2014 mean) of 03 averaged over 

900-600 hPa at Hong Kong from the averages of ozonesonde samples (black circles) and the BASE model co~sampled on sonde 

launch days (orange circles) versus the true average from BASE and 

IAVFIRE with continuous daily sampling (solid lines). (c) Same as 

(b), but for Hanoi. 

BASE over the short period 2005-2014. We conclude that 

measurement sampling artifacts influence the OJ trends reported by Zhang et al. (20!6). 

Expanding the comparison to a suite of sites across East 

Asia (Fig. 6), we find that AM3 captures the key features 

of observed 03 trends in Asia, including their seasonal to 

regional variations, summertime increases ( 1-2 ppb yr- t) in 

central eastern China where NOx emissions have approxiAtmos, Chern. Phys., 17,2943-2970,2017 

75"E 90°E 105°E 120"E t35"E 150"E 

·2 -1.6 -1.2 -0.8 .• } .• :.; .. 0.8 1.2 1.6 2 [ppb y('] 

(b) 3.5~-------------~ [JOSS .Gf0l-AM3 

3.0 

0.5 

0·0 ~.Ta1 JA 

Figure 6. Surface 03 trends in Asia. (a) Observation sites superimposed on a map of the 95th percentile summer MDA8 03 trends 

over 1995-2014 from AM3 BASE. (b) Comparison of median 03 

trends from AM3 (1995-2014) with observations (see text for pe~ 

riods): in central eastern China at Mt. Tai (July-August, Sun et aL, 

2016), Beijing (May-June-July, Ding et al., 2008) and Shangdianzi 

(SDZ) (JJA, Ma eta!., 2016); in South China at Hong Kong (HK) 

(annual average, Wang et al.. 2009) and Taiwan (MAM, Lin et al., 

2010); at Mt Waliguan (WLG) in western China (MAM, Xu et aL, 

2016); in South Korea (JJA, Lee eta!., 2014) and Mt. Happo Japan 

(MAM, Tanimoto, 2009). For Mt. Happo (triangle on map) AM3 is 

sampled at 700 hPa and filtered for the influence from Asian comi~ 

nental air- more representative of observed baseline conditions in 

spring. 

mately tripled since l990 (Fig. la), and springtime increases 

(0.5ppbyr- 1) at Taiwan and Mt. Happo that are driven by 

pollution outflow from the Asian continenL Note that to place 

the trends derived from the short observational records into 

a broader context, we show the 20-year trends over 1995-

2014 from the model, except for South Korea (!990-20!0) 

and Happo, Japan (!991-201!). We match the time period in 

the model with observations at these two sites because AM3 

shows weaker 03 increases when data for the recent years 

arc included, which likely reflects the offsetting effects of regional emission reductions in South Korea and Japan. 

www.atmos-chem-phys.net/17/2943/20 17/ 
46 

M. Lin et al.: VS surface ozone trends and extremes from 1980 to 2014 2951 

Observed BASE 

(f) 

,~~ ppb yr' 

·0.8 -0,6 -0,4 -0.2 0.0 0.2 0,4 0.6 0,8 

Figure 7. Linear trends in spring (MAM) MDA8 03 over 1988-2014 at US rural sites for the 95th, 50th, and 5th percentiles as observed 

(left) and simulated (right) in AM3 BASE. Larger circles indicate sites with statistically significant trends (p <0.05). For WUS high~elevation 

sites, the model is sampled at 700hPa and filtered to remove local influence (see rext in Sect 2.4). 

Parrish et al. (2014) show that three CMIP5-like models 

underestimate the observed springtime 03 increase at Mt. 

Happo by a factor of 4. This discrepancy may reftect a combination of factors: ( l) underestimates of Asian emission 

growth in the RCP4.5 interpolation after 2000 used in CMIP5 

historical simulations (Fig. la); (2) trends driven by interannual meteorological variability that free-running CMIP5 

models are not expected to reproduce exactly; (3) an excessive offset from Japanese pollution decreases in the models owing to their coarse resolution and limitation in resolving observed baseline conditions at ML Happo. Sampling our BASE model at 700 hPa above Happo. we find an 

03 increase of0.35 ±0.13 ppbyc1. When focusing on days 

strongly influenced by outflow from the East Asian continent (Chinese COt::, 67th), the model 03 trend increases to 

0.48 ± 0.13 ppb yr-t, approximating the observed increase 

of0.76±0.35ppbyr- 1 atMt. Happo(Fig. 6b). The observed 

and simulated trends are not statistically different given the 

overlapping confidence limits. The larger confidence limit 

www.atmos-chem-phys.net/17/2943/2017/ 

(uncertainty) derived from the Happe observations reflects 

the measurement inconsistency before 1998 and instrumental problems after 2007 (Tanimoto et al., 2016). We conclude 

that GFDL-AM3 captures 65-90% of the observed o, increases in Asia, lending confidence in its application to assess the global impacts of rising Asian emissions. 

4 Regional and seasonal variability of US surface 03 

trends 

We next focus our analysis on the lJS, where dense, highfrequency, long-term, reliable measurements of surface 03 

facilitate process-oriented model evaluation. Comparisons of 

surface 03 trends over 1988-2014 at 70 rural monitoring 

sites across the US as observed and simulated in AM3 BASE 

are shown in Fig. 7 for spring, Fig. 8 for summer, Fig. 9 for 

winter, and in Fig. S4 for autumn. The trends are calculated 

separately for the 5th, 50th and 95th percentiles of the daily 

MDA8 03 concentration distribution. with larger circles on 

Atmos. Chern. Phys., 17,2943--2970,2017 
47 

2952 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

Observed BASE 

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 

Figure 8. As in Fig. 7, but for summer (JJA). Note that the color scale saturates at ±0.8. 

the maps indicating sites with statistically significant trends 

(p < 0.05). We first discuss observations (Sect. 4.1). followed 

by model evaluation and trend attribution (Sect. 4.2). 

4.1 Observations 

ln spring (Fig. 7), observations indicate spatial heterogeneity 

in 03 trends across the Intermountain West and the north~ 

eastern (north of 38' N) and southeastern US. At the 95th 

percentile (Fig. 7a) the pattern of observed trends is homogeneous across the northeastern and southeastern US, with 

approximately 85 % of the sites having statistically significant 03 decreases of 0.4-0.8 ppb yr- 1 and no sites showing a 

significant increase. In contrast, significant increases occur at 

25% of the sites in the Intermountain West. Only Joshua Tree 

National Park located downwind of the Los Angeles Basin 

shows a significant decrease at the 95th percentile. At the 

50th percentile (Fig. 7b) there are significant 03 decreases of 

0.2-0.4 ppb yr- 1 in the southeast and little overall change in 

the northeast, while significant increases of 0.2-0.5 ppb yr-t 

occur at 50% of the sites in the Intermountain West. Significant springtime 03 increases occur at all observed perAtmos. Chern. Pbys., 17,2943-2970,2017 

centiles at Lassen Volcanic National Park in California, Great 

Basin National Park in Nevada, Rocky Mountain National 

Park and US Air Force Academy in Colorado. At the 5th percentile (Fig. 7 c) significant 03 increases occur at most sites 

in the northeast, while little change and some negative trends 

are found in the southeast. The occurrence of the greatest 

observed 03 decreases for the highest percentiles is consistent with high-temperature 03 production being more NOxlimited (Pusede et al., 2015) and thus more responsive to decreao:;es in NOx emissions. 

The north-to-south gradient in springtime 03 trends over 

the EUS reflects the earlier seasonal transition from NO,rsaturated to NOx-sensitive 03 production regimes in the 

southeast, where plentiful radiation in spring enhances HOx 

supply and biogenic isoprene emissions begin earlier than 

in the northeast. The different response of springtime 03 to 

NOx controls in the southeast versus northea'it noticed in this 

work is not present in prior analyses for shorter time periods (1990-2010 in Cooper et al.. 2012, and 1998-2013 in 

Simon et al., 2015). We find 72% of the southeastern sites 

experiencing significant median 03 decreases in spring over 

www.atmos-cbem-pbys.net/17/2943/2017/ 
48 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2953 

Observed BASE 

Figure 9. As in Fig. 7, but for winter (DJF). Large squares in (a) denote AQS sites with significant 03 decreases in the 95th percentile. 

1988-2014, while Cooper et aL (20 12) found only 8 %. Sites 

with significant 95th percentile springtime 03 decreases in 

the EUS are also much more common in our study (85% 

versus 43% in Cooper et aL (2012). In the 5th percentile, 

45% of the northeastern sites in our analysis have significant 

spring o, increases, with only 15% in Cooper eta!. (2012) 

Stronger 03 reductions in the southeast than the northeast 

also occur during autumn (Fig. S4), reflecting an extension 

of biogenic isoprene emissions and NOx-sensitive 03 production in the southeast to autumn. 

In summer (Fig. 8), as radiation intensifies and isoprene 

emissions peak seasonally, the 03 production becomes more 

NO,t-limited across both the southeastern and northeastern 

US, where NOx emission controls have led to significant 

03 decreases of 0.8-1.8 ppb yr-t in the 95th percentile and 

0.4-{).8ppbyr-1 in the median value (Fig. Sa-b). In the 

southeast, significant decreases have also occurred at the 

lowest percentiles during summer (Fig. 8c), in contrast to 

the weak response during spring (Fig. 7c). Many northeastem states in the late 1990s and early 2000s did not tum 

on power plant NOx emission controls until the 03 season 

www.atmos-chem-phys.net/17/2943/2017/ 

(May-September), which may contribute to observed differences between spring and summer 03 trends. Compared 

to the 1990-2010 trends reported in Cooper eta!. (2012), 

the EUS summer 03 decreases reported here with additional 

data to 2014 are 33% stronger. Despite reductions in precursor emissions in the WUS cities (Fig. ld), there are no 

significant summer 03 decreases at the intermountain sites, 

except in Yosemite and Joshua Tree national parks for the 

95th percentile. InsLead, a significant summer increase of 

""'0.3 ppb yr- 1 occurs across the entire 03 distribution at Yellowstone. Significant summer increases are found in the 5th 

percentile for Lassen, Mesa Verde, and Rocky Mountain national parks. 

In winter (Fig. 9), observed 03 increases are more common than in spring and summer across the US. The wintertime 03 increases are strongest in the lowest percentiles 

over the EUS, indicating the influence from weakened NOx 

titration as a result of regional NOx emission controls (see 

also Gao et a!., 20!3; Clifton et a!., 2014; Simon et a!., 

2015). Even during winter, some decreasing 03 trends are 

found in the highest percentiles over the southeast (Fig. 9a). 

Atmos. Chern. Phys., 17, 2943-2970, 2017 
49 

2954 M. Lin et al.: t:S surface ozone trends and extremes from 1980 to 2014 

most prominently in Texas (Dallas and Houston), where tropical climate and year-round active photochemistry makes 03 

most responsive to regional NOx emission controls. Despite 

the greatest NOx emission reductions over the past decade in 

the central and northeastern US regions, observed 03 reductions have.been most pronounced in the southeast, particularly in spring and autumn. 

4.2 Model evaluation and attribution of observed 03 

trends 

The BASE simulation with GFDL-AM3 captures the salient 

features of observed 03 trends over 1988-2014 at rural sites 

across the US: (l) the overall springtime increases and the 

lack of significant trends in summer over the Intermountain 

West; (2) the north-to-south gradients in 03 trends during 

spring and the largest decreases in the 95th percentile during summer over the EUS; (3) wintertime increases in the 

5th and 50th percentiles (left versus right panels in Figs. 7 to 

9). AM3 also simulates a median springtime 03 increase of 

0.32±0.11 ppbyr- 1 over 1988-2014 (0.64±0.50ppbyr- 1 

over 2004-2014) at Mount Bachelor Observatory in Oregon, consistent with the positive trend (0.63 ± 0.41 ppb yr- 1) 

observed over the shorter 2004--2015 period (Gratz et al., 

2014). These analyses imply that GFDL-AM3 represents the 

underlying chemical and physical processes controlling the 

response of US surface 03 means and extremes to changes in 

global-to-regional precursor emissions and climate, despite 

mean state biases (Figs. S5-S6). 

The filtered model shows greater 95th percentile 03 increases than observed at some WUS sites (e.g., Yosemite: 

Grand Canyon; Canyonlands) for both spring and summer 

(Figs. 7a, d and Sa, d), reflecting that observations at these 

sites sometimes can be influenced by transport of photochemically aged plumes from nearby urban areas and from 

southern California during late spring and summer. When 

sampled at the surface, AM3 simulates small summertime 

03 decreases in the 95th and 50th percentiles over the Intermountain West (Fig. 4b, d), consistent with observations at 

Yosemite, Grand Canyon, and Canyonlands (Fig. Sa, b). As 

illustrated in Pig. 3 for spring and discussed in Sect. 2.4, individual sites in the west display observed trends falling in 

between the filtered model and those sampled at the surface 

versus aloft 

We examine how US surface 03 responds to changes in 

regional anthropogenic emissions, hemispheric background, 

and meteorology by comparing o, trends in the BASE, 

Background, and FIXEMIS experiments (Figs. lO-ll). With 

North American anthropogenic emissions shut off in the 

Background simulation, little difference is discernable from 

the BASE simulation for WUS 03 trends during spring 

(first versus second rows in Fig. 10), indicating the key role 

of hemispheric background driving increases in springtime 

03 over the WUS. With anthropogenic emissions held constant in time, FIXEMIS still shows statistically significant 

Atmos. Chern. Pbys., 17,2943-2970,2017 

spring 03 increases in the 95th percentile (Fig. JOe). approximately half of the trends simulated in BASE, for Grand 

Canyon, Canyonlands, Mesa Verde and Rocky Mountain national parks. Prior work shows that deep stratospheric intrusions contribute to the highest observed and simulated sur~ 

face 03 events at these sites (Langford et al., 2009; Lin et 

al., 2012a). Strong year-to-year variability of such intrusion 

events (Lin et al., 2015a) can confound the attribution of 

springtime 03 changes over the WUS to anthropogenic emission trends, particularly in the highest percentile and over 

a short record length. Summer avoids this confounding influence when stratospheric intrusions are at their seasonal 

minimum, as evidenced by little 03 change in FIXEMIS 

over the WUS (Fig. lie, f). In contrast to spring, the model 

shows larger differences in WUS 03 trends between BASE 

and Background for summer when North American pollution peaks seasonally (Fig. lOa, d versus b, e compared to 

Fig. lla, d versus b, e), There are significant increases of0.2-

0.5ppbyr-1 in the 95th and 50th percentile summer background 03 at more than 50% of the western sites (Fig. 11 b, 

e), offsetting the 03 decreases resulting from US NOx reductions and leading to little overall change in total observed and 

simulated 03 at WUS rural sites during summer (Fig. 8). 

Over the EUS, AM3 also simulates background 03 increases, occuning in both the 95th and 50th percentiles, with 

a rate of 0.1-0.3 ppb yc t during spring (Fig. lOb, e) and 

0.2-0.5 ppbyr- 1 during summer (Fig. llb, e). Based on prior 

model estimates that springtime background 03 is greater in 

the northeast than the southeast (Lin et al., 20 l2a, b; Fiore et 

al., 2014), one might assume that the springtime 03 increases 

in the 5th percentile observed over the northeast (Fig. 7c) 

have been influenced by a rising background. However, AM3 

simulates homogeneous background 03 trends across the entire EUS (Fig. lOb, e), indicating that the observed north-tosouth gradient in 03 trends reflects an earlier seasonal onset of NO.csensitive photochemistry in the southeast. as opposed to the background influence. 

A warming climate is most likely to worsen the highest o, events in polluted regions (e.g., Schnell et al., 2016; 

Shen et al., 20 16). With anthropogenic emissions held constant in time over 1988-2014, FIXEMIS suggests significant increases of0.2-0.4 ppb yr- 1 in the 95th percentile summertime 03 over the EUS (Fig. l1c), Using self-organizing 

map cluster analysis, Horton et al. (2015) identified robust 

increases in the occurrence of summer anticyclonic circulations over eastern North America since 1990. We find 

that biogenic isoprene emissions over this period increased 

significantly by l-2%yr- 1 (10 to 20mgcm-2 summer- 1) 

throughout the EUS in the model, consistent with simulated 

increases in the 90th percentile JJA daily maximum temperature (Fig. 12a-b ). Increases in isoprene emissions contribute 

to raising EUS background 03 in summer (Fig. llb, e). Using the Global Land-Based Datasets for Monitoring Climate 

Extremes (GHCNDEX; Donat et al., 20!3), we find increases 

in the number of warm days above the 90th percentile and 

www.atmos-chem-phys.net/1712943/20171 
50 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2955 

BASE BASE 

Background Background 

FIXEMIS FIXEMIS 

Figure 10. Linear trends in the 95th (left) and 50th (right) percentile springtime MDA8 03 over 1988-2014 at US rural sites from BASE 

(top), Background (middle) and FIXEMIS simulations (bottom). Larger circles indicate sites with statistically significant trends (p <0.05). 

Top panels are repeated from Fig. 7d, e. Note that the 95th (50th) percentile is sampled separately from the Background and FIXEMIS 

simulations without depending on the times when the BASE simulation is experiencing the 95th (50th) percentile days. 

maximum temperature over the southeastern US in August 

(Fig. 12c-d). The trends in temperature extremes are similar 

between June and August, but there is no significant trend in 

July (not shown). While changes in regional temperature ex~ 

tremes on 20- to 30-year time series may reflect internal climate variability (Shepherd. 2015), we suggest that increasing 

hot extremes and biogenic isoprene emissions over the last 

2 decades may have offset some of the benefits of regional 

NOx reductions in the EUS. 

www.atmos·chem·phys.net/17/2943/2017 I 

5 Impacts of rising Asian emissions, methane and 

wildfires on western US 03 

5.1 Historical western US 03 trends in spring 

Further indications of the factors driving baseline 03 

changes over the WUS can be inferred by examining the 

time series at several high-elevation sites, which most 

frequently sample baseline 03 in the free troposphere during 

spring (Sect. 2.4). Figure 13 shows the results, both observed 

and simulated, for six such monitoring sites: Great Basin 

National Park in Nevada (2.1 km a.s.l.), Rocky Mountain 

National Park (2.7 kma.s.l.) in Colorado, US Air Force 

Academy (1.9kma.s.l.) in.Colorado Springs. Yellowstone 

National Park (2.4kma.s.l.) and Pinedale (2.4krna.s.l.) in 

Wyoming, and Mesa Verde National Park (2.2 km a.s.l.) 

in the Colorado-New Mexico-Arizona-Utah four~comer 

Atmos. Chern. Phys., 17,2943-2970, 2017 
51 

2956 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

BASE BASE 

FIXEMIS FIXEMIS 

-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 

Figure 11. As in Fig. 10, but for summer. Top panels are repeated from Fig. 8d. e. 

region. The observed median values of springtime MDA8 

03 have increased significantly at a rate of 0.2-0.5 pph yr- 1 

over the past 20-27 years at these sites, except Pinedale, 

where the increase in background 03 is likely offset by the 

03 decrease due to recent emission control for the large oil 

and gas production fields in this area (http://deq.wyoming. 

gov/aqd/winter-ozone/resources/technical~documents/). 

When filtered to remove the influence from fresh local 

pollution (Sect. 2.4), AM3 BASE captures the long-term 

trends of 03 observed at these sites. 

Correlating AM3 Background with observed 03 indicates 

that most of the observed variability reflects changes in the 

background, with Huctuations in stratospheric influence con~ 

tributing to anomalies on interannual timescales (e.g., the 

1999 anomaly, Lin et al., 20 !Sa), whereas Asian influence 

dominates the decadal trends as discussed below. The 03 reduction resulting from US anthropogenic emission controls 

is less than 0.1 ppb yr- 1 (BASE minus Background) at these 

baseline sites. We show model results for the entire 1980-

Atmos. Chern. Phys., 17,2943-2970,2017 

2014 period for Great Basin, Rocky Mountain, and the US 

Air Force Academy to provide context for observed trends in 

the 2 most recent decades (Fig. 13a). In the 1980s when Chinese NOx emissions ('""' 4 Tg yr- 1 NO) were much lower than 

US NOx emissions(~ l5Tgyc 1 NO) (Granieret al., 2011), 

there was little overall 03 change over the WUS in the model. 

From the mid-1990s onwards, with NOx emissions in China 

rising steeply (Fig. Ia) and surpassing US emissions in the 

2000s, the 03 trends at remote WUS sites appear to be dominated by trends or background, reflecting rising emissions 

outside the US, The largest spring 03 increases from 1981-

1990 to 2003-2012 at 700 hPa extend from Southeast Asia 

to the subtropical North Pacific Ocean to the southwestern 

US (Fig. S7a), consistent with the influence of rising Asian 

precursor emissions. 

Table 2 contains a summary of the drivers of 03 trends 

in the model at seven CASTNet sites that exhibit a significant spring 03 increase observed over 1988-2012. Here we 

focus our attribution analysis on the period 1988-2012 (inwww.atmos·chem·phys.net/17/2943/2017/ 
52 

Un L'S surface trends and extremes from l9l:W 

www.atmos-ehem-phys.net/l7/294.V20 171 
53 

2958 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

(a) 15 GreatBaslnNP,NV[114"W,39"N,2060m] 

~!ie· ~.=~·.~~:,!~1'. ~-~ r(OBS.AJI3)'=0.6B 

(b) 15 r-o:=~v.,.e,.ll,..ow,.•,.t~o..,.ne_N..,P-''C,.WY:-:-:--i-[1_1r0.~4·_w....:.,.• 44....,...6"~N;.., 2~40....,-o..,m.:..] ~-, 

- 10 ·NAB OAO:t0.11ppbyr1,p..Q,OO r(OB$.A.M3)=6.11 g:~* ~]~~:~~ ~~ 'fr~. ~-.: 

i 

~ 

~ 

:g: 

s 

,.., 

~ g 

"' 0·10 

NAB 0.30:!:0.11 ppb YT"\ P""-0.00 

• 

~ 

• 15 l.o..c';"19;:;9::!0~~-::19!'::9::5~.ow.o:2:;';0:';::0~0 ~~2;';:0~05::-.uw.o;2::;0=:10~ 

Pinedale, WY [109.6" W, 42.9° N, 2388 m] 15 OBS 0.09±0.18 ppb yr\ P=0.318 

~ 10 ~A:~ ~~~~1~r;!J,~r;:{,~·~~ 

.;,. 

~ "' 

,.., 5 

~ g ~-~~~~ ~ 

0 "' ·10 0-10 . ~~~ ....................... .. •

1

rsao 11ls5 1silo 1995 2ooo 2oo5 2010 2o1s ' 15 '--'-c"19""9~0~~w19~9'::5~~2:'"0":'0~0~~2:"0':'05~-'-"-'~2:':"0":C10~ 

15us0

: F~=.:;.c::::;~·,:.o~1os•w, 39" N,1971m] BASE* 0.34:t0.14 ppb yr1, P.O.OO r (08S,AM3)=0.58 

:Q 1 Q NAB 0.43.!:0.15 ppb yr1, P..O.OO r (OBS,AM3)=6.~ 

~ e,.o 

"' i 

"' -5 

0 -10 

•

1

rsso 1985 19so 1995 "2ooo 2oo5 ·2o1o 2~15 

Year(MAM) 

' 15 L...c...,.:19'"'90:::-'-~~1;'::9:';::9~5~~2:':!0'::'00~~.o:2:::00:;:5~~-o:2~01:'!0~ 

Year(MAM) 

Figure 13. (a) Time series of median spring MDA8 03 anomalies (relative to the 1995-2014 mean) at Great Basin, Rocky Mountain, and US 

Air Force Academy a.<; observed (black) and simulated in AM3 BASE filtered for baseline conditions (red; see Sect. 2.4) and in Background 

with North American anthropogenic emissions zeroed out (NAB; green). Presented at the top of the graph are statistics from the linear fit 

and correlations between observations and simulations. Numbers at the bottom of the graph denote the sample size of observations for each 

year. Gray dots indicate uncertain observations that are removed from the linear fit (see Sect. 2.3).(b) Same as Fig. 13a, but for Yellowstone, 

Pinedale, and Mesa Verde over the period 1988-2012. 

With only methane varying. the model trends are Jess than 

0.1 ppb yr- 1 (lAVCH., minus FTXEMIS), accounting for an 

average of 15% of the background increase. The contribution from wildfire emissions during spring is of minor importance (IAVFIRE minus FIXEMIS, Table 2). A stratospheric 

03 tracer (03Strat) in AM3 (Lin eta!., 20 l2a, 20 l5a) demonstrates a positive but insignificant trend in stratospheric 03 

transport to the sites. We examine the trends of lower tropospheric 03 at these sites when transport conditions favor the 

import of Asian pollution into western North America, as diagnosed by the East Asian CO tracer (EACOt) exceeding the 

67th percentile for each spring. Similar to the conclusion of 

Lin et al. (20l5b), we find that the rate of 03 increase in the 

Background simulation is greater by 0.05-0.l ppb yr- 1 under strong transport from Asia than without filtering. FilterAtmos. Chern. Pbys., 17,2943-2970,2017 

ing the IAVASIA simulation for Asian influence also results 

in greater 03 increases than filtering for baseline conditions 

(Table 2). 

Rising Asian emissions even influence trends of 03 downwind of the Los Angeles Basin during spring. 03 measured in Joshua Tree National Park shows an increase of 

0.3l±0.25ppbyr-1 in spring over 1990-2010 (Cooper et 

al., 2012), despite significant improvements in 03 air quality in the Los Angeles Basin (Warneke et al., 2012). The 

03 record extended to 2014 shows a decline in the 95th percentile 03 in Joshua Tree National Park for both spring and 

summer (Figs. 7-8), whereas the 5th percentile continues to 

increase in spring and there is no significant trend in the median. Sampling the AM3 Background simulation at this site 

indicates a rising background (0,31 ±0.14 ppb yr- 1 ). Airwww.atmos·chem-pbys.net/17/2943/2017/ 
54 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2959 

15 OBS 

AM3_BASE 

10 

Western US (700 hPa. MAM} 

CM3_RtP8.5 

CM3_RCP4.5 

Year 

Figure 14. Future projections. Time series of median springtime 03 

changes relative to 2010 in GFDL At\13 hindcast (orange cirdes) 

and CM3 future simulations for RCP8.5 (red) versus RCP4.5 (blue; 

shading represents the range of three ensemble members), sampled 

at 700hPa over the WUS (35-45° N, l20-l05° W), Black circles 

indicate observed changes averaged from the La.'>Sen, Greal Basin, 

and Rocky Mountain national parks. 

craft measurements in May-June 20 I 0 indicate the presence 

of Asian pollution layers 2 km above southern California 

with distinct sulfate enhancements coincident with low organic mass (Lin et al., 2012b), supporting the conclusion 

that rising Asian emissions can contribute to trends of 03 observed in this region. Yosemite National Park (l.6kma.s.l.) 

and Chiricahua National Monument (l.5kma.s.l.) are also 

influenced by increases in Asian emissions and concurrent 

decreases in local pollution in California. 03 observed at 

Yosemite shows an increase from 1995 to around 2012 

(0.37 ± 0.32 ppb yr- 1; Fig. S8), which the model attributes 

primarily to rising Asian emissions (Table 2), but observations have remained constant since then, reflecting an offset 

by 03 decreases in California (Fig. 4). 

5.2 Projecting western US springtime 03 for the 21st 

Century 

Under the RCP8.5 scenario, Chinese NOx emissions are 

projected to peak in 2020-2030. reflecting an increase of 

-50% from 20!0 (Fig. la), followed by a sharp decrease, 

reaching 1990 levels by 2050. Global methane increases by 

-60% from 2010 to 2050 under RCP8.5 (Fig. Sl). Under 

the RCP4.5 scenario, in contrast, NOx emissions in China 

change little over 2010-2030 and global methane remains 

almost constant from 2010 to 2050. NOx emissions in the 

US decrease through 2050 under both scenarios, by -40% 

from 20 I 0. A number of studies have examined future US 

o, changes under the RCPs (e.g., Gao et al., 2013; CliHon 

et al., 2014; Pfister et al., 2014; Fiore et al., 2015; Barnes 

et a!., 20 16). However, as discussed earlier, the trends of 03 

in the model when sampled near the surface are overwhelmingly dominated by US anthropogenic emission trends. Thus, 

www.atmos-chem-phys.net/17/2943/2017/ 

8!AVASIA' CllAVASIAE 

.lAVCH4 .IAVF!RE 

0.8 FIXEMIS 

~~~d~ UJA) 

(b) 

Figure 15. Summertime 03 in Yellowstone National Park. (a) Median JJA MDA8 03 trends over 1988-2012 at Yellowstone from 

observations (black) and simulations sampled at 700 hPa for 

BASE without filtering (pink), BASE filtered for baseline conditions (hatched pink), IAVASIA (solid purple, baseline), IAVASIA filtered for Asian influence (EACOt 2:: 67th, hatched purple), 

lAVCH4 (cyan), IAVFIRE (orange) and FIXEMIS (red). (b) Time 

series of anomalies in August median MDA8 03 at Yellowstone as 

observed (black) and simulated by the model sampled at the surface, 

with constant (red) and time-varying wildfire emissions (orange). 

Trends over 1988-2014 are reported. {c) Interannual correlations of 

JJA mean MDA8 03 observed at Yellowstone with JJA mean daily 

maximum temperature from observations (Harris et al., 20 14). 

the future 03 changes estimated by these prior studies do not 

represent baseline conditions, particularly the response to rising Asian emissions. In Fig. 14 we show changes in WUS 

free tropospheric (700hPa) 03 relative to 2010 in the CM3 

future simulations under RCP8.5 versus RCP4.5. Historical 

hindcasts and observations are also shown for context. Under RCP4.5, springtime 03 over the WUS shows little overall 

change over 2010-2050. Under RCP8.5, in contrast, springtime WUS o, increases by- !Oppb from 2010 to 2030 and 

remains almost constant from 2030 to 2050, consistent with 

the projected trends in Asian emissions and global methane. 

5.3 Trends and variability of western US 03 in summer 

Yellowstone National Park is the only site with statistically 

significant summer 03 increases observed across all percenliles (Fig. 8a-c). The 1988-2012 trends for the median 

observed and simulated 03 are summarized in Fig. 15a. Observations show an increase of 0.32 ± 0.18 ppb yr- 1 for JJA, 

with a greater rate of increase in June (0.38 ± 0.25 ppb yr- 1) 

than in July-August (0.26±0.18ppbyr- 1). AM3 BASE 

sampled at 700 hPa and filtered for baseline conditions 

(hatched pink bar in Fig. l5a) captures the observed increase. 

Without baseline filtering (solid pink bar), North American emission reductions offset almost 50% of the simulated 

Atmos. Chern. Phys., 17,2943-2970, 2017 
55 

2960 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

03 increase at Yellowstone, causing the model to underestimate the observed 03 trend. The model attributes much of 

the observed summer 03 increase at Yellowstone to rising 

Asian emissions, with lA VASTA simulating an 0 3 increase 

of 0.31 ± 0.19 ppb yr-1 under baseline conditions, increasing 

to 0.42 ± 0.23 ppb yr- 1 under conditions of Asian inftuence 

(EACOt 2: 67th percentile). The stronger increase measured 

in June than in July~August is consistent with the influence 

of the Asian summer monsoon producing a surface 03 minimum in July-August in East Asia (e.g., Lin et al., 2009), 

as well as the seasonality of intercontinental pollution transport. Changes in methane, wildfires, and meteorology over 

this period are of minor importance for the JJA 03 trends at 

Yellowstone. 

Enhanced wildfire activity in hot and dry weather is 

thought to be a key driver of interannual variability of surface 03 in the Intermountain West in summer (Jaffe et aJ., 

2008; Jaffe. 2011 ). However, hot and dry conditions also 

facilitate the buildup of o, produced from regional anthropogenic emissions, which can complicate the unambiguous 

attribution of observed 03 enhancements. Using August data 

at Yellowstone as an example, we isolate the relative contri~ 

bution of these two processes to observed 03 with the lAYFIRE versus FIXEMIS experiments (Fig. 15b). Here we sample AM3 at the surface to account for any inllucncc of varying boundary layer mixing depths. Even without interannual 

variations of wildfire emissions, FIXEMIS captures much of 

the observed year-to-year variability of August mean 03 at 

Yellowstone (r = 0.67). IAVFIRE with interannually varying fire emissions only moderately improves the correlations 

(r = 0.75). FIXEMIS also captures the observed 03 increase 

from the early 1990s to around 2002, likely reflecting warmer 

temperatures and deeper mixing depths allowing more baseline 03 to mix down to the surface. Over the entire 1988-

2014 (or 198Q..-20!4) period, IAVFIRE gives -0.1 ppbyr- 1 

greater 03 increases in August than FIXEMIS, consistent 

with an overall increase in boreal wildfire activity (Figs. S2 

and S7b). 

Figure 16 shows year-to-year variability in surface MDA8 

03 enhancements from wildfires during summer, as diagnosed by the differences between IAVFIRE and FIXEMIS. 

The results are shown for individual months since fires are 

highly episodic. During the summers of 1998, 2002, and 

2003, biomass fires burned a large area of Siberia and parts 

of the North American boreal forests, raising carbon monoxide across the Northern Hemisphere as detected from space 

(Yurganov et aL, 2005; van der Werf et aL, 20 10). Longrange transport of Siberian fire plumes resulted in 2-6 ppb 

enhancements in surface MDA8 03 at the US western coast 

and in parts of the Intermountain West in AM3. The model 

calculates enhancements in moothly mean MDA8 03 of up 

to 8 ppb from the intense wildfire events in northern California during July 2008 (Huang et aL, 2013; Pfister et aL, 

2013), over Texas-Mexico during June 2011 (Wang et al., 

2015), and in Wyoming-Utah during August 2012 (Jaffe et 

Atmos. Chern. Pbys., 17,2943-2970, 2017 

al., 20!3). The AM3 estimates are roughly consistent with 

a previous analysis of boundary layer aircraft data with and 

without fire intluences (as diagnosed by CH,CN) during June 

2008 over California (Pfister et al.. 2013). 

While fires during hot and dry summers clearly result in 

enhanced 03 at individua1 sites for some summers, the ability 

of AM3 with constant fire emissions to simulate variability of 

03 for a high (e.g., 1988, 2002, 2006) versus low (e.g., 1997, 

2009) fire year (rig. 15b) indicates that biomass burning is 

not the primary driver of observed 03 interannual variability. Year-to-year variability of JJA mean MDA8 o, observed 

at Yellowstone is strongly correlated (r > 0.6) with observed 

large-scale variations in JJA mean daily maximum temperature across the Intermountain West (Fig. 15c). Correlations 

for other ground stations show a similar large-scale feature. 

Similar to the conclusion from Zhang et al. (2014), our analysis indicates that the correlation between 03 and biomass 

burning reported by Jaffe et al. (2008) and Jaffe (2011) at rural sites reflects common underlying correlations with temperature rather than a causal relationship of fire with 03. 

At remote mountain sites (e.g., Yellowstone), warmer surface temperatures lead to deeper mixed layers that facilitate mixing of free tropospheric 03-rich air down to the surface. At sites near sources of air pollution, hot conditions 

enhance regional 03 production and orographic lifting of urban pollution to mountaintop sites during daytime, as occurs 

at Rocky Mountain National Park located downwind of the 

Denver metropolitan area during summer (Sect. 5.4). Reactive volatile organic compound (VOC) emissions from fires 

may enhance 03 production in NOx-rich urban areas (Baker 

et al., 2016), although evaluating these impacts needs highresolution models and better treatment of sub-grid-scale fire 

plumes. 

5.4 Ozone trends in the Denver metropolitan area 

Efforts to improve air quality have led to a marked decrease 

in high-03 events in the Los Angeles Basin as illustrated by 

the annual 4th highest MDA8 03 at Crestline - a regionally representative monitor operated continuously from 1980 

to the present (Fig. 17a). In striking contrast, the 4th highest MDA8 03 in the Denver metropolitan area shows little 

change over the past decades. despite significant reductions 

in NOx (Fig. I) and CO emissions (-80% from 1990 to 

2010; Cooper et al., 2012). Recent field measurements indicate that increased VOC emissions from oil and natural 

gas operations are an important source of 03 precursors in 

the Denver-Julesberg Basin (Gilman et al., 2013; Halliday et 

al., 2016; McDuffie et al., 2016). However, total VOC emissions in Denver may not be increasing over time due to the 

marked reductions in VOC emissions from vehicles (Bishop 

and Stedman, 2008, 2015). We seek insights into the causes 

of the lack of significant 03 responses to emission controls in 

Denver by separately analyzing trends in spring and summer 

(Fig. 17b-c). 

www.atmos-cbem-phys.net/17/2943/2017/ 
56 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2961 

IAVFIRE- FIXEMIS: surface MOAB 03 anomaly 

-·---- ~,.,.. . 

~~~ ----· 

2 [ppb] 

Figure 16. Surface MDAS 03 enhancements from wildfire emissions for individual months in the years with large biomass burning in boreal 

regions (1998, 2002, 2003) and over the WUS (2008. 2011, 2012), as diagnosed by the differences between IAVARE and FIXEMIS. The 

black circle denotes the location of Yellowstone National Park. 

The - 200 x 200 km2 AM3 model is not expected to resolve the urban-to-rural differences between Rocky Mountain National Park and the Denver metropolitan area. How~ 

ever, if observed 03 variability in Denver correlates with that 

at remote sites in the Intermountain West, then model attribution for the remote sites can be used to infer sources of 

observed 03 in Denver. This is demonstrated in Fig. 17b 

for spring using data at three representative sites in Denver, Rocky Flats North, National Renewable Energy Lab 

(NREL), and Welby, with continuous measurements since 

the early 1990s. Year-to-year variability of median MDA8 

03 at these sites during spring correlates strongly with that 

in Great Basin National Park (r = 0. 7). a fairly remote site 

in Nevada not influenced by urban emissions from Denver. 

Median spring 03 observations in Denver increased significantly by -0.3 ppb yc 1, similar to the rate of increase in 

Great Basin National Park, which the model attributes to rising background (Fig. 13a), implying that the tripling of Asian 

emissions since 1990 also raised mean springtime 03 in the 

Denver metropolitan area. Trends in the 95th percentile are 

statistically insignificant. 

During summer, changes in regional emissions and temperature have the greatest impacts on the highest observed 

03 concentrations in polluted environments. Figure 17c 

shows times series of July-August 95th percentile MDAS 

03 in Denver, together with the distribution of daily maximum temperature. In every year since 1993, the highest summer MDA8 03 observed at these sites exceeds the 

70 ppb NAAQS level. There is a small negative trend that is 

swamped by large interannual variability. The summers with 

the highest observed 03 coincide with those with the highest 

observed temperatures, such as 1998,2003.2007,2011 and 

2012. During these summers, enhancements of MDA8 03 

were also recorded In Rocky Mountain National Park, reflectwww.atmos-chem-phys.net/17 n943/20l7/ 

ing enhanced lifting of pollution from Denver under warmer 

conditions (Brodin et al., 2010). Applying quantile regression (e.g., Porter et al., 2015) to daily observations at Rocky 

Flats North over 1993-2015, we find a2ppb'c- 1 sensitivity 

of 95th percentile July-August 03 to changes in maximum 

daily temperature. We suggest that the substantial increases 

in extreme heat occurrence over central North America over 

the last 2 decades, as found by Horton et al. (2015), contribute to raising summer 03 in Denver, which offsets 03 

reductions that otherwise would have occurred due to emission controls in Denver. Potential shifts in the 03 photochemistry regime can also contribute to trends of summer 03 in 

Denver, although advancing this knowledge would require a 

high-resolution air quality model. 

6 Impacts of heat waves and droughts on eastern US 

summer OJ 

We discuss in this section interannual variability and longtenn changes in summer 03 over the EUS, where air stagnation and high temperatures typically yield the highest o, observed in surface air (e.g., Jacob and Winner, 2009). Eval~ 

uating the ability of models to simulate the high-03 anomalies during historical heat waves and droughts is crucial to 

establishing confidence in the model projection of pollution 

extremes under a warming climate. Figure l8a shows comparisons of July mean MDA8 03 at one regionally representative site, the Pennsylvania State University (PSU) CASTNet site, from observations and model simulations. With 

time-varying emissions, the BASE model simulates an 03 

decrease ( -0.45 ± 0.32 ppb yC 1) consistent with observations ( -0.67 ± 0.33 ppbyr- 1) and captures the observed July 

mean 03 interannual variability (r = 0.82) that is correlated 

with large-scale variations in daily maximum temperature 

Atmos. Chern. Phys., 17, 2943-2970, 2017 
57 

2962 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

Los Angeles -3.7'H0.35 ppb yr' Denver ·0.30±0.20ppbyr' 

~980 1985 1990 1995 2000 2005 2010 

(b) 70 rc.-......,=oo.,oc,1""'"P""o"".29t0""•""'-::ppb:::-:,.-::;,------, 

ffi OOenv~Rflats 0.29t0.17ppbyr·lr{GRB)m0.1ll 

"ijE 65 X Denver NREL 0.29±0.2l5 ppb yrl, r {GRB) :Q.B9 

o Oenver'Nelby 0.29±0.18 ppb yr'. r (GRB) =0.70 

~ so 

t 55 

6 50 

~ 45 

~980 

(c)11o 

~ 100 

"' i 90 

0 80 

~ 70 ::; 

1965 

~980 1985 1990 

Year 

~ 

~ 

Figure 17. Surface 03 trends in Denver. (a) Comparison of observed trends in annual fourth highest MDA8 03 at Crestline Los 

Angeles (brown) and in Denver (blue, computed from all monitors 

available in Denver non-attainment counties). (b) Time series of 

observed median MAM MDA8 03 at Great Basin National Park 

(red), in comparison with three monitors in Denver. (c) Time series of observed 95th percentile July-August MDA8 03 in Denver, 

together with statistics (25th, 50th, 75th, 95th) of observed JulyAugust daily maximum temperature at Rocky Flats (red, right axis). 

(r = 0.57). In particular, 03 pollution extremes are successfully simulated during the EUS summer heat waves of 1988, 

1995. 1999,2002,2011 and 2012 (Leibenspergeret al., 2008: 

Fiore et al., 2015: Jia et al., 2016). Year-to-year variations 

in meteorology can explain 30% of the total observed 03 

variability (r = 0.55), as inferred by FIXEMIS with constant 

anthropogenic emissions. If US anthropogenic emissions re« 

mained at 1990s levels (as in FIXEMIS). then anomalies in 

July mean MDAS 03 would have been IOppb greater during 

the 2011 and 2012 heat waves. Loughner et al. (2014) found 

that half of the days in July 2011 would have been classified 

Atmos. Chern. Phys., 17,2943-2970, 2017 

(a) Pennsylvania State Univ [78' W,41' N, 378 ml 

OBS .{).67:!:0.33ppbyr·1,p--G.OO, r{Oy )=0.57 

BASE ·045:.:032 ppbyr '. P-0.01.r(OBS.AM3)"'-0S2 

30 F!XEM!S 0.04;:0.29 ppb yr 1, p=Q.78, r (0BS,AM3)=0.5S 

Figure 18. (a) Time series of July mean MDA8 03 anomalies (relative to 1988-2014) at the Pennsylvania State University (PSU) 

CASTNET site as observed (black) and simulated by the GFDLAM3 model with time-varying (purple) and constant anthropogenic 

emissions (red), along with observed anomalies in July mean daily 

max temperature (gray lines.; right axis). The green triangle denotes 

the 1988 03 anomaly from a sensitivity simulation using BASE 

emissions but with 35% decreases in Vd.o3 (IAVDEP). (b) Time 

series of daily MDA8 03 at PSU from 1 June to 16 July in 1988 

from observations (black), BASE (purple), and IAVDEP simulations {green). 

as 03 exceedance days for much of the mid-Atlantic region 

if emissions had not declined. 

Figure l9a compares the probability density functions of 

MDA8 OJ at 40 EUS surface sites for JJA in the pre-NO, SIP 

Call (1988-2002) versus post-NOx SIP Call (2003-2014) 

periods and during the extreme heat waves of 1988 versus 

2012. Following the NO, SIP Call, the probability distribution of observed JJA MDAS 03 over the EUS shifted downward (solid black versus dotted gray lines in Fig. l9a). The 

median value declined by 9 ppb and the largest decreases occurred in the upper tails, leading to weaker day·to-day OJ 

variability and a narrower 03 range (standard deviation a decreased from 16.4 to l2.9ppb). These observed OJ changes 

driven by regional NOx reductions are even more prominent 

when comparing the heat waves of 1988 versus 2012 (solid 

www.atmos-chem-pbys.net/17/2943/20 17/ 
58 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2963 

0.01 

o.oQ\--~"'---,;,--t.,..----o'rf--'-'i'lffl"-i;;:;;>-rl4o 

(b) Observed MDA8 0 3 (ppb) 

o.os 1988-20021" = 78.9, 0 = 14.5), 19881~ = 86.1, 0 = 16.5) 

~ o.o4 too3-20H \ n 1. -~ l2.0 igi~ ~~: ~i:~; ~ ~ H:M 

.g 0.03 

~ 

.D 0.02 1l 

£ 0.01 

Simulated MDA8 0 3 (ppb) 

Figure 19. (a) Comparisons of probability distributions of summertime MDA8 03 from 40 EUS CASTNet sites for the pre-NOx SIP 

Call (1988-2002: solid black) versus post-NOx SIP Call (2003-

2014; dashed gray) periods and during the extreme heat waves of 

1988 (solid purple) versus 2012 (dashed brown). The median (Jl) 

and standard deviation (a) are shown (ppb). {b) Same as (a), but 

from AM3 BASE. Also shown is the 03 distribution in 1988 from 

a sensitivity simulation with 35% decreases in Vd,O:.; in drought areas (green). (c) Standardized soil moisture departures for JJA 1988 

(calculated by dividing anomalies by the 1979-2010 climatological 

standard deviation, using data from the NOAA Climate Prediction 

Center). 

purple versus dotted brown lines in Fig. 19a): a = 22.3 versus 13.4ppb and median value I' =68.6 versus 52.2 ppb. 

Figure l9b shows the corresponding comparisons using 

the results from AM3 BASE. Despite the high mean model 

bias (-20ppb), AM3 captures the overall structure of the 

changes in the surface 03 distributions and thus the response 

of surface 03 to the NOx SIP Call, including the reductions 

ofhigh-03 events during the heat wave of2012 compared to 

1988. Nevertheless, there is a noticeable difference between 

the observations and simulations in the shape of MDAS 03 

probability distributions for summer !988, particularly in the 

www.atmos-chem-pbys.net/17/2943/2017/ 

upper tail of the distribution above 110 ppb (purple lines in 

Fig. 19a versus b). The BASE model also underestimates the 

observed July mean o, anomaly atPSU in 1988 by -IOppb 

(purple versus black dots in Fig. !Sa). One possible explanation for these biases is that drought stress can effectively 

reduce the 0 3 deposJtion sink to vegetation, leading to an increase in surface 0 3 concentrations as found during the 2003 

European heat wave (Solberg et al., 2008). whereas AM3 

does not include interannuaBy varying dry deposition velocities. 

The North American drought of 1988 ranks among the 

worst episodes of drought in !he US (e.g., Seager and Hoerling, 2014), with JJA soil moisture deficits occurring over the 

northern Great Plains-Midwest region with magnitudes of 1-

2.5 mm standardized departures from the 1979-2010 climatology (Fig. 19c). Huang et al. (2016) found that monthly 

mean 03 dry deposition velocities (Vd.o3 ) for forests decreased by 33% over Texas during the dry summer of 2011. 

Based on this estimate, we conduct a sensitivity simulation for 1988 using BASE emissions but decreasing monthly 

mean V d.o3 from May to August by 35% in the areas over 

North America (20-60° N) where soil moisture deficits in 

1988 exceed -LOa mm (Fig. 19c). This experiment (hereafter referred to as IAVDEP) simulates -10ppb higher July 

mean MDAS 03 at the PSU CASTNet site than the BASE 

model and matches the observed 03 anomaly in 1988 relative to the record mean (green symbol in Fig. 18a). The impacl is largest (up to 15 ppb) on days when observed MDAS 

03 exceeds IOOppb (Fig. 18b; Tm,. 2: 30°C). Simulated JJA 

MDA8 03 at EUS sites in IAVDEP shows an upward shift 

in the probability distribution, particularly in the upper tail 

above II 0 ppb (green versus purple lines in Fig. 19b ), bringing it closer to observations in 1988 (Fig. 19a). The o, standard deviation in IAVDEP (a 18 ppb) shifts towards that 

in observations (<T =22ppb) relative to the BASE model 

(IJ = !6ppb). 

Quantile mapping can be applied to correct systematic distributional biases in surface 03 compared to observations 

(Rieder et al., 2015), but this approach has limitations if 

there are structural biases in the 03 distribution due to missing physical processes in the model (e.g., variations of V d,o3 

with droughts). Travis eta!. (2016) suggest that the National 

Emission Inventory (NEI) for NOx from the US EPA is too 

high nationally by 50%. Decreasing US NOx emissions by 

this amount corrects their model bias for boundary layer 0 3 

by 12 ppb in the southeast for summer 2013, while surface 

MDA8 03 in their model is still biased high by 6 ± 14ppb, 

which the authors attribute to excessive boundary layer mixing. US NOx emissions in the emission inventory used in 

AM3 (Sect. 2.2) are approximately 15% lower !han those 

from the NEI. The 35% decrease in NOx emissions from the 

pre-NOx SIP Call to the post-NOx SIP Call in the model reduces mean 03 by 8 ppb in the EUS, implying that the NOx 

emission bias could correct 40% of our model mean bias of 

- 20 ppb. These estimates support the idea that the common 

Atmos. Chern. Phys., 17,2943-2970,2017 
59 

2964 M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 

2003-2012 minus 1981-1990 

10 aBASE aFIXEMIS 

.IAVASIA .IA~CH• aJAVFIRE 

I 

E 

~ 

] 

v -2 c 

~ -4 

~ -6 

u -8 WUS: -30%NO, 

-10 EA+SA: +100%NOx 

wus 

spring 

wus SEUS 

spr1ng spring 

Figure 20. Summary of US surface 03 trends and drivers. Changes 

in decadal mean MDA8 03 from 1981-1990 to 2003-2012 simulated in a suite of GFDL-AM3 experiments for spring and summer for the western (32--46° Nand 123-102° W), northeastern (37-

450 Nand 90--65° W) and southeastern (30-36° Nand 95-77° W) 

US domains. Observations are not shown because limited data are 

available during 1981-1990. Experiments are color-coded, with the 

error bars indicating the range of the mean change at the 95 % confidence level. Filled circles represent the changes under Background 

(green) and lAY ASIA (purple) when filtered for Asian influence 

(EACOt:::; 67th), while other results are from the unfiltered models. 

The text near the bottom of the plot provides the change in NOx 

emissions over the same period for each region. 

model biases in simulating surface 03 over the southeastern 

US (e.g., Fiore et al., 2009) may partly reflect excessive NOx 

emissions. Some of the positive 03 biases could be also due 

to the averaging over a deep vertical box in the model surface layer('"" 60m in AM3) that can not resolve near-surface 

gradients (Travis et al., 2016). 

7 Conclusions and recommendations 

Through an observational and modeling analysis of interannual variability and long-term trends in sources of 03 over 

the past 35 years, we have identified the key drivers of 03 

pollution over the US. We initially evaluated the trends of 

03 in Asia resulting from rising Asian precursor emissions 

(Figs. 4---6). Our synthesis of available observations and simulations indicates that surface 03 over East Asia has increased by l-2 ppb yr- 1 since 1990 (i.e., 25-50 ppb over 

25 years), with significant implications for regional air quality and global tropospheric 03 burden. Shifting next to the 

US, we find 0.2-0.5 ppb yr- 1 increases in median springtime MDAS 03 measured at 50 % of 16 WUS rural sites, 

with 25% of the sites showing increases across the entire 

03 concentration distribution, despite stringent US domestic 

Atmos. Chern. Phys., 17,2943-2970,2017 

emission controls (Fig. 7). While many prior studies show 

that global models have difficulty simulating 03 increases 

observed at rural baseline sites (e.g., Parrish et al., 2014; 

Strode et aL, 2015), we reconcile observed and simulated 

0 3 trends in GFDL-AM3 with a novel baseline sampling approach (Figs. 3 and 13). We suggest that the common modelobservation disagreement in baseline 03 trends reflects limitations of coarse-resolution global models in resolving observed baseline conditions. This representativeness problem 

can be addressed by filtering model o, for hemisphericscale baseline conditions using the easy-to-implement, lowcost regional CO-like tracers. This approach allows trends 

of 03 measured at baseline sites to be compared directly 

with multi-decadal global model hindcasts, such as those being conducted for the Chemistry-Climate Model Initiative 

(CClv!I; Morgenstern et al., 2017). 

The ability of the GFDL-AM3 model to reproduce observed US surface 03 trends lends confidence in its application to attribute these observed trends to specific processes 

(Figs. 7 to 11). We summarize the overall statistics in Fig. 20, 

drawing upon the decadal mean 03 changes from 1981-

!990 to 2003-2012 in the BASE and sensitivity simulations. The changes in BASE are over the WUS 4.3 ± 1.8 ppb 

for spring and 1.6 ± 1.2 ppb for summer; over the northeast, -1.8 ± 1.7 ppb for spring and -6.0±2.0ppb for summer; and over the southeast, -3.9 ± 1.4 ppb for spring and 

-7.5 ± 1.6ppb for summer. Increasing o, in the WUS under BASE coincides with an increase in background 03 by 

6.3 ± 1.9 ppb for spring and 4.2 ± 2.0 ppb for summer. Under conditions of strong transport from Asia (East Asian 

COt 2: 67th), the background trend rose to 7.6 ± 2.2 ppb for 

spring and 6.0 ± 2.1 ppb for summer (green dots in Fig. 20). 

The WUS background 03 increase reflects contributions 

from increases in Asian anthropogenic emissions (accounting for 50% of background increase in spring; 52% in summer), rising global methane (13% in spring; 23% in summer), and variability in biomass burning (6% in spring; 12% 

in summer; excluding the meteorological influence). 

We conclude that the increase in Asian anthropogenic 

emissions is the major driver of rising background 03 over 

the WUS for both spring and summer in the past decades, 

with a lesser contribution from methane increases over this 

period. The tripling of Asian NOx emissions since 1990 contributes up to 65% of modeled springtime background 03 

increases (0.3-0.5 ppb yr- 1) over the WUS, outpacing o, decreases resulting from 50% US NOx emission controls 

(SO.! ppbyr- 1; Table 2 and Fig. 10). Springtime 03 observed in the Denver metropolitan area has increased at a 

rate similar to remote rural sites (Fig. 17b). Mean springtime 03 above the WUS is projected to increase by - 10 ppb 

from 2010 to 2030 under the RCP8.5 global change scenario 

but to remain constant throughout 2010 to 2050 under the 

RCP4.5 scenario (Fig. 14). As NOx emissions in China continue to decline in response to efforts to improve air quality 

(Krotkov et al., 2016; Liu et al., 2016), rising global methane 

www.atmos-chem-phys.net/17 /2943/2017 I 
60 

M. Lin et al.: US surface ozone trends and extremes from 1980 to 2014 2965 

and NOx emissions in the tropical countries (e.g., India) in 

Asia, where 03 production is more efficient, may become 

more important in the coming decades. A global perspective 

is necessary when designing a strategy to meet US 03 air 

quality objectives. 

During summer, a tripling of Asian anthropogenic emissions from 1988 to 2014 approximately offsets the benefits of 

50% reductions in US domestic emissions, leading to weak 

or insignificant 03 trends observed at most WUS rural sites 

(Figs. 8 and 11 ). Rising Asian emissions contribute to observed summertime 03 increases (0.3 ppb yr- 1) at Yellowstone National Park. Our findings confirm the earliest projection of Jacob et al. ( 1999) with a tripling of Asian emissions. 

While wildfire emissions can result in 2-8 ppb enhancements 

to monthly mean 03 at individual sites in some summers, 

they are not the primary driver of observed 03 interannual 

variability over the Intermountain West (Figs. 15 and 16). Instead. boundary layer depth, high temperatures and the associated buildup of 03 produced from regional anthropogenic 

emissions contribute most to the observed interannual variability of 03 in summer. Summertime 03 measured in Denver during pollution episodes frequently exceeds the 70 ppb 

NAAQS level, with little overall trend despite stringent precursor emission controls (Fig. 17c), likely due to the effects 

of more frequent occurrences of hot extremes in the last 

decade. 

In the eastern US, if emissions had not declined, the 95th 

percentile summertime 03 would have increased by 0.2-

0.4ppbyr-1 over 1988-2014 (Fig. 11c). due to more frequent hot summer extremes and increases in biogenic isoprene emissions ( I-2% yr- 1) over this period (Fig. 12). Regional NOx reductions alleviated the 03 buildup during the 

recent heat waves of 2011 and 2012 relative to earlier heat 

waves (e.g., 1988, 1995, 1999). GFDL-AM3 captures yearto-year variability in monthly mean 03 enhancements associated with large-scale variations in temperatures (Figs. 18 and 

l9). However, there is a need to improve the model repre~ 

sentation of 03 deposition sink to vegetation, in particular its 

reduced efficiency under drought stress, as we demonstrated 

for the severe North American drought of 1988. Such landbiosphere couplings are poorly represented in current models 

and further work is needed to examine their impacts on 03 

pollution extremes in a warming climate. 

Following the NOx SIP Call, surface 03 in the eastern 

US declined throughout its probability distribution, with the 

largest decreases occurring in the highest percentiles during 

summer ( -0.8 to -1.8 ppb yc 1; Fig. 8). Spatially, historical 

03 decreases during non-summer seasons were more pronounced in the southeast, where the seasonal onset of biogenic isoprene emissions and NO.t -sensitive 03 production 

occurs earlier than in the northeast (Figs. 7, 9 and S4). The 

95th percentile 03 concentration in the southeast has even 

decreased during winter. Despite high mean-state biases, 

GFDL-AM3 captures the salient features of observed 03 

trends over the eastern US, including wintertime increases in 

www,atmos-chem-phys.net/17/2943/2017/ 

the 5th and 50th percentiles in the northeast, greater springtime decreases in the southeast than the northeast, and summertime decreases throughout the 03 concentration distribution. These results suggest that NO.x emission controls will 

continue to provide long-term 03 air quality benefits in the 

southeastern US during all seasons. 

8 Data availability 

AU data derived from observations and model simulations 

used in this study are archived at NOAA GFDL and are available to the public upon request to Meiyun Lin. 

The Supplement related to this article is available online 

at doi:10.5194/acp-17-2943-2017-supplement. 

Competing interests. The authors declare that they have no conflict 

of interest. 

Acknmvledgements. This work was supported by funding from 

NASA grants NNHI3ZDAOOIN-AURAST and NNXI4AR47G to 

Meiyun Lin. We thank 0. Cooper, S. Fan and 1. Schnell for helpful 

comments on the manuscript. We acknowledge the free use of 

ozonesonde data at Hong Kong available on www.woudc.org and 

GOME-SCIAMACHY tropospheric NOz column data available on 

www.temis.ni. Arlene M. Fiore acknowledges support under EPA 

Assistance Agreement no. 83587801. The views expressed in this 

document are solely those of the authors and do not necessarily 

reflect those of the agency. Meiyun Lin devotes this article to her father Tianci Lin, who is the motivation of her life and research career. 

Edited by: B. N. Duncan 

Reviewed by: two anonymous referees 

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66 

Attachment 

c 
67 

Memorandum 

Date: June 13, 2018 

To: Timothy S. Franquist, Director, Air Quality Division 

From: Yi Li, Environmental Engineering Specialist III 

Subject: Investigation of intrastate, interstate and international contributions to high 

concentrations of ozone in Yuma, Arizona 

Executive Summary 

Air quality monitoring in Yuma, Arizona has shown the area is violating the 2015 National 

Ambient Air Quality Standard (NAAQS) for ozone. However, in comparison to many other 

ozone nonattainment areas (such as the Phoenix-Mesa Nonattainment Area), the Yuma area 

emits much less ozone precursors (nitrogen oxides and volatile organic compounds). This 

indicates that high concentrations of ozone in the Yuma area are the result of transport into the 

area and not due to local emissions. This memorandum summarizes two analyses of ozone 

concentrations in the Yuma Area: (1) a comparison of ground-based meteorological and ozone 

monitors in Yuma, Arizona, United States, and San Luis Rio Colorado, Sonora, Mexico; and (2) 

an analysis of data from the NASA Ozone Monitoring Instrument on the Aura satellite. 

Ground-Based Monitor Data 

The ground based monitors straddle the international border and are 18 miles (29 km) apart. 

Data collected by the monitors shows that the ambient ozone concentration is highly correlated 

at both sites (r2

=0.72), and that higher ozone concentrations at the Yuma site are associated 

with wind coming from the south and southwest. 

NASA Ozone Monitoring Instrument Data 

Given the location of Yuma at the nexus of Arizona, California, and Mexico, we thought it most 

appropriate to look at relative change concentrations in Arizona, northwestern Mexico and 

southern California from 2005 to 2017. Due to interference from the ozone layer of the 

stratosphere, we are not able to obtain direct ozone concentration data. Therefore, the ozone 

precursor Nitrogen Dioxide (NOz) was investigated. Our analysis found: (1) NOz concentrations 

are highest in southern California and steadily decreasing, (2) NOz concentrations are lower in 

Arizona and also decreasing, and (3) N02 concentrations in northeastern Mexico are low but 

increasing. We also found that the area directly around the monitor was decreasing in 

concentrations for the 2005 to 2017 period, with most of the decrease from Arizona and 

California. 
68 

Page 2 of9 

June 13,2018 

Background 

Yuma, Arizona is the county seat of Yuma County, which shares a border with California and the 

Mexican states of Sonora and Baja California. The 2017 Yuma design value for ambient ozone 

concentrations (the design value covers the years 2015-17) was near the levels measured in the 

Phoenix-Mesa nonattainment area for the same period (Figure 1). The design value was 72 ppb 

in Yuma and 76 ppb in Phoenix-Mesa. 

Design Values for 2017 Ozone (ppb) 

Yuma, AZ Phoenix~ M-esa, AZ 

Elevated ozone concentrations are understood to be generated by high emissions of ozone 

precursors (mainly NO, and volatile organic compounds), which is in turn associated with 

human activity. However, when looking at levels of emissions and human activity, the Yuma 

area is much less than the Phoenix-Mesa area (Figure 2). 

2014 Emissions {tons) 100,000 ·-------,;;:;;;;--, 

2015 Population 2014 Total VMT 

90,000 

80,000 

70,000 

60,000 

50,000 

40,000 

30.000 

20,000 

10,000 

Yuma, A2 Phoenix, Mesa, 

AZ 

5,000.000 

4,500,000 

4.000,000 

3500,000 

3,000,000 

2,500,000 

2,000,000 

1,500,000 

1,000,000 

500.000 

0 

40,000 

33,000 

30,000 

25,000 

20.000 

15.000 

10,000 

5,000 

Yuma,AZ Phoenix·Mesa. Yuma, AZ Phoenix-Mesa, 

AZ 
69 

Page 3 of9 

June 2018 

Ground-Based Monitoring Data 

In addition to the ozone monitor in Yuma, ADEQ placed a monitor in San luis Rio Colorado, 

Sonora Mexico. The monitors are 18 miles apart and on opposite sides of the international 

border. The location of the monitors is in Figure 3. 

Legend * Monftors c:J2015ProposedYumaNAA 

c:J County/Nation Boundary EZ.J Tribal Land 

Figurl.! 3 O::onc Jfrmitoring Location'• 

Data collected by the monitors for the 2017 ozone season is in Figures 4 and 5. In Figure 4, the 

data is shown with the Yuma measurements on top. In Figure 5, the data is shown with both 

stations superimposed. The ozone concentrations at both sites are correlated with an r-squared 

value of 0. 72. 
70 

20!8 
71 

Page 5 of9 

June 2018 

Maximum Daily 8 hrs Average Ozone in Yuma 

NW NE 

W N 

date 

contribution weighted by frequency 

NASA Ozone Monitoring Instrument Data 

Instrumentation 

The Ozone Monitoring Instrument (OM I) is spectrometer on NASA's Aura satellite (launched 

on July 15, 2004). The OMI instrument is a nadir viewing (downward facing) imaging 

spectrograph that measures the solar radiation backscattered by the Earth's atmosphere and 

surface over the entire wavelength range from 270 to 500 nm with a spectral resolution of 

about 0.5 nm. OM! combines the advantages of previous satellites (e.g., GOME, SCHIMACHY, 

OMPS etc), measuring the complete spectrum in the ultraviolet/visible wavelength range with a 

very high spatial resolution (13 km x 24 km) and dally global coverage{~ local time 1:45pm). 

Due to interference from the ozone layer of the stratosphere, we are not able to obtain direct 

ozone concentration. As an ozone precursor, nitrogen oxides (N02) play an important role in 

formation of ground-level ozone through several series of reactions with volatile organic 

compounds (VOCs) catalyzed by sunlight (Figure 7). 
72 

Resolution 

NASA standard NASA SP 2005- 2017 

Laughneret 

aL(2016) 

Krotkov et al.(2017); 
73 

Page 7 of9 

June 13,2018 

OMI N02 vertical column densities from Level 2 products are gridded to 0Sx0.667" grid cells 

using quality flags and filtering criteria following the methods used in Jiang et al. (2018) and Qu 

et al. (2017). We processed the N02 retrieval data obtained from those three products for 

Yuma and its downwind areas including southern California, Arizona and Northern Mexico from 

2005 to 2015. The whole region is within the area defined by latitude 25"N to 40"N and 

longitude 100"W to 125"W. The unit of retrieval N02 concentrations is molecules cm-2, which is 

different from the parts per billion (ppb) we normally use. In order to clearly show the changes 

of retrieval N02 concentrations in the last ten years, the percentage difference is calculated 

using the equation below: 

Results 

(2014- 2015 Average) (2005- 2006 Average) x lOO% 

(2005 - 2006 Average) 

b) BEHR Product 

c-•• -=--~--- -·-·--··-~·-···-· ·--~ ·-···· 

Year NASA Standard Product NASA Standard Product 

[%] 

05 0 

Year 

DOMINO Product 

Year 

10 

10 

12 

" 

Figure 8 Percentage changes(%; r~(retricvaf ;\'()] conccntratiun'i (a) and trend ana~~·sfs (b) from three OM! XO:J products 
74 

Page 8 of9 

June 13,2018 

Figure 8a shows a decreasing trend in southern California and Arizona. Especially, we notice a 

significant N02 decrease in metropolitan areas such as los Angeles, San Francisco, and Phoenix; 

however, an increasing trend of N02 is spotted in northern Mexico. 

In order to qualify the trends in each area, we averaged the annual N02 concentration(s) (only 

the area shown in the Figure 8a) and grouped them as California, Arizona and Mexico, 

respectively. Trend analysis was conducted for each area using Theil regression (Theil, 1992) 

and the Mann-Kendall test (Gilbert, 1987; Marchetto eta!., 2013). We defined an increasing 

(decreasing) trend as a positive (negative) slope of the Theil regression, while the statistical 

significance of a trend was determined by the Mann-Kendall test (p value). A goth percentile 

significance level (p <0.10) was assumed as in a previous study (Hand eta!., 2012). The results 

of trend analysis are presented in the Figure 8b. The trends from the three products show the 

same patterns, that N02 is decreasing in Southern California and Arizona, while increasing in 

Mexico (except NASA SP, which showed no significant trend for Mexico). The results from 

another NOz study recently conducted by Majid et al. (2017) also showed a similar trend for 

California and Arizona (Figure 8). 

Future Work 

Volatile Organic Compounds (VOCs), as another important ozone precursor, should also be 

investigated. Unfortunately, OMI only has one product available for formaldehyde (HCHO) for 

the period from 2005 to 201S. This data is currently being reviewed with a summary available in 

the near future. 

References 

Lamsal, LN., Duncan, B.N., Yoshida, Y., Krotkov, N.A., Pickering, K.E., Streets, D.G. and Lu, Z., 2015. US 

N02 trends (2005-2013): EPA Air Quality System (AQS) data versus improved observations from the 

Ozone Monitoring Instrument (OM I). Atmospheric Environment, 110, pp.B0-143. 

Uu, F., Zhang, Q., Zheng, B., Tong, D., Van, l., Zheng, Y. and He, K., 2016. Recent reduction in NO x 

emissions over China: synthesis of satellite observations and emission inventories. Environmental 

Research Letters, 11(11), p.114002. 

Duncan, B.N., Lamsal, LN., Thompson, A.M., Yoshida, Y., Lu, Z., Streets, D.G., Hurwitz, M.M. and 

Pickering, K.E., 2016. A space-based, high-resolution view of notable changes in urban NOx pollution 

around the world (2005-2014). Journal of Geophysical Research: Atmospheres, 121(2), pp.976-996. 

Majid, A., Martin, M.V., Lamsal, LN. and Duncan, B.N., 2017. A decade of changes in nitrogen oxides 

over regions of oil and natural gas activity in the United States. Elem Sci Anth, 5. 

Russell, A.R., Perring, A. E., Valin, LC., Bucsela, E.J., Browne, E.C., Wooldridge, P.J. and Cohen, R.C., 2011. 

A high spatial resolution retrieval of NO 2 column densities from OM I: method and evaluation. 

Atmospheric Chemistry and Physics, 11(16), pp.8543-8554. 
75 

Page 9 of9 

June 13,2018 

Krotkov, N.A., Lamsal, LN., Celarier, E.A., Swartz, W.H., Marchenko, S.V., Bucsela, E.J., Chan, K.L, Wenig, 

M. and Zara, M., 2017. The version 3 OMI NO 2 standard product. Atmospheric Measurement 

Techniques, 10(9), p.3133. 

Bucsela, E.J., Krotkov, N.A., Celarier, E.A., lamsal, LN., Swartz, W.H., Bhartia, P.K., Boersma, K.F., 

Veefkind, J.P., Gleason, J.F. and Pickering, K.E., 2013. A new stratospheric and tropospheric N02 

retrieval algorithm for nadir-viewing satellite instruments: applications to OM I. Atmospheric 

Measurement Techniques, 6(10), p.2607. 

Boersma, K.F., Eskes, H.J., Veefkind, J.P., Brinksma, E.J., VanDer A, R.J., Sneep, M., Van Den Oord, G.H.J., 

levelt, P.F., Stammes, P., Gleason, J.F. and Bucsela, E.J., 2007. Near-real time retrieval of tropospheric 

NO 2 from OM I. Atmospheric Chemistry and Physics, 7(8), pp.2103-2118. 

Jiang, Z., McDonald, B.C., Worden, H., Worden, J.R., Miyazaki, K., Qu, Z., Henze, D.K., Jones, D.B., 

Arellano, A. F., Fischer, E.V. and Zhu, L., 2018. Unexpected slowdown of US pollutant emission reduction 

in the past decade. Proceedings of the National Academy of Sciences, p.201801191. 

Qu, Z., Henze, D.K., Capps, S.L., Wang, Y., Xu, X., Wang, J. and Keller, M., 2017. Monthly top-down NOx 

emissions for China (2005-2012): A hybrid inversion method and trend analysis. Journal of Geophysical 

Research: Atmospheres, 122(8), pp.4600-4625. 

Theil, H., 1950. A rank-invariant method of linear and polynomial regression analysis, 3; confidence 

regions for the parameters of polynomial regression equations. lndagationes Mathematicae, 1(2), 

pp.467-482. 

Gilbert, R.O., 1987. Statistical methods for environmental pollution monitoring. John Wiley & Sons. 

Marchetto, A., Rogora, M. and Arisci, S., 2013. Trend analysis of atmospheric deposition data: a 

comparison of statistical approaches. Atmospheric environment, 64, pp.95-102. 

Hand, J.L, Schichtel, B.A., Maim, W.C. and Pitchford, M.L, 2012. Particulate sulfate ion concentration 

and SO 2 emission trends in the United States from the early 1990s through 2010. Atmospheric 

Chemistry and Physics, 12(21), pp.10353-10365. 
76 

Attachment 

D 
77 

6/11/2018 

@ Ui~j\'ORLD BANK 

(http://www.worldbank.org/) 

Underst<mdmg Poverty Uen/urderstandmg-poverty] Health (/enltopiclhe.alth) 

Poverty and Health August25,Z014 

Poverty and Health 

B (mailto:?body~http%3A%2F%2Fwww.worldbank.org%2Fen%2Ftopic%2Fhealth%2Fbrlef%2Fpoverty·health%3Fc!d%3DEXT _WBEmatiShar~XT&£bjectinove~20< 

Context 

Poverty is a major cause of ill health and a barrier to accessing health care when needed. This relationship is financial; the poor cannot afford to purchase 

those things that are needed for good health, including sufficient quantities of quality food and health care. But, the relationship is also related to other 

factors related to poverty, such as lack of information on appropriate health-promoting practices or lack ofvotce needed to make social services work for 

them. 

Ill health, In turn, is a major cause of poverty. This ts partly due to the costs of seeking health care, which include not only out-of-pocket spending on care 

{such as consultations, tests and medicine), but also transportation costs and any informal payments to providers. It is also due to the considerable loss of 

income associated with Illness In developing countries, both of the breadwinner, but also of family members who may be obliged to stop workmg or 

attending school to take care of an 1!1 relanve. ln additiOn, poor families coping w1th 11!ness might be forced to sell assets to cover med1cal expenses, 

borrow at high mterest rates or become mdebted to the community. 

Strong health systems (http://www.wor!dbank.org/enltoptelhealth/x/hea!thsystems) improve the health status of the whole populatiOn, but espeCially of 

the poor among whom ill health and poor access to health care tends to be concentrated, as well as protect households from the potentially catastrophiC 

effects of out-of-pocket health care costs. In general, poor health is disproportionately concentrated among the poor. 

Strategy 

The World Bank's work in the area of health equity and financial protection is defined by the 2007 Health, Nutrition and Population Strategy 

(http:!lgo.worldbank.org/QY4FTNVJR1). The strategy identifies "preventing poverty due to illness (by improving financial protection)" as one of its four 

strategiC objectives and commits the Bank's health team, both through its analytical work and its regional operations, to addressing vulnerability that 

anses from health shocks. 

The strategy also stresses the importance of equity in health outcomes in a second strategic objective to "improve the level and distnbut!on of key health, 

nutnt1on and population outcomes ... particularly for the poor and the v~!nerable". 

The Bank supports governments to implement a variety of policies and programs to reduce inequalities in health outcomes and enhance financial 

protection. Generally, thiS involves mechamsms that help overcome geographic, social and psycho!ogKal barriers to accessing care and reducing out-ofpocket cost of treatment Examples include: 

http:IIWNW.worldbank.org/enltopiclheaHh/brief/poverty-health 113 
78 

6/11/2018 Poverty and Health 

1. Reducing the direct cost of care at the point of serv1ce. e.g. through reducing/abol1shmg user fees for the poor or expandmg health insurance to the 

poor (including coverage, depth and breadth). 

2. Increasing efficiency of care to reduce total consumption of care, e.g. by limiting "irrational drug prescribing," strengthening the referral system, or 

improvmg the quality of providers (especially at the lower level) 

3. Reducing mequalities in determinants of health status or health care utilizatiOn, such as reducing distance (through providing services closer to the 

poor), subs1d1zing travel costs, targeted health promot1on. conditional cash transfers. 

4. Expanding access to care by using the private sector or public-private partnerships. 

The Bank's health team also promotes the monitoring of equity and financial protection by publishing global statistics on inequalities in health status, 

access to care and financial protection, as well as training government officials, pohcymakers and researchers in how to measure and monitor the same. 

Re5ults 

Examples of how World Bank projects have improved health coverage for the poor and reduced financial vulnerability 1ndude: 

The Rajasthan Health Systems Development Project (http://www.worldbank.org/proJects/P050655/rajasthan-health-systems-deve!opment-project? 

!ang=en)resulted in improved access to care for vulnerable lnd1ans. The share of below-poverty line Indians in the overall inpatient and outpatient load at 

secondary facilities more than doubled between 2006 and 2011, well exceeding targets. In the same period, the share of the vulnerable tnbal populations 

m the overall pat1ent compositiOn tripled. 

The Georgia Health Sector Development Project (http://www.worldbank.org/projects/P040555/health-sector-development-project?!ang::en) supported 

the government of Georgia 1n implementing the Medical Insurance Program for the Poor, effectively increasing the share of the government health 

expenditure earmarked for the poor from 4% in 2006 to 38% in 2011. It also increased the number of health care visits of both the general population and 

the poor, but by more for the poor (from 2 per capita per year to 2.6) than for the general population (from 2 to 2.3) over the same time period. 

The Mekong Regional Health Support Project (http://www.worldbank.org/proJeCts/P079663/mekong-regional-health-support-project?lang:ooen) helped 

the government of Vietnam to tnc:rease access to (government) health insurance from 29% to 94% among the poor, as well as from 7% to 68% among the 

near-poor. Hospitalization and consultation rates, at government facilities, also increased among both the poor and near-poor. 

RELATED 

Analyzing Health Equity Using Household Survey Data (http://www.worldbank.org/en/topic/health/publicatiDn/analyzing-hea!th-equity-us!ng-householdsurvey-data) 

AdePT Software 

{http:/ I econ. worldbank.org!WBSITE/EXTERNAUEXTDEC/EXTRESEARCH/EXTPROG RAMS/EXT ADEPT /O,menu PK: 71 08381 -pagePK:64168176-piPK:64168140-

theSitePK: 71 08360, OO.html) 

RELATED 

Health Equity and Financial Protection Datasheets (http://W\'VW.worldbank.org/en/topic/health/pub!ication/health-equity-and-flnanCial-protectiondatasheets) 

Health Equity and Financial Protection Country Reports (2012) (http://www.worldbank.org/en/topl'c/hea!th/publication/health-equity-flnancla!·protectioncountry-reports) 

ADePT T r alning Resource Center (len/topic/health/brief/ adept -resource-center) 

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Attachment 

E 
81 

MEDICINE AND PUBLIC ISSUES 

Poverty and Ill Health: Physicians Can, and Should, 

Make a DUference 

Michael McCally, MD. PhD; Andrew Haines. MD; Oliver Fein. MD: Whitney Addington, MD: 

RobertS. Lawrence, MD; and Christine K. Cassel, MD 

A growing body of research confirms the existence of a 

powerful connection between socioeconomic status and 

health. Thi-s research has implications for both clinical practic-e and public po1icy and deserves to be more widery 

understood by ph)"icians. Absolute poverty. which implies 

a lack of resources deemed ne<essary for survival, is self· 

evidently assotiated with poor health, particularly in less 

developed countries. OVer the pa"St two decades. economic 

decline or stagnation has reduced the incomes of 1.6 bil~ 

lion people. Strong evidence now indicates that retative 

poverty. which is defined in relation to the average re~ 

sot.~rces available in a society. is also a major determinant 

of health in industrialized countries. For example, pen:ons 

in U.S. statet with income distributions- that are more 

equitable have longer life expectancies than persons in less 

egalitarian states. 

!here are numerous possibte approa<:hes to improving 

the health of poor populations. The most essential task is 

to ensure the satis-faction of basic human needs: shelter. 

dean air, safe drinking water. and adequate nutrition. 

Other approaches include reduting barriers to the adoption of healthier modes of living and improving access to 

appropriate and effective health and social services. Physi~ 

dans as clinicians. educators. research scientists. and advoutes for policy change can contribute to all of these 

approaches. Physicians and other health professionals 

should understand poverty and its effects on health and 

should endeavor to influence policymakers nationally and 

internationally to reduce the burden of ill health that is a 

conse-quence of poverty. 

Ann !nrmt M~tL 199S:lZ9:726-7:.U_ 

From Mounc Sinai Schoot of Mcdtcine and Com~ll Urti\'trsity 

Medical College. New York, New York; f(Qyal Free and Univer~ 

sity College Schools of Medicine. London. Unitt!d Kifigdom; 

Rush Sthool \)f Medicine. Chicago. Ulinol:'i-: and Johns Hopkin$ School o( Public Hc:allh, &himo~. Marytand. For current au* 

thof addresses. !iCe end of text. 

Poverty and social inequalities may be the most 

important determinants of poor health worldwide. Socioeconomic differences in health status exist even in industrialized countries where access to 

modern heallh care is widespread (I). In this paper, 

we make a formal argument for physician concern 

and action about poverty based on the following 

assertions. Physicians have a professional and a 

moral responsibility to care for the sick and to 

prevent suffering. Poverty is a significant threat to 

the health of both individual persons and populations; thus. physicians have a social responsibility to 

take action against poverty and its consequences for 

health. Physicians can help improve population 

health by a<ldres.<ing poverty in their roles as clinicians, educators, research scientists. and participants 

in policymaking. 

Concepts of Poverty and Health 

Poverty is a multidimensional phenomenon that 

can be defined in both economic and social terms. 

An economic measure of p<.werty identifies an income sufficient to provide a minimum level of consumption of goods and scrvi<:es. A sociologic measure of poverty is concerned not with consumption 

but with social participation (2). Poverty leads to a 

person's exclusion from the mainstream way of life 

and activities in a society (3). There is a difference 

between absolute poverty, which implies a lack of 

resources. deemed necessary for survival in a given 

society. and relative poverty. which is defined in 

relation to the average resources available in a society. Economic measures are eaS}' to obtain, but 

social measures may provide a better understanding 

of the causes and consequences of poverty. Steps 

have been taken toward the development of indices 

of deprivation, which have promising uses in health 

services and public health research ( 4 ). 

In 1978, the World Health Organization (WHO), 

in the Alma-Ata Declaration, spelled out the dependence of human health (defined broadly) on social 

and economic development and noted that adequate living conditions are necessary for health (5). 

Despite their knowledge of this, governments and 

major development organizations have largely con726 10 1998 American College of Physicians-American Society of Internal Medicine 

Downloaded From: http:l/annals.orgf by Tim Franquist on 06/tl/2018 
82 

tinued to view health narrowly as a responsibility of 

the medical sector, outside the scope of economic 

development efforts. Consequently, governments have 

encouraged many large-scale but narrowly focused 

economic development elforts, ignoring the connection between poverty and health (6). In developed 

countries, governments promote various practices. 

such as heavy pesticide applications, that are designed to increase economic development and com· 

petitiveness but that are environmentally unsound 

and personally unhealthy. 

Poverty causes Death and Illness on a 

Massive Scale 

During the second half of the 1980s, the number 

of persons in the world who were living in extreme 

poverty increased. Currently, extreme poverty afflicts more than 20% of the world's population. A 

recent report from WHO points out that up to 43% 

of children in the developing world-230 million 

children- have low height for their age and that 

about 50 million children have low weight for their 

height (7). Micronutrient malnutrition (deficiencies 

of vitamin A. iodine, and iron) affects about 2 billion persons worldwide. 

It has been estimated that if developing countries 

enjoyed the same health and social conditions as the 

most developed nations, the current annual toll of 

more than 12 million deaths in children younger 

than 5 years of age could be reduced to less than 

400 000. An average person in one of the least 

developed countries has a life expectancy of 43 

years: the life expectancy of an average person in 

one of the most developed countries is 78 years (7). 

This is not to deny that real gains in health have 

occurred in recent decades. For example, since 

1950, life expectancy at birth in several developing 

countries has increased from 40 to more than 60 

years. Similarly, worldwide, mortality rates for chi!· 

drcn younger than 5 years of age decreased from 

280 to 106 per 1000, on average. Some countries 

show much sharper declines (7), hut indices of 

health in these countries still fall far short of those 

in wealthier nations. 

Poverty and Sustainable Development 

The relation between poverty and health is complex, and we believe that it is best understood in the 

framework of a new notion of "ecosystem health." 

which places poverty and health in the nexus of 

environment, development, and population growth 

(8). Ecosystems provide the fundamental underpin· 

ning for public health in both developed and less 

developed countries, not only through food produc· 

tion, for example, but also through their roles in 

economic development. For instance, they supply 

forest resources and biomass fuels and serve as 

habitats for the vectors of disease (9). Sustainability 

is produced by using resources in ways that meet 

the needs of current populations without compromising the ability of future generations to meet 

their own needs ( 10) and is predicated on the need 

to ensure a more equitable sharing of !<>day's re· 

sources. Meeting the needs of the world's poor implies limitation of the current use of resources by 

industrialized nations. 

Barriers to the benefits of development include 

rapid population growth, environmental degradation, and the unequal distribution of resources. At 

one extreme, traditional. preindustrial societies an:: 

characterized by relatively high birth rates coupled 

with high death rates attributable to acute infectious 

diseases and the hazards of childbearing: this leads 

to slow population growth. At the other extreme, in 

the most developed countries. population stability 

has occurred. In the intermediate situation, in less 

developed countries, population stability ha.< not 

been reached, and the global population thus continues to increase. In some less developed countries. 

a "demographic trap" eltists in which the development of resources cannot keep pace with the requirements of the growing population and poverty is 

worsened (II). The most developed countries cs· 

cape the trap by buying additional essential resources in the global marketplace to make up the 

dilference. 

Environmental degradation exaggeratl"S the imbalance between population and resources, increases the costs of development, and increases the 

extent and severity of poverty. For example, the 

need for fuel wood, timber for export, and farmland 

results in deforestation, which increases soil erosion, 

Hooding, and mud slides and reduces agricultural 

productivity. As a result, biological diversity is lost, 

production becomes increasingly reliant on pesticides and fertilizers, and use of expensive fossil fuels 

increases. Water is a critical resource. In Punjab, 

the breadbasket of India. the major aquifer is decreasing at a rate of 20 em per year, threatening 

health by reducing agricultural productivity and the 

supply of clean water ( 12). Economic development 

without regard to long-term environmental and social 

consequences also threaten.• sustainability by damaging the systems that sustain healthy communities. 

Inequalities In Health Are Socially 

Determined 

The strong and pervasive relation between an 

individual person's place in the structure of a soci1 November 199M • A11nab of lntm~tJ/ Mediciltt! • Volume 129 • Numbcr9 71.7 

Downloaded From: http://annals.org/ by Tim Franquist on 06/11/2018 
83 

... V. Unskilled 

i ... lt , .. 

l 

liE 120 

1 

... 

j 100 

.. , .. , , .. , . ... 1t11 .... Year 

Flgu.r. 1~ Compilisoo of ttandardiled rnortafrty ratiO!- for men 15 to &4 ~n of otge by sodal dau over fiw dtadti h'l Engltnd .tnd Wales. fi{JUfts h..wt ~n .ldJUS.ted to the dass1f1<::atton of OC:Ce.JIJ<ltlon~ USfd 1n 19S l lnfOfi'TI.attOO oo me-n 10 to 64 years of age m Gleat Bnta1n w.n. obt.l~ from 

Blad; .md c.o!!i!'iJ9U!S {!Sl 

ety and his or her health status has been clearly plasma cholesterol levels) explain only about 25% 

shown in research conducted over the past 30 years to 35% of the differences in mortality rates among 

(13-16). In 1973, Kiragawa and Hauser (17) published persons of different incomes (Figure 2) (23, 24). 

convincing evidence of an increase in the dilferen- An equally striking finding is Wilkinson's obsertial mortality rates ae<:ording to socioeconomic level vations of the relation between income distribution 

in tbe United States between 1930 and 1960. They and mortality (25, 26). Wilkinson assembled two 

found that rates of death from most major causes sets of observations. First, he found no clear relawas higher for persons in lower social classes. In Brit- tion between income or wealth and health when 

ain, research into health inequalities was summa- comparisons were drawn between countries (for exrized in 1980 in The Black Report ( 18), which was ample, there is no relation between per capita gross 

updated in 1992 (19) and is currently under review domestic product and life expectancy at biTth in 

bY an official working group. The report was pre· comparisons between developed countries at similar 

pared by a labor government-appointed research levels of industrialization). But Wilkinson also showed 

working group chaired bY Sir Douglas Black, for- a strong relation between income inequality and 

merly Chief Scientist at the Department of Health mortality within countries, a relation that has been 

and, at the time, President of the Royal College of confirmed more recently (27, 28). The countries 

Physicians. The Black Report concluded that ''there with the longest life expectancy arc not necessarily 

are marked inequalities in health between the social the wealthiest but rather are those with the smallest 

classes in Britain" (Figure I). Marmot and col· spread of incomes and the smallest proportion of 

leagues, in the well-known Whitehall studies of Brit- the population living in relative poverty. These 

ish civil servants begun in 1967, showed that mor- countries (such as Sweden) generally have a longer 

tality rates are three times greater for the lowest life expectancy at a given level of economic de'·el· 

employment grades (porters) than for the highest opment than less equitable nations (such as the 

grades (administrators) and that no improvement United States). 

ae<:urred between 1968 and 1988 (20-22). Recent analysis of U.S. data supports earlier obSuch findings could, in theo.y. be due to differences servations that the distribution of wealth within soin age, smoking. nutrition, types of employment, cictics is associated with all-cause mortality and sugaccident rates, or living conditions, hut the White· gcsts that the relative socioeconomic position of the 

hall study participants were from a relatively homo- individual in U.S. society may be associated with 

geneous population of office-based civil servants in health. Populations in U.S. states with income dis· 

London. They had largely stable. sedentary jobs and tributions that are more equitable have longer life 

access to comprehensive health care. A second ob· expectancies than do those in less egalitarian states, 

servation of the Whitehall investigations. confirmed even when average per capita income is taken into 

bY the Multiple Risk Factor Intervention Trial account (27, 28). Authors of the studies that re-

(MRFIT) studies in the United States. is that con· vcalcd these findings recently introduced the notion 

ventional risk factors (smoking. obesity, low levels of "soeial capital," which is defined as civic engageof physical activity, high blood pressure, and high ment and levels of mutual trust among community 

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84 

members:, as an important variable intervening between income inequality and health status (29). 

Evans and associates (IS) suggest that ones control 

of the work environment is an important connection 

between social and occupational class and mortality. 

The Robin Hood index, also known as the Pictra 

ratio, is used to estimate the percentage of total 

income that would have to be transferred from 

groups above the mean to groups below the mean 

to equalize income distribution. A higher Robin 

Hood index value represents greater disparity in 

incomes. The strong correlation between income 

distribution and mortality rates shows that income 

disparity, in addition to absolute income level, is a 

powerful indicator of overall mortality (FigUre 3) (27). 

Inequalities in Income and Health 

Are Worsening 

Many of the improvements in life cxpectan<')l and 

infant mortality rates that have occurred around the 

world are overshadowed by the countervailing influence of increasing disparities between rich aod poor. 

Since 1980, economic decline or stagnation has af· 

fected I 00 countries, reducing tbe incomes of 1.6 billion persons (19). Between 1990 and 1993,the average 

income decreased by 20% or more in 21 countries, 

particularly countries in eastern Europe and the 

countries of the former Soviet Union (30). The net 

worth of the world's 358 richest persons is equal to 

the combined income of the poorest 45% of the 

world's population: 2.3 billion persons. Between 

1960 and 1991, the ratio of the global income of the 

richest 20% of the world's population relative to the 

poorest 20% increased from 30:1 to 61:1 (30. 31). 

Many recent improvements in population health 

have been chreatcncd and, in some cases, reversed 

at the same time that income differentials have wid· 

ened. For example, the proportion of underweight 

children in Africa may decrea•e from 26% in 1990 

to 25% in 2005, but tbe total number of under· 

weight children is projected to increase from 31.6 

million to 39.2 million because of population growth. 

In the United States and the United Kingdom. 

income distribution has become more unequal. According to the United Nations Development Pro· 

gramme. income distributions within each of these 

countries are now among the most unequal distri-

§ ~ ~ ~ I I § § ~ I ~ 0 • ~ ~ ; ~ ; ~ ~ ; j ~ S = ~ ~ ~ ~ R ~ I ~ 

Income, 1980 U.S. dollllrs 

Figure 2. lnc:ome ilnd age-adjusted mondty nttes among lOO 000 white men In n United S1irtn. o..rt.l obl.W'Il'd frQm Smnl1> ¥'ld col~ (23t 

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85 

butions in the world's industrialized countries (31, 

32). For example, in the United Kingdom. the pro· 

portion of persons with an income less than half of 

the national average increased from less than 10% 

in 1982 to more than 20% in 1993. and unskilled 

men in Scolland now have a mortality rate three 

times that of professional men (33). This represems 

a widening from a twofold dill'erential in the early 

1970s. In the United Kingdom, the difference in 

mortality rates between rich and poor has increased 

because mortality rates have decreased faster 

among the rich than among the poor (34), and the 

proportion of children below the official poverty line 

has tripled in the past 10 years (35, 36). In the 

United States, inequality in in<'Omc increased in all 

states except Alaska between 1980 and I Y9tl (37). 

Effective Interventions Reduce Ill Health 

Due to Poverty 

Some evidence suggests that improving the income of the poorest persons improves health in 

both developed and less developed countries. Inter· 

national data have been used to show that the dou· 

bling of per capita income (adjusted for purchasing 

power parity) from $1000, using 1990 figures, cor· 

responds to an increase of II years in life expect· 

ancy. The relation Oancns of above an average per 

capita income of approximately $5000 (Figure 4) 

(30). The distribution of income within households 

also inRucnces health. It has been suggested, for 

example, that it takes 10 times more spending to 

achieve a given improvement in child nutrition in 

102 

06 

" I llO 

I .. i 

I 78 .. 

* VT 

0 

72 

.. 

0 

611 

"' 'l1 "' "' "' 

Guatemala when income is earned by the father 

than when it is earned by the mother because the 

mother is more likely to spend the money on cs· 

sentials for the family (30). 

An important, possibly unique, randomized trial 

in Gary, Indiana, suggests that increasing the income of poor expectant mothers receiving welfare 

increased the birthweight of their babies (38). Education, particularly for mothers, has dramatically af· 

fectcd health. In Peru, for instance, the children of 

mothers with 7 or more years of education have a 

reduction in child mortality of nearly 75% compared with the children of mothers with no schooling. Studies in several countries have shown that 

mothers who have completed secondary or higher 

education arc much more lil..cly to treat childhood 

diarrhea appropriatcl)· with oral rehydration therapy. Families are also likely 10 be smaller when 

women are more educated (30). 

A recent systematic review of the ell'ectivencss of 

health service interventions, predominantly in indus· 

trialized countries. to reduce poverty-related inc· 

qualities in health suggests several characteristics of 

interventions that may be successful, although they 

do not directly affect income (39). These include 

programs that target high·risk groups; outreach pro· 

grams that include home visits; and programs that 

overcome barriers to the use of services by provid· 

ing transportation or convenient access and by using 

prompts and reminders. Large-scale multidisciplinary 

interventions involving a range of agencies and pro· 

grams may be cost-effective. The Special Supple· 

mental Food Program for Women, Infants and Chi!-

31 32 .. Rabin Hood Index 

Figuft 3. A~justed mortality In the Unjted Statti in 1990 •M tM ltobln Hood ihdex of income in~Ntuarey. C\'i'd!S r!'lpr-esent the natg of 

the UnMd S.tatM. Data were not ava1l.abkt tor New V..e-xn::o. Rl't¢CC !sl.tru:t d1'ld W9'f'llol Adapted from ~ned( and colleagu~ 1111 wth permJsstO!"! 

730 1 November 1998 • Annals of /ntem'fl Medicine • Volume 129 • Numbcr9 

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86 

Fig&.n 4.. LiM expectaMy at bkth .and ttot:t national product {GNP) in 1970 and 1995 In rich and poor countries in 1990 U.S. dollws.. Tn;tr:ql.e& 

leptll'5ent hfe exptctarw;y 4'1 1970, diolmond~ tepl'~t l1fe exp~tanq m l99S Data obt.J1ned from: World ~t lt\dl<:JitOtS, World SonK, 199S 

dren (WIC) was initiated in 1972 in the United 

States and provides healthy fond, education about 

nutrition, and health services to low-income women 

and their children. Data analysL< suggests substantial 

reduction.• in the number of babies with low and very 

low birth weights as a result ( 40). The project paid 

for itself through equivalent savings in medical care. 

Project Head Start provides preschool children and 

their families with education, health care. and social 

services. Short- and long-term benefits have been 

shown in health, developmental, and social outcomes (41). 

Economic analysis confirms that primary care interventions. including measures designed to reduce 

childhood malnutrition, improve immuni2ation against 

childhood diseases. provide chemotherapy against 

tuberculoois, provide condoms and education to combat the spread of HIV, and reduce smoking (including 

consumer taxes on tobacco) are cost-effective (42). 

Physicians Have Special Responsibilities 

disease and reduce mortality rates, a responsibility 

that ari•cs from their knowledge of medicine and 

medical practice ( 43). The physician-patient relationship is a fiduciary one, based on the inherent responsibility of physicians to deserve the trust of 

patients. Professionalism also extends this relationship to society. which confers on the profession 

respect and certain kinds of autonomy and authority. In the context of the physician-society relationship, the pbysician's fiduciary responsibility takes 

the form of concern for the public health. Most 

major traditions of medical ethics suggest that physicians have a special responsibility for the care of 

poor persons, defined as those who cannot alford to 

pay for treatment (44}. 

In addition, physician responsibilities in patient 

care extend to the social context of health and 

disease. Physicians regularly ancmpt to influence 

both patients' lifestyles and their environments to 

help prevent illness. They do so becau....: illness is 

often prcdpilated by behavioral and social factors. 

Physicians in practice have an obligation to act on 

behalf of the general public welfare (for example, 

It is widely accepted that physicians have a spe- by reporting infectious diseases to the proper aucia! and central professional responsibility to treat thoritics}. Recently, it ha.• become widely accepted 

1 November 1998 • Annals of lnt~nw.t Medicine • Votume 129 .. Number 9 131 

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87 

that physicians should work to promote smoking 

cessation, encourage use of seatbelt~. and prevent 

firearm injury. Health hazards should not he ruled 

oul as medical concerns because their remedy requires social or political action. Although the 

proper form and extent of political involvement for 

physicians may at times be controversial. -concern 

for the health of the public has been an important 

responsibility of the medical profession at least 

since the Industrial Revolution (45). 

II may he argued that although physicians have a 

responsibility to care for persons who are ill even 

though they are poor and cannot pay. medicine has 

no particular responsibility with respect to the gen· 

eral condition of poverty. Physicians' efforts to mit· 

igate poverty may be seen as going beyond the 

bounds of the patient-physician relationship. How· 

ever, efforts against poverty may have parallels in 

widely accepted attempts by physicians to prevent 

child abuse or health hazards in the workplace. 

Although patients may not ask to he protected from 

toxins or abuse, physicians have agreed that they 

have a responsibility to assist patients who may be 

in danger and, when possible, to prevent harm. If 

poverty is connected to ill health in a direct and 

powerful way, it can be argued that physicians have 

some degree of responsibility for addressing poverty 

itself to the best of their ability. 

Physicians Can Help Mitigate the Health 

Inequalities Caused by Poverty 

A panel convened by the King's Fund of London 

recently proposed four types of interventions to cor· 

reel health inequalities related to poverty: addressing social and economic factors; reducing barriers to 

the adoption of healthier ways of living; improving 

the physical environment; and improving access to 

appropriate. effective health and social services (46). 

Physicians have clear roles. to play in each of these 

elforts. 

Physician~ can address social and economic factors both on the level of the individual patient and 

on the level of the community. By being aware of 

socioeconomic factors. such as insurance status. ed.-

ucational background. occupational history, housing 

conditions, and social isolation. physicians can make 

more comprehensive diagnoses and tailor therapies 

to patients' needs. Unfortunately. in residency train· 

ing, the social history (if it is taken at all) is often 

labeled "noncontributory." Raik and colleagues (47) 

examined the content of resident case prcsentatiQns 

on inpatient rounds and found remarkably low rates 

of mention of socioeconomic factors. Physicians as 

teachers can addrcs.~ these factors on rounds and in 

describing their own patients to trainees and colleagues. 

On the community level, physicians can advocate 

for public policies to improve the health of the 

disadvantaged. Jarman ( 48) showed that physicians 

know that it is more complicated and takes more 

time to care for poor patients than for patients who 

arc not poor. With this evidence. he was able to 

persuade the National Health Setvice in the United 

Kingdom to take patient economic status into ac· 

count in rewarding general practitioners who work 

in deprived area.•. Given the growth of managed 

care in the United States, physicians should be at 

the forefront of those calling for poverty-based risk 

adjustments to capitated payments. 

As research scientists, physicians can advance the 

understanding of the mechanisms by which dcpriva· 

tion leads to ill health and the development of more 

effective intervention.< to reduce inequality in health 

( 49). Similarly, physicians who are aware of the 

adverse effects of international debt on health can 

urge debt relief for the poorest countries (50). 

Physicians may also be able to assist in removing 

barriers to healthy lifestyles-for example. cam· 

paigning against the promotion of tobacco, which is 

increasingly being targeted to adolescents in less 

developed countries and in minority communities in 

the United States (51). 

Physicians can aft'ect environmental factors associated with poverty by advocating for legislation to 

maintain and improve the quality of air, drinking 

water, and food. Physician-led public health efforts 

in the United States have been instrumental in reducing the incidence of lead poisoning, which is 

strongly associated with poverty. Internationally, 

physicians are participating in local initiatives surrounding Agenda 21, developed at the 1992 Earth 

Summit in Rio de Janeiro, Brazil. More than 1300 

local communities in 31 countries have developed 

their own action plans, many of which feature 

health issues. Through the WHO Healthy Cities 

Project, cities have addressed such issues as smok· 

ing. sanitation, air pollution, and socioeconomic differences in health (52). 

Approaches to improving access to effective 

health and social services in the United States and 

elsewhere have been extensively reviewed (39, 53). 

However, more than 800 million persons lack access 

to health sen.ices worldwide. and the increasing imposition of user fees (co payments and deductibles) 

in many countries has exacerbated inequities in care 

(54). Physicians and their associations should lead the 

movement for universal access to health care (55). 

An international meeting on health and poverty 

hosted by WHO and Action in International Mcd· 

icinc (which has approximately 100 affiliated organizations in more than 30 countries) urged assoda732 l November 1998 • Anrurlt" of lntt>mal MedidM • Volume 129 • Number 9 

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88 

tions of health professionals to engage in activities 

to reduce health inequalities due to poverty (56). 

Dr. Gro Harlem Brundtland, the newly appointed 

Director General of WHO, has indicated that she 

intends to make the reduction of ill health due to 

poverty a priority for her term of office (57). The 

United Nations Declaration of Human Rights in· 

eludes access to the basic necessities of life, such as 

food and water. as well as health care. However, 50 

years after the Declaration was written. we are still 

far from providing this access to everyone. Physi· 

cians have an important role to play in helping to 

tran.'lform the rhetoric of the Declaration into reality. 

RtqualS for l«ptints: Mit:hael McCally, MD, PhD, Department 

of Cornmuttity and Preventive Medicine.~ 1043, Mount Sinai School o( Medicine. New York. NY 10029; e-mail. mm6@doc 

.rnu.ntcdu. 

CuJttlll Author Ad.drtms.· Or. McCaHy: Depanmem of Commu· nity and Preventive Medicine, Box 1043, Mount Sinai School of 

Medicine., New York. NY 10029. Dr. Haines: Department of Primary Care and Population Sci· 

en~. Royal Free and Cnivcrsit)' College: Schools or Medicine, 

Routand Hill Street. London, NW3 2PF. United Kingdom. 

Dr. Fein: Come11 UniYcnity Medical College, 1300 York Avenue, Box 571. New York, NY 10021. 

Dr. Addington: Primary Care Institute. Rusb School of Medicint". 

1653 Wts:t CongteM; Parkway. Suite 807 Kicts.on. Chiatgo.. IL 60612. 

Dr. lawrence: Professional Education and Progt31ll$, Johns Hop- kins School o! 'Pulllic Health, 615 ~orth Wolfe Street. Room 205, 

Baltimore. MD 21218. 

Dr. Ca55el: Department of Geria1rics and Adull Development. 

Mounr Sinai Sct\ool of ~dicine, New York. NY 10029. 

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~ VM:. A.rldl« Books, lW, 

42, .Mm!S«t DT, MoMty WM.. .......nom Alt. lobadlh J, eds. O~.Me- Con. 

trol f'rtOI'>'tles m ~fl9 CountrieS A Summary Wasl'm'lqtot>. OC World 

9~. 1993 

Q. tonHn AR. JMMtcn AJ. Social .and poj!t!Uf ~bdif1es ol !Jhr>.<~M~$ 

J Met!~ 1971,2 376-400 

44. An:!.undsen OW, H!S1ary of m!O«I«thio. ln: E~ Ill IJ«:I'Hn New 

Yori: Mllct .. M,m; lWS 1$22·lli 

45. Rosan G. from ~JCat ~e to Sooat Ut'dJCI!'llr i'~ (11'1 IN! Hi}t\'ll'y ~ 

HHI~h Citt~ Ntw VQI'fl:· Sc·~ Htnoty E\bbcatKJnS; 1974 

ol&. leftnval M. Judv«-IC, Wh~ M, ... TM:k.IINJ 1n~hbM '"~!ttl 

An~ for Actoo lo!'4oo: K1og's Fund,. 199S 

47. Raikl.'-inO,WI~S. ~tlf\9!ht-\Mofpopv!all()O~t~ 

(M'! 1n1tm.lf ~lite attendltlg101>f!<ft. Acad Med 1995,70 1047·9 

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1983,286 170$·9 

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t No,·ember 1998 • Annals of lntemal1\ledir;int • Volume 129 • Number 9 733 

Downloaded From: http:/lannals.orgl by Tim Franquist on 06/11!2018 
89 

Timothy S. Franquist 

Mr. Franquist was appointed the Arizona Department of Environmental 

Quality's Air Quality Director in May 2016. He previously served as the Air 

Quality Division deputy director from November 2014 through May 2016. 

Since becoming director, Franquist has led Air Quality's effort to become 

nationally recognized for the agency's work on international transport of 

ozone, exceptional event demonstrations, permitting, and air quality 

meteorology. 

Franquist has been with ADEQ for more than 14 years, 12 of which he served in air quality. Prior to State 

service, Franquist worked in a variety of environmental positions, including private sector consulting, 

county government, and environmental non-government organizations. 

Franquist received his bachelor's degree in Environmental Science and Policy from The University of 

Maryland and his master's in Environmental Management from Arizona State University. 
90 

Mr. NORMAN. Thank you, Mr. Franquist. 

I now recognize Dr. Craft for her testimony. 

TESTIMONY OF DR. ELENA CRAFT, 

SENIOR HEALTH SCIENTIST, 

ENVIRONMENTAL DEFENSE FUND 

Dr. CRAFT. Thank you. Chairman Biggs, Ranking Member 

Bonamici, and Members of the Committee, thank you for the invitation to be here to testify regarding the National Ambient Air 

Quality Standards for ground level ozone. 

My name is Elena Craft. I serve as a senior scientist at Environmental Defense Fund, a national nonpartisan, science-based environmental organization where I manage a team working to identify 

strategies and opportunities to reduce harmful air pollution, such 

as ozone, from pollution hotspots. EDF is a national organization 

with over two million members that links science, economics, law, 

and private sector partnerships to solve our most serious environmental challenges. 

EDF and its members are deeply concerned about harmful air 

pollution, including ground level ozone. I am lucky enough to be 

joined today by a few moms from Moms Clean Air Force. Nationally, Moms Clean Air Force is a community of over a million moms 

and dads strong. They are mobilizing and engaging communities 

across the country on air quality issues because they care about 

their kids. They care about the tiny lungs that are developing. 

They care about making sure that their kids make it to school instead of to the doctor’s office or to the hospital because of an asthma attack. They care about the long-term health implications of 

living in areas that don’t meet health-based standards, standards 

supported fervently by doctors and public health professionals 

across the nation. 

Fortunately for almost 50 years, the Clean Air Act has provided 

bipartisan, time-tested solutions for reducing harmful pollution and 

protecting public health. National Ambient Air Quality Standards 

for deadly pollutants like ground level ozone form the foundation 

of the Clean Air Act’s health-based protections. These bipartisan, 

consensus-backed standards save lives and protect American families. 

But they are under threat. EPA Administrator Scott Pruitt is attempting to rescind, weaken, or delay many of these clean air 

standards. For instance, the Administrator has opened a loophole 

for super polluting, heavy duty long haul trucks. These glider vehicles are not required to deploy same modern pollution controls as 

other new long haul trucks. Gliders emit 43 times as many NOx, 

or nitrogen oxides, during highway driving than trucks with modern emission control systems. Allowing this loophole has resulted 

in significant increases in NOx. One years’ worth of glider sales accounts for more NOx emissions than all of the emissions generated 

as a result of the VW emissions billion-dollar cheating scandal. 

The Administrator has likewise neglected his responsibility to 

ensure protections are in place for downwind States and communities. For examples, the States of Connecticut, Delaware, and 

Maryland all submitted Good Neighbor petitions to EPA under Section 126 of the Clean Air Act, seeking relief from upwind emissions 
91 

from coal-fired power plants that cause health-harming ozone pollution within their borders, pollution that forms some of the background that you’ll hear about today. 

Ozone does not discriminate. No matter where it comes from, the 

effect on the human body, on our kids’ lungs, is the same. If we 

are in agreement that we value clean air, that we want our kids 

to breathe air that meets health-based standards recommended by 

the public health and medical communities, then the fastest way 

to achieve that clean air is to deploy the controls and policies that 

we know work. The controls that for almost 50 years have reduced 

aggregate pollution in our country by 73 percent, while GDP has 

grown 253 percent. 

Most of our country, including the San Antonio area, and all of 

Arizona, is expected to be in attainment with the 2015 Ozone 

standard by 2025 because of strong Federal policies, like the clean 

car standards, the clean power plan, and the cross-state air pollution rule. 

If we are serious about fulfilling the bipartisan agreement that 

serves as a bedrock environmental protection for our nation, then 

we must protect these policies and we must continue to support the 

scientific process that serves as the foundation for developing them. 

While there may be some challenges associated in isolated areas of 

the West, far and away, we should be more concerned with the current Administration’s egregious attack on policies that will deliver 

tens of thousands of tons of emission reductions and that are critical in helping all communities across the country meet healthbased standards. The Clean Air Act is important in reducing hospital visits, saving lives, and reducing healthcare costs. 

Thank you for the opportunity to be here. 

[The prepared statement of Ms. Craft follows:] 
92 

Before the United States House Committee on Science, Space, and Technology 

Subcommittee on Environment Hearing- State Perspectives on Regulating Background Ozone 

Testimony of Elena Craft, Ph.D. 

Senior Scientist 

Environmental Defense Fund 

June 21, 2018 

Chairman Biggs, Ranking Member Bonamici and Members of the Committee, thank you for the 

opportunity to testify regarding the National Ambient Air Quality Standards (NAAQS) for 

ground-level ozone. 

My name is Elena Craft. I serve as a Senior Scientist at Environmental Defense Fund (EDF), a 

national nonpartisan science-based environmental organization, where I manage a team working 

to identify strategies and opportunities to reduce harmful air pollution such as ozone from 

pollution hotspots. EDF is a national environmental organization with over 2 million members 

that links science, economics, law, and private-sector partnerships to solve our most serious 

environmental challenges. In addition, I have an adjunct appointment at the University of Texas 

Health Sciences Center School of Public Health in Houston and I am also a Kinder Fellow at 

Rice University. 

EDF and its members are deeply concerned about harmful air pollution, including ground-level 

ozone, and I greatly appreciate the opportunity to testify on these critical public health 

protections. 

I. An Extensive Body of Scientific Evidence Demonstrates that Ozone Pollution Harms 

Human Health 

Ground-level ozone, a component of smog, is a harmful air pollutant that irritates the lungs, 

exacerbates lung conditions like asthma, and is linked to a wide-array of serious heart and lung 

diseases. Scientific evidence spanning several decades shows that human exposure to ozone can 

cause a broad range of respiratory effects, including inflammation of the airways, asthma attacks, 

chronic obstructive pulmonary disease (COPD), and other health harms that can lead to increased 

use of medication, school absences, hospital admissions, and emergency room visits. 1 

EPA has estimated that the 2015 ozone standard will save hundreds of lives, prevent 230,000 

asthma attacks in children, and prevent 160,000 missed school days for children each year.2 

Between 2008 and 2015, there were more than 1,000 new studies that further confirmed the 

already well-documented health and environmental harms associated with ozone.3 In particular, 

EPA concluded: 

1 EPA, Integrated Science Assessment for Ozone and Related Photochemical Oxidants, Executive Summary (20 13), 

available at https://www.epa.gov/isa/integrated-science-assessment-isa-ozone-and-related-photochemical-oxidants 

(last visited Apr. 27, 2018). 2 EPA, Regulatory Impact Analysis of the Final Revisions to the National Ambient Air Quality Standards for 

Ground-Level Ozone, EPA-452/R-15-007, at ES-16, tbl.ES-6 (2015). 
93 

Scientific evidence shows that ozone can cause a number of harmful effects on 

the respiratory system, including difficulty breathing and inflammation of the 

airways. For people with lung diseases such as asthma and COPD (chronic 

obstructive pulmonary disease), these effects can aggravate their diseases, leading 

to increased medication use, emergency room visits and hospital admissions. 

Evidence also indicates that long-term exposure to ozone is likely to be one of 

many causes of asthma development. In addition, studies show that ozone 

exposure is likely to cause premature death.4 

Very recent evidence from studies published within the last year further solidifies the link 

between ozone exposure and an increased risk of death. One key study assessed ozone impacts in 

61 million Medicare beneficiaries across thirteen years in the United States and found that the 

risk of death associated with ozone exposure continued below the current 8-hour NAAQS 

standard of 70 parts per billion (ppb).5 The authors of this landmark study concluded that there 

was no threshold below which exposure to ozone did not produce adverse health consequences.6 

Another study found that long-term seasonal ozone was also associated with premature mortality 

and that reduction of just 5ppb of summertime average ozone across the country would save 

9,537 lives per year.7 

This body of scientific and technical literature also demonstrates that the risk of these harmful 

health effects is even more pronounced for people with asthma and other respiratory diseases, 

children, older adults, and people who work or are active outdoors. An estimated 20 million 

people over the age of 18 have asthma in the U.S. and an estimated 6.1 million children under 

the age of 18 have asthma.8 Asthma disproportionately impacts communities of color and lowerincome communities.9 

Children, in particular, are considered the most at-risk group because they breathe more air per 

unit of body weight, are more active outdoors, are more likely to have asthma than adults, and 

are still developing their lungs and other organs. In fact, EPA's Children's Health Protection 

Advisory Committee (CHPAC)-a body of external experts that provides the Administrator with 

recommendations concerning children's health- recommended a substantially stronger standard 

3 EPA, Fact Sheet, Overview of EPA's Updates to the Air Quality Standards for Ground-Level Ozone ("2015 Ozone 

Standard Fact Sheet"), available at https://www.epa.gov/sites/production/files/2015-

IO/documents/overview of 2015 rule. pdf; see also EPA, Integrated Science Assessment for Ozone and Related 

Photochemical Oxidants, Final Report (Feb. 2013), available at 

http://cfpub.epa.gov/ncea/isa!recordisplay.cfm?deid=247492#Download. 

' 2015 Ozone Standard Fact Sheet. 5 Di Q, Dai L, Wang Y, Zanobetti A, Choirat C. Schwartz JD, Dominici F., Association of Short-term Exposure to 

Air Pollution With Mortality in Older Adults, 318 JA,\1A 2446-2456 (2017), doi: 10.1001/jama.2017.17923 6 Id. 

7 Di, Q., Wang, Y .. Zanobetti, A .. Wang. Y., Koutrakis, P., Choirat, C., Dominici, F. and Schwartz, J.D., Air 

pollution and mortality in the Medicare population. 376 NEW ENGLAND J. OF MED., 2513-2522 (2017), available at 

http://www.nejm.org/doi/fullll O.l 056/NEJMoa 1702747. 8 Centers for Disease Control and Prevention, National Center for Health Statistics, 2016 available at 

https://www.cdc.gov/nchs/fastats/asthma.htm 

9 Id. 

2 
94 

to protect the health of children. CHPAC found that "[c]hildren suffer a disproportionate burden 

of ozone-related health impacts due to critical developmental periods of lung growth in 

childhood and adolescence that can result in permanent disability." 10 

Implementing the strengthened ozone health standard is essential to begin addressing the health 

harms that children, sensitive populations, and all Americans face due to ozone exposure. 

II. Millions of Americans Are Exposed to Unhealthy Levels of Air Pollution 

Nationwide, millions of Americans are exposed to unhealthy levels of air pollution. A recent 

report by the American Lung Association (ALA), State of the Air 2018, which looked at air 

quality from 2014 to 2016, found that ozone pollution "worsened significantly" compared to the 

prior year's report. 11 The American Lung Association notes that from 2014 to 20 16 "more than 

133.9 million people live in the 215 counties that had unhealthy ozone or particle pollution."12 

And of the report's top twenty-five areas for unhealthy levels of ozone pollution, some 

improved, but sixteen had worse ozone from 2014 to 2016, 13 which underscores the importance 

of implementing the more protective, 2015 ozone standard. 

Figure 1, below, shows the American Lung Association's list of the twenty-five areas across the 

country that face the highest levels of ozone pollution, which demonstrates that these heavilypolluted areas are not limited to any specific geographic area. 14 

10 Letter from Sheela Sathyanarayana MD MPH, Chair, Children's Health Protection Advisory Committee to 

Christopher Frey PhD, CASAC Review of the Health Risk and Exposure Assessment for Ozone and Policy 

Assessment for the Review of the Ozone NAAQS: Second External Review Drafts, (May 19, 2014), available at 

https://www.epa.gov/sites/production/files/20l4-l2/documents/20 14.05.19 chpac ozone naags.pdf. 11 American Lung Association, State of the Air 2018, Key Findings, available at http://www.lung.org/ourinitiatives/healthy-air/sotalkey-findings/ 

12 /d. 13 /d., Ozone, available at http://www.lung.org/our-initiatives/healthy-air/sotalkey-findings/ozone-pollution.html. 14 /d. at 20, available at http://www.lung.or•/assets/documents/healthy-air/state-of-the-air/sota-2018-full.pdf. 

3 
95 

FIGURE 1: People at Risk in 25 Most Ozone-Polluted Cities 

People at Risk In 25 Most Ozone-Polluted Cities 

,. .. - ...... - _,. 01 

RaftkS ~SbdstkaiAreas - ....... ,., .,_. ....... » ....... » COI'O' ,.._. 

1 lm-·'-lleach.CA 18.688,022 4.353.354 2.444.450 334.698 1,119.385 628.200 7,942 1,433,318 - 2 -CA 884.788 258.054 91,719 19.840 48.388 25.731 Jn 57,988 

3 VlSalia-~HanfoJd. CA 610.222 184.746 64,88'> 14.204 32,845 17.612 260 39.595 

~CA 1.134.612 323.002 136.983 24.836 62.984 34,873 482 78.731 

Sacramento-Poseviae. CA 2.567,451 595,320 389.039 45.710 155.308 91.493 1.090 209,852 

6 S.O-CA 3.317.749 728.325 446.008 55.996 201.462 112.570 1.413 254.999 

7 -CA 810.232 227,322 98,506 t7.4n 45,364 25.251 345 57.294 

Phoenix·Mesa-Scoc:tsd*, AZ 4,661,537 1.138,270 703,512 91.762 331.403 233,308 2.213 373.254 

Red<ling-RedBiuff,CA 242,907 53.835 48.295 4.139 15.160 9.825 103 22.749 

10 New York-Newark. NY--NJ·CT-PA 23,689,255 5.145.013 3539.645 458.494 t,nt.736 1.038.329 13.759 1.826.564 

11 Houston-The Woodlands. TX 6,972.374 1.860.373 739.774 147.214 389.479 241,094 3.688 550.064 

12 Las--NV-AZ 2.404.336 551.082 374.922 36.391 150.570 129,535 1.242 205.979 

13 SMI..Iose-San Francisco-Oakland, CA 8,751.807 1.874,550 1.250.653 144.121 539,410 309.563 3.721 708.929 

14 ,_._co 3.470.235 803.223 427.601 64,700 234,863 112500 1,483 167,799 

15 BCentro.CA 180,883 51.832 22.953 3.985 1Q037 5,646 n 12,757 

16 Dallas-Fort Worth. lX..()f( 7.673.305 2016.215 862,921 159,749 432.736 273.449 4,058 624.821 

17 WAshington-Ebltimore-Arlington. OC·MO·VA·WV·PA 9.665,892 2,205,657 1.282.504 199530 tn2,877 423.744 5,526 762909 

18 s.ltW.Gty-~.UT 2,514,748 765,804 241,347 44,no 145,432 66,492 654 122.337 

19 R>rtColfiro.CO 339.993 68.025 50,096 5.479 23.835 11,703 145 17.434 

20 Hartfoni..WestHartfoo':I.CT 1.476,637 301,063 243.852 33.160 123,604 69,574 887 115.420 

21 Chico,CA 226,864 45,489 40,815 3.497 14,.266 8.676 96 19.679 

22 Chic.Jgo-NapeMDe.ll-IN-WI 9,882.634 2.300,124 1.348.267 170.477 683,5<>0 473,577 6.620 775,469 

23 -Aillens-a..t<eCoonty--s.ndySpring>,GA 6.451.262 1.606.983 760,202 142,134 420,082 367,638 4.100 572.742 

24 Phitadelptja-Re3ding-C.amden. PA-NJ·DE·MD 7.179.357 1.583.881 1.110.738 135,570 550,637 380.103 4,487 572192: 

24 -WI 115.427 25,986 19.797 2.159 7,662 5.385 .. 9,052 

l Gbts-~u:Ml~~~-.lor.any<oontyWlttl>nlh.l!Comb!l'le<IMwopolrbn5t;ltistM:aiAINOfM!.Itq:IOiitanSbt>stiQIAtN. 

2.1ilc::lli~~tho;ot-6$Jt~sforollcountiesw•lt>inth.o-pectlvt!Coml>intld~t>~~>Sbtln•ui/J,ru<W~l»lSbtt!.tiaiM<l. 

3. Tllo$e'IIIWier1&Md65...:11--~~toPM,~...U-.~fu<e.a"~Theyshoub:lnM:be<>$«1"''~den<>m~klr~--<!S. 

4-Piedi;;a&ric.asdle»~-.fof~.-.,taV"iir><Jfap!;Jndr~tt!WI~"""'bo!rof~wtx>hOJd~th""'in20l4~....,stale~(9RFSS)appl!edtopDIIUbtioontlmales!US.~I 

S..Ad..-.asnu-;ntortbowl8,e.m.<WtdolderJIId~tht!~flunoberofP!!OPiewt.ohlld~~lfl2016bil~<.>n•~rat6(8RFSSJ~to~estJm.lles(US.Cem.usl. 

6 ~~-.m...nm""""""I!''O:lid ... timlit~ Mdiflgt!'oo!,;Sw-c'*~f:><ltomaCOPO . ..tc)w.ll~llll~whotullf!'""""ofuant><P.dwithiiWPlb.WION'~ 

7 COPO~.-f«DftsUIM!d_....t>o~bftn~within!heir~le~.botsl!'donsut:er~tBRFSSl~topopubtl<.>n~~{U.S.C~. 

ll. CV~is~.ncuAior~;ll'ldntirrates;nfof .xtulb lS~rniiN~rwhohave~cha1!J"''S<1dwilflifotht-or~fetime.b.l~on$~0'ratf'!l18RFSS)appfll!'dto~tiooe:UiiNIM{US. Cef>ws). 

'1 ~~WR!fromlhf'US.C.,..-~.md-lot;lll"'tf''i. 

Source: American Lung Association, State of the Air 2018, available at 

http://www. lung.org/assets/documents/healthy-air/state-of-the-air/sota-20 18-full.pdf 

In my home state of Texas, State of the Air 2018 found there were over 400 orange, red, or 

purple high ozone days (denoting specific ranges of severity for adverse health outcomes) in the 

counties examined in the report from 2014 to 2016. Fourteen counties received a grade ofF in 

Texas for ozone pollution. 15 

San Antonio, Texas is one of several areas in my home state that is particularly at risk. EPA has 

still not determined whether air quality in the San Antonio area meets the 2015 standard, despite 

the fact that monitors in the area have exceeded the 70ppb design value for many years. While 

EPA unlawfully delays, the citizens and children of San Antonio suffer the consequences as we 

15 ld. at 152. 

4 
96 

move toward the height of summer ozone season. State of the Air 2018 estimates the number of 

individuals from these sensitive populations living in the San Antonio area. Among other 

sensitive groups, the report estimated that over 58,767 children suffering from pediatric asthma 

and 168,266 adults suffering from asthma live in the eight counties in the San Antonio area. 16 

The report projects that there are 109,ll3 individuals suffering from COPD, 171,929 individuals 

suffering from cardiovascular disease, and 1,524 suffering from lung cancer also live within 

those eight counties. The report ranked the San Antonio-New Braunfels area twenty-seventh for 

high ozone days out of 227 metropolitan areas. By failing in its duty to determine whether the 

San Antonio area meets the 2015 standard, EPA is unlawfully delaying needed air pollution 

protections for this region. 

Other areas across the country, including in the Intermountain .West suffer from elevated levels 

of ozone pollution. For instance, two areas in Arizona are on ALA's top 25 most ozone polluted 

areas. EPA re~orts the Phoenix-Mesa-Scottsdale area had thirty-one days of unhealthy ozone 

levels in 2016. 7 

FIGURE 2: Number of Days Reaching Unhealthy for Sensitive Groups in 

Phoenix-Mesa-Scottsdale, AZ 

Phoenix-Mesa-Scottsdale, PZ. 

103 

::moo 2001 2002 2·'J01 ~oo4 zoos :-oos ::-oo; 2':>JB 2oos ::Jto 20! 1 :,;.;c 2013 ::014 2o1s 2016 

Source: 

Air Qual1t; lndex Categor} 

• Vert Unhealtliy 

-Unllealth·1 

• Unhealth't for Sensltl'.te Groups 

https:/ /gispub.epa.gov/0 AR OAOPS/SeasonReview20 16/index.html ?appid-81 efd40 145584349a40b0869e20ffc3d 

Indeed, though summer ozone season is just beginning across much of the country, there have 

already been a number of alerts for high ozone pollution, including in Arizona, Pennsylvania, 

and Texas (see the appendix of alerts issued or reported as of June 13, 2018). 

16 The eight Texas counties for which EPA has not made a final area designation include: Atascosa, Bandera, Bexar, 

Coma!, Guadalupe, Kendall, Medina, and Wilson. 17 US EPA, A look back: Ozone in 2016, available at 

https:/ /gispub.epa. gov/0 AR OAOPS/SeasonReview20 16/index. htm1 ?appid-81 efd40 145584349a40b0869e20ffc3d 

5 
97 

III. Bipartisan, Time-Tested History of Clean Air Act's Health-based Standards 

Fortunately, for almost 50 years, the Clean Air Act has provided bipartisan, time-tested solutions 

for reducing harmful pollution and protecting public health. National Ambient Air Quality 

Standards for deadly air pollutants like ground-level ozone form the foundation of the Clean Air 

Act's health-based protections. These bipartisan, consensus-backed standards save lives and 

protect American families. 

The Clean Air Act establishes a carefully-calibrated structure which provides for two distinct 

phases for setting or updating these vital standards. First, EPA is charged with establishing a 

health-protective standard. These standards are informed by an extensive volume of peerreviewed literature as well as by a panel of scientific advisors. Following the establishment of 

these standards, a separate implementation process rooted in cooperative federalism takes place, 

whereby EPA works to carry out the NAAQS program in conjunction with the states and local 

air quality regulators. 

The language crafted by Congress in 1970 is straightforward. It instructs EPA's Administrator 

to, first, establish standards that "are requisite to protect the public health" with "an adequate 

margin of safety." 18 The statute is clear that the standards be set based exclusively on public 

health considerations and to be precautionary in safeguarding against adverse health effects. As a 

matter of Congressional design, the level at which the standards are set is to be based on public 

health considerations alone. The question of what factors may be considered in the standardsetting process has also been consistently answered by the decisions of prior EPA Administrators 

and numerous judicial decisions of the federal court of appeals in Washington, D.C., as well as 

by the U.S. Supreme Court19 

Ultimately, this question was emphatically answered by a unanimous Supreme Court. Justice 

Antonin Scalia, writing for the high Court, explained that the text of the Clean Air Act is clear in 

that only public health factors may be considered. Justice Scalia then set forth .the inquiry the 

Administrator must make in establishing the nation's health-based air quality standards-one 

that is thoroughly anchored in protecting public health: 

The EPA, "based on" the information about health effects contained in the 

technical "criteria" documents compiled under § 108(a)(2), 42 U.S.C. § 

7408(a)(2), is to identify the maximum airborne concentration of a pollutant that 

the public health can tolerate, decrease the concentration to provide an "adequate" 

margin of safety, and set the standard at that level. Nowhere are the costs of 

achieving such a standard made part of that initial calculation.20 

After the health-based standard is established, the Clean Air Act then provides a prominent role 

for consideration of costs in national, state, and local decisions about the pollution control 

strategies deployed to achieve the standard. The statute provides for the consideration of costs in 

18 Clean Air Act§ 109(b)(l), 42 U.S. C.§ 7409(b)(l). 19 See, e.g., Am. Lung Ass'n v. EPA. 134 F.3d 388 (D.C. Cir. 1998); Natural Res. De[. Council v. Adm'r, EPA, 902 

F.2d 962 (D.C. Cir. 1990), vacated in part on other grounds, 921 F.2d 326 (D.C. Cir. 1991); Am. Petroleum Inst. v. 

Castle, 665 F.2d 1176 (D.C. Cir. 1981); Lead Indus. Ass'n, Inc. v. EPA, 647 F.2d 1130 (D.C. Cir. 1980);Whitman v. 

Am. Trucking Ass'ns, Inc., 531 U.S. 457,465 (2001). 20 Whitman, 531 U.S. at 465. 

6 
98 

setting emission limits for cars, SUVs, trucks, buses, construction equipment, aircraft, fuels, 

power plants, and industrial facilities. 

States and local governments, in tum, are distinctly responsible for designing the air quality 

management plans for their communities and entrusted with determining how the burden is 

allocated to restore healthy air. As Justice Scalia succinctly explained, "[i]t is to the States that 

the Act assigns initial and primary responsibility for deciding what emissions reductions will be 

required from which sources."21 

IV. EPA Strengthened the Health-based Standard for Ozone in 2015-An Action 

Grounded in an Extensive Body of Scientific Literature and that Enjoys Broad, 

Public Support 

This time-tested and bipartisan framework has delivered significant pollution reductions, all 

while the U.S. economy has continued to grow. EPA's most recent action to update the nation's 

health-based ozone standards, finalized in 2015, resulted in a more protective standard of 70ppb. 

EPA's action was grounded in the extensive body of scientific literature, described above, 

documenting that the previous standard of 75ppb was not requisite to protect public health. 

There is strong public support for the 2015 ozone standard. The American Lung Association 

conducted polling in April 2018 that demonstrated continued, cross-partisan, public support for 

the standard, noting: 

Three-quarters of voters support EPA enforcing these stricter limits on smogwith a majority of all respondents strongly supporting. In every demograph,i~ 

group polled, more voters supported than opposed enforcement of the standards.· 

Leading health and medical associations, including the American Lung Association, American 

Academy of Pediatrics, American Public Health Association, American Thoracic Society, Trust 

for America's Health, Asthma and Allergy Foundation of America, Health Care Without Harm, 

and National Association of County and City Health Officials, supported strengthening the 

previous, 2008 ozone standard.Z3 The American Academy of Pediatrics forcefully reiterated that 

"[o]zone pollution in the air disproportionately impacts children, whose unique health and 

developmental needs make them more susceptible to pol!utants."24 Community and 

environmental justice groups such as Voces Verdes and We ACT for Environmental Justice also 

supported lowering the standard.25 

21 /d. 22 American Lung Association Press Release, New Poll: Voters Overwhelmingly Support Stricter Limits on Smog. 

April24, 2018, available at http://www.lung.org/about-us/medialpress-releases/new-poll-smog.html 23 Comments from American Academy of Pediatrics et al. to the US Environmental Protection Agency, March 17, 

2015, available at http://www.lung.org/assets/documents/advocacy-archive/national-health-and-medical.pdf 24 American Academy of Pediatrics Press Release, AAP Statement on New EPA Ozone Standards, October 1, 2015, 

available at: https://www.aap.org/en-us/about-the-aap/aap-press-room/Pages/EPAOzonefinalstd.aspx 25 See V aces Verdes Press Release, Voces Praises New Proposed Limits On Ozone; Supports Health Protective 

Standard, November 26, 2014, available at: http://www.vocesverdes.org/voces-in-action/3636/voces-praises-newproposed-limits-on-ozone-supports-health-protective-standard; WE ACT for Environmental Justice, "Why WE ACT 

and its Allies Sued EPA for Cleaner Air," available at https://www. weact.org/20 171!2/act-allies-sued-epa-cleanerair/. 

7 
99 

The 2015 ozone standard also received broad support from elected officials at all levels, 

including a diverse coalition of seventy mayors representing communities from all across the 

nation. The mayors stated that the prior 75ppb standard was "widely acknowledged by the 

medical community as insufficient to protect public health."26 The letter went on to underscore: 

As local elected officials representing big cities and small towns, we want to 

express our strong support for the Environmental Protection Agency's (EPA) 

work to update the ozone (or smog) standard .... As mayors, we are on the front 

lines of protecting the safety and well-being of our constituents and this longoverdue update will reap tremendous benefits for our communities. 27 

V. The NAAQS Work and Are Achievable with Made-in-America Technology 

Solutions 

Many highly cost-effective, commonsense clean air measures are available to help secure 

pollution reductions needed to achieve the improved air quality standards. The 48-year history of 

the Clean Air Act shows that the nation's public health standards are achievable, through 

available technologies and innovation by states and businesses. The broad environmental 

technologies, goods, and services sector was a more than $1 trillion global market, with the U.S. 

providing exports of near! y $48 billion in 2015.28 

Moreover, our nation has often worked to achieve greater reductions than required, sooner, and 

at lower costs than estimated. Indeed, there are many clean air measures already underway that 

will help protect states, communities, and families from ozone pollution. EPA noted in its recent 

Air Trends report that most counties (outside of California) would be in attainment with the 2015 

ozone standard by 2025, stating that "[ f]ederal rules, including the Cross-State Air Pollution 

Rule, Mercury and Air Toxics Standards, the Tier 3 Vehicle Emissions and Fuels Standards, and 

the Clean Power Plan, will help reduce ozone-forming pollution in the years ahead." 29 

Other examples of reductions that will help meet the 2015 ozone standard include the costeffective standards to reduce emissions from the oil and gas sector. EPA's emissions standards 

for new and modified oil and gas sources are modeled after successful state programs in 

Colorado and Wyoming. In Colorado, for instance, state standards have helped to reduce 

equipment leaks by seventy-five percent, while oil and natural gas production has increased. 

26 Mayors Smog Letter to President Obama, (Sept. 21, 2015) available at 

https:l Isle green. files. wordpress.com/20 15109/mavors-smog -letter-final-copy-9-21-20 15 .pdf 

27 ld. 28 U.S. Department of Commerce International Trade Administration, 2017 Top Markets Report Environmental 

Technologies A Market Assessment Tool for U.S. Exporters (June 2017) at 2, 

https://www.trade.gov/topmarkets/environmental-tech.asp (last visited: June 19, 2018). The United States is the 

single largest market for the sector, which provided about $330 billion in revenue in 2016. Indeed, environmental 

technology is a robust industry sector in the U.S., employing 1.6 million people. For instance, the national average 

ozone level has gone down 31% since 1980 and more than 90% of areas originally designated nonattainment for the 

1997 ozone standards now meet those standards. Compare U.S. EPA, https:/lwww.epa.gov/air-trends/ozone-trends 

with U.S. EPA, By the Numbers Fact Sheet (Oct. 2015). https:l/www.epa.gov/sites/productionlfilesl2015-

1 0/documents/20151 001_bynumbers.pdf. 29 U.S. EPA, https://gispub.epa.gov/air/trendsreport/20161, (last accessed June, 12 2018). 

8 
100 

Nationally, EPA estimated these standards for new sources would reduce volatile organic 

compound (VOC) emissions by 210,000 tons in 2025. 

Additionally, there are numerous cost-effective, readily-available emission reductions yet to be 

implemented. For example, as evidenced in petitions to EPA from states like Maryland and 

Delaware, there are coal-fired power plants in several areas of the country that are not fully 

utilizing their already-installed pollution controls (e.g., selective catalytic reduction) to reduce 

ozone-precursor emissions of oxides of nitrogen (NOx). Left unaddressed, these units' emissions 

will continue to contribute to local and downwind ozone air pollution in places like Maryland 

and Delaware, creating challenges for communities to meet and maintain the NAAQS.30 

Lastly, more protective NOx controls for heavy-duty trucks can deliver important and highlycost effective pollution reductions from these vehicles. Heavy-duty manufacturers are 

developing new, effective solutions to reduce NOx emissions from trucks and buses. Advances 

in combustion and fuel injection systems, turbochargers, electronic controls, diesel particulate 

filters, and improved selective catalytic reduction (SCR) technologies are enabling reductions in 

NOx and other air pollutants.31 In addition, the South Coast Air Quality Management District 

(SCAQMD) in California worked with heavy-duty engine manufacturer Cummins to develop an 

ultra-low NOx emission compressed natural gas engine for freight trucks. 32 Electric-drive trucks 

are also a new avenue opening up to further reduce NOx and particulate matter (PM) emissions 

from heavy-duty trucks. Standards to implement these and other advanced technologies would 

deliver vital health protections and benefit communities nationwide. 

VI. The Trump Administration's Actions to Roll Back Clean Air Protections Threaten 

Human Health 

When it finalized the 2015 ozone standard, EPA determined that highly-cost effective clean air 

policies that were already on the books would help many areas meet the more protective ozone 

standard. Despite these important pollution reductions and well-established benefits, EPA 

Administrator Scott Pruitt is attempting to rescind, weaken, or delay many of these clean air 

standards. 

Standards Applicable to Major Stationary Sources of Pollution. Administrator Pruitt has 

sought to weaken protections applicable to major stationary sources of air pollution, including, 

for example, his proposal to repeal the Clean Power Plan. However, these critical standards will 

reduce carbon emissions from the power sector by thirty-two percent and will reduce NOx 

emissions by 278,000 tons in 2030. The combined ozone and particulate matter reductions the 

30 See State of Maryland Department of the Environment. Petition to the United States Environmental Protection 

Agency Pursuant to Section 126 of the Clean Air Act (Nov. !6, 2016), available at 

http:l/news.maryland.gov/mde/wp-contenUuploads/sites/6120 16111/MD _126_Petition_Fina1_111616.pdf. 31 See California Air Resources Board, Draft Technology Assessment: Lower NOx Heavy-Duty Diesel Engines 

(September 2015) at ES-8, http://www.arb.ca.gov/msprogltech!techreporUdiesel tech report. pdf. 32 See South Coast Air Quality Management District, et. al., Petition to EPA for Rulemaking to Adopt Ultra-Low 

NOx Exhaust Emission Standards for On-Road Heavy-Duty Trucks and Engines (June 3, 2016), available at 

http://www .aqmd.gov!homelnews-eventslcurrent -news/20 16-news-archi veslnox -petition-to-epa; see also C ARB, 

Draft Technology Assessment: Lower NOx Heavy-Duty Diesel Engines (September 2015) at ES-9 ("Cummins 

believes a 0.1 g/bhp-hr NOx level is feasible with some improvements to the current SCR technology and the 

conventional diesel combustion process while still allowing for fuel economy optimization.") With further 

improvements, the company believes NOx emissions could be reduced to 0.02 to 0.05 glbhp-hr levels. 

9 
101 

Clean Power Plan will deliver will help to avoid 3,600 deaths, 90,000 asthma attacks, and I ,700 

hospital visits in 2030. 

In addition, the Administrator has taken action to create new and dangerous loopholes in the 

Clean Air Act's New Source Review program. Without seeking public input, EPA has sought to 

make it easier for major, industrial sources of dangerous air pollution to make changes that 

would increase pollution from their facilities while avoiding the longstanding requirement to 

simultaneously deploy state-of-the-art pollution control technologies. 

The Administrator has likewise neglected his responsibility to ensure protections are in place for 

downwind states and communities. For example, the States of Connecticut, Delaware, and 

Maryland all submitted "good neighbor" petitions to EPA under section 126 of the Clean Air Act 

seeking .relief from upwind emissions from coal-fired power plants that cause health-banning 

ozone pollution within their borders. Those petitions ask EPA to ensure that these upwind power 

plants install-or, in the case of Maryland's petition, simply run already-installed-modem and 

cost-effective pollution controls. The Administrator has failed to respond to those petitions in 

the timeframes provided for under the law. As a result, in a judicial decision issued just last 

week concerning the State of Maryland's pending "good neighbor" petition, the court stated that 

it was "troubled by EPA's apparent unwillingness or inability to comply with its mandatory 

statutory duties within the timeline set by Congress."33 Unfortunately, EPA issued a proposed 

decision on June 8, 2018 indicating that it intends to deny the pending "good neighbor" petitions 

from Delaware and Maryland.>4 

Standards Applicable to Mobile Sources of Pollution. The Administrator has also proposed to 

weaken or rescind protections applicable to mobile sources. For instance, the Administrator has 

proposed to withdraw a rule for super-polluting heavy-duty, long-haul trucks, which would 

ensure that these "glider" vehicles deploy the same modern pollution controls as other new longhaul trucks. 35 Large freight trucks and buses are one of the largest sources of NOx emissions in 

the U.S., contributing to harmful pollution in communities across the nation.36 Removing 

protections for super-polluting "glider" trucks would result in significant increases in NOxaccounting for more NOx emissions than all of the emissions generated as a result of the 

Volkswagen emissions cheating scandal. 37 These NOx emissions would lead to the formation of 

ozone as well as increased particulate matter. Furthermore, if the Administrator moves forward 

with this rollback, by 2025, these super-polluting freight trucks would make up just five percent 

of the nation's truck fleet, but they would cause one third of the air pollution attributable to the 

fleet. 38 

33 Maryland v. EPA, Dist. Ct. of MD Case :"o!o. 17-2873, June 13, 2018 Memorandum at 14. 34 83 Fed. Reg. 26,666 (June 8, 2018). 35 U.S. EPA, Proposed Rule: Repeal of Emission Requirements for Glider Vehicles, Glider Engines, and Glider Kits. 

82 Fed. Reg. 53,444 (Nov. 16, 2017). 36 U.S. EPA, 2013 Final Report: Integrated Science Assessment of Ozone and Related Photochemical Oxidants at 3-

6, https://cfpub.epa.gov/ncea!isa!recordisplay.cfm?deid-24 7 492. 37 Comment ofEDF, ELPC, & WE ACT for Environmental Justice on EPA's Proposed Rule, Repeal of Emission 

Requirements for Glider Vehicles, Glider Engines, and Glider Kits, 82 Fed. Reg. 53,442 (Jan. 5, 2018), at 11-12, 

https://www .regulations.gov/document?D=EP A-HQ-OAR-2014-0827-4861. 38 U.S. EPA, Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and 

Vehicles-Phase 2; Final Rule, 81 Fed. Reg. 73,478, 73,943 (Oct. 25, 2016); see also HDP2 Response to Comments 

Section 14 Appendix A. 

10 
102 

National Ambient Air Quality Standards. The Administrator has also taken actions designed 

directly to weaken the National Ambient Air Quality Standards, including, for example, 

unlawfully delaying implementation of the 2015 ozone standard. In response to a lawsuit filed by 

states and public health and environmental organizations, EPA has now moved forward to 

identify certain areas of the country that do not meet the 2015 standard. However the agency's 

action comes almost an entire year after it was due, meaning that communities with unhealthy 

levels of ozone will face another summer without solutions in place to clean up the air. In 

addition, EPA has yet to take any final action concerning the eight counties around San Antonio, 

resulting in delays of the health and air quality protections the Clean Air Act provides. 

Moreover, Administrator Pruitt has determined that certain areas meet the national standards 

despite monitoring data to the contrary. The Administrator has disregarded some of these 

monitoring data on the grounds that the unhealthy levels of ozone pollution are the result of 

exceptional events. The Clean Air Act, however, provides only very narrow circumstances under 

which EPA may do so, animated by the Act's strong focus on the protection of public health. A 

recent Presidential Memorandum to Administrator Pruitt turns the exceptional events provision 

on its head by encouraging states to submit these demonstrations to EPA as a routine matter. In 

the wake of this memorandum, EPA has now relied on a series of purported exceptional events 

to remove counties from traditional area boundaries when setting the final nonattainment areas. 

Finally, Administrator Pruitt has issued a memorandum broadly addressing implementation of 

the National Ambient Air Quality Standards program. Among other deficiencies, the memo 

implies that EPA might consider costs when setting the NAAQS, despite settled Supreme Court 

precedent that the standards must be based on public health considerations alone. 

*** 

These are just a few examples of highly cost-effective policies to reduce ozone pollution that are 

under threat by the Administrator's actions. 

VII. Man-made Emissions Sources Continue to Play the Largest Role in Unhealthy 

Ozone Levels 

Eliminating the above-described protections is deeply misguided and would result in additional, 

harmful air pollution in communities across the country, while removing important tools from 

state air quality planners who are working to restore healthy air. This is especially so because, as 

EPA recognized when adopting the 2015 ozone standard, the anthropogenic sources addressed 

by these clean air measures are the dominant contributors to unhealthy ozone levels. 

Notwithstanding this finding, Administrator Pruitt has expressed an intent to reexamine the 

contribution of "background ozone" levels to violations of the NAAQS. However, EPA has 

already examined these issues in its Policy Assessment for the review of the 2015 ozone standard 

and again in a 2015 White Paper on Issues Associated with Background Ozone. Both times, the 

agency concluded that anthropogenic emissions sources are the dominant contributor to most 

modeled ozone exceedances of the NAAQS nationally and within individual regions across the 

ll 
103 

country. 39 In particular, when ozone levels are at their highest, anthropogenic sources are 

significant contributors, and these sources can be effectively addressed. 

A recent peer-reviewed publication from the Cooperative Institute for Research in 

Environmental Sciences supports these findings. That study examined the oil and gas sector's 

contribution to ozone formation on Colorado's Front Range, focusing specifically on days that 

exceeded the ozone NAAQS. The study found that, on individual days, oil and gas ozone 

precursors could contribute in excess of 30 ppb to ozone concentrations and could be the primary 

driver of exceedances of the ozone NAAQS in that region.40 Another study of the Colorado Front 

Range found that oil and gas VOC emissions contributed approximately twenty percent to 

regional ozone production. 41 

These findings underscore that, even in areas across the Intermountain West where background 

levels are sometimes incrementally higher, anthropogenic sources are substantial contributors to 

exceedances of health-based standards and that there are available solutions to reduce this 

harmful pollution. Furthermore, EPA has tools in place to address rare instances when truly 

exceptional events impact air quality, and western and southwestern states including Texas,42 

Arizona,43 and Wyoming,44 have previously sought to use these provisions. 

VIII. Conclusion 

This hearing is held under the auspices of the House Committee on Science, Space, and 

Technology. With that in mind, it is science that informs us on how to best manage the health 

harms of air pollutants like ozone. A rigorous and extensive body of science demonstrates the 

health harms that occur because of exposure to ozone pollution. Fortunately, as Americans, we 

have been able to rely upon the Clean Air Act, forged on a bedrock foundation of bipartisan 

collaboration for our nation, to protect against these health harms. But these protections are 

under threat. We need leadership and cooperation from our representatives and public officials in 

employing common sense solutions to ensure that our nation has a vibrant economy and a 

healthy environment. If we continue to work together building from this legacy of bipartisan 

39 Policy Assessment for the Review of the Ozone National Ambient Air Quality Standards (hereinafter Policy 

Assessment) Chapter 2 and Appendix 2A; EPA, White Paper: Implementation of the 2015 Primary Ozone NAAQS: 

Issues Associated with Background Ozone White Paper for Discussion (Dec. 30, 2015) available at 

https://www .epa.gov/sites/production!fi les/20 16-03/documents/whi tepaper-bgo3-final.pdf 4

° Cheadle, L.C., et al., (2017) "Surface Ozone in the Colorado Northern Front Range and the Influence of Oil and 

Gas Development During FRAPPE/DISCOVER AQ in Summer 2014," Elem. Dei. Anth. 5:61. 

doi: I 0.1525/elementa.254, available at https:!/www.elementascience.org/articles/l 0.1525/elementa.254/ . 41 McDuffie, E., et al., (2016) "Influence of Oil and Gas Emissions on Summertime Ozone in the Colorado Northern 

Front Range," J. Geophys. Res. Atmos., 121, available at http://eprints. whiterose.ac.uk/103000/. 42 Texas Commission on Environmental Quality, Ozone Data Exceptional Event Flag Demonstrations available at 

https:!/www.tceq.texas.gov/airquality/airmodldocs/ozone-data-exceptional-event-flag-demonstrations. 

43 Letter from Jared Blumenfeld, EPA Region IX, to Eric Massey, Director, Air Division Arizona Department of 

Environmental Quality (Sep. 6, 2012) available at https://www.epa.gov/sites/production!files/2015-

05/documents/epa_resp_ltr_tsd_0906!2.pdf. 

44 Letter from Shaun L. McGrath, Regional Administrator, EPA Region 8, to Todd Parfitt, Director, Wyoming 

Department of Environmental Quality (May 28, 2014) available at https:!/www.epa.gov/siteslproduction!files/2015-

05/documents/june_l4 _20 12_strat_o3 _concurrence_letter_28_march_20 14. pdf. 

12 
104 

collaboration forged in law, we will continue to chart a commonsense path forward in protecting 

the health of our children and communities, securing a stronger and more prosperous nation. 

l3 
105 

APPENDIX: Air Quality Exceedances by Region as of June 13, 2018 

REGION 1: 

2: 

REGION 

5: 

REGION 7: 

REGION 

0 

Data retreived from: 

US EPA, available at 

Accessed June 13, 2018 

EPA notes: "The data for the 

current year is from AirNow and is 

presented with baseline data fi·om 

AQS for comparison only. The 

AirNow data are not fully verified 

and validated through the 

assurance procedures 

organizations use to officially 

submit and certify data on the EPA 

AQS (Air Quality System) and. 

therefore, cannot be used to 

fonnulate or support regulation. 

guidance or any other Agency 

decision or position." 

*There was very little complete data for Region 10 therefore it is dillicult to say what the true number is. 

14 
106 

Biography 

Dr. Elena Craft is a Senior Health Scientist at Environmental Defense Fund. For a 

decade, she has strategized to identify, monitor, and mitigate risk from environmental 

pollution from the industrial sector as well as from within the transportation sector, most 

specifically around port areas and freight corridors. In addition, she has facilitated 

development of initiatives to support public health research, including helping to 

establish the Hurricane Harvey Environmental Health and Housing Registry in Houston, 

the first registry established after a major flood event. Dr. Craft's other scientific 

research focuses on understanding health disparities associated with living in pollution 

hotspots. She holds a B.S. degree in biology from UNC Chapel Hill, a M.S. degree in 

toxicology from NC State University, and a Ph.D. from Duke University. She also holds 

an adjunct assistant professorship at the University of Texas Health Sciences Center 

and is a Kinder Fellow at Rice University. 

15 
107 

Mr. NORMAN. Thank you, Dr. Craft. 

I now recognize Mr. Stella for his testimony. 

TESTIMONY OF MR. GREGORY STELLA, 

SENIOR SCIENTIST, 

ALPINE GEOPHYSICS 

Mr. STELLA. Mr. Chairman and Members of the Committee, my 

name is Gregory Stella, and I thank you for giving me the opportunity to testify today on behalf of my firm, Alpine Geophysics regarding information on background ozone concentrations and its 

role in regulatory modeling. 

I especially would like to thank Representative Biggs for the invitation to appear before you. 

As air quality scientists, one of our main objectives is to reduce 

and understand the uncertainty involved with modeling ozone concentrations in past, present, and future timelines. Each data input, 

calculation, model, or method that supports our analyses have their 

own uncertainties that need to be studies in order to understand 

the impact of these elements on policy decisions. 

To this end, there are a number of categories of pollutant concentrations that have inherent uncertainty in a regulatory sense. 

One of those categories is background ozone. 

Background ozone has historically been defined as amounts of 

pollutant concentrations that are produced by sources other than 

people. Because amounts of ozone measured at ambient air quality 

monitors cannot be separated into background or anthropogenic origin, this amount needs to be determined using photochemical modeling and source apportionment tools. 

We know that many sources of background ozone are global in 

origin, and the fact that ozone is not emitted directly; rather, it is 

formed by reaction of hydrocarbon and nitrogen species in the presence of sunlight, complicates the linkage of particular emissions to 

downwind ozone concentrations. 

In the air quality community, we use global chemistry models to 

derive boundary conditions, which include background emissions, 

to inform our regional models. What this means is that we generate global concentrations of ozone at very coarse scale and mesh 

them with our own regional and local modeling platforms, which 

are of a much finer granularity. 

To this, we add regional background ozone concentrations from 

models that estimate biogenic or wildfire emissions, and complete 

the platform with our national inventories of anthropogenic 

sources. 

When we look at all these factors and run our own source apportionment tools with the resulting modeling platforms, we, EPA, and 

others have found that background ozone can range from ten percent of the modeled contribution to close to 90 percent on any single model day, with higher background contributions seen in the 

western high elevation monitor locations. This is a large fraction of 

the current 70 ppbos on NAAQS and can make it very difficult, if 

not impossible, for many regions of the country to attain the 

NAAQS. 

So when that leap is made from science to policy, the various 

definitions of uncontrollable ozone sources become important to 
108 

consider. For example, baseline ozone, U.S. background, global 

background, global anthropogenic background, or even international exceptional vents have all been cited as applicable to 179B 

petitions and potential regulatory relief under the ‘‘but for’’ clause 

of this section of the Act. 

However, to be clear, relief using 179B or exceptional event exclusion does not give anyone cleaner air to breathe. It is simply recognizing a regulatory reprieve based on the language of the law. 

In the air quality community, these options are not seen as a free 

pass to pollute. Rather, this is seen as a reality that must enter 

into the regulatory discussion and be understood in order to develop control programs that maximize air quality benefit with minimal societal disruption. 

Unfortunately, there is a vague regulatory clarity on exactly 

what could be considered in many cases, and therefore, we continue 

to pursue direction in both definition and application as it relates 

to transport contribution of uncontrollable and background ozone 

concentration at local sources. 

From a scientific perspective, improvements to understanding 

background ozone are being developed using collateral model attribution studies among EPA, NOAA, NASA, states, and international 

organizations looking to reduce the uncertainty involved with 

boundary conditions and the relative international contribution to 

domestic air quality problems. Research programs like these are 

vital and are drastically underfunded. Without substantive direct 

funding of these projects, much of the work is being performed as 

an aside to other projects, unacceptable for such an important issue 

on that critical interface of science and public policy. 

In summary, it is absolutely clear that there is an ever-increasing impact of uncontrollable emission sources on the ability of our 

States to achieve attainment with the current air quality standards. While much work has occurred related to the understanding 

of background ozone, and international transport’s contribution to 

locally observed air quality concentrations, we still have a long way 

to go in understanding the contribution of these sources and improving the models and methods used to quantify and qualify their 

use in a regulatory framework. 

I thank you for your time and this opportunity to present this 

information before the Committee, and I will be happy to answer 

any questions that Members have on this topic. 

[The prepared statement of Mr. Stella follows:] 
109 

Written Testimony 

Gregory Stella 

Alpine Geophysics, LLC 

U.S. House of Representatives Committee on Science, Space, and Technology 

June 21, 2018 

Mr. Chairman and Members oft he Committee, thank you for giving me the opportunity to testify today 

regarding information related to the estimation and usage of background ozone concentrations in regulatory 

modeling. I especially would like to thank Representative Biggs for the invitation to appear before you. 

INTRODUCTION 

As air quality scientists, one of our main objectives is to reduce and understand the uncertainty involved with 

modeling ozone concentrations in past, current, or future timelines. Each data input, calculation, model, or 

method that supports our analyses have their own uncertainties that need to be studied in order to understand 

the impact of these elements on policy decisions. 

To this end, there are a number of categories of pollutant concentrations that have inherent uncertainty in a 

regulatory sense. One of those categories is background ozone. 

Background ozone has historically been defined as amounts of pollutant concentrations that are produced by 

sources other than people. Because amounts of ozone measured at ambient air quality monitors cannot be 

separated into background or anthropogenic origin, this amount needs to be determined using photochemical 

modeling and source apportionment tools. We know that many sources of background ozone are global in 

origin, and the fact that ozone is not emitted directly, rather, it is formed by reaction of hydrocarbon and 

nitrogen species in the presence of sunlight complicates the linkage of particular emissions to downwind ozone 

concentrations. 

As is shown in Figure 1, the last decade has seen significant improvement in ozone air quality over most of the 

U.S., based on the 4'" highest observed regulatory value (design value); however some parts of the country have 

seen flatter trends or even elevated levels of ozone largely thought to be the increased contribution of 

background ozone (Figure 2). 
110 

Figure 1. Trends in 2007 to 2016 MDA8 3-year ozone design values (parts per billion by volume; ppb) at AQS 

sites with a complete data record. Data Source: https:(/www.epa.gov/air-trends/air-quality-design-values 

Figure 2. Trends in summer daytime average ozone, 2000 to 2014, 4th high maximum daily 8-hour ozone across 

all sites. Source: Tropospheric Ozone Assessment Report (Schultz et aL, 2017) 
111 

BACKGROUND OZONE MODELS 

As an air quality community, we use global chemistry models like Goddard Earth Observing System- Chemistry 

model (GEOS-CHEM), Model for OZone And Related chemical Tracers (MOZART), or Geophysical Fluid Dynamics 

Laboratory- Atmospheric Component 3 (GFDL-AM3) to derive boundary conditions, which include background 

emissions, to inform our regional models. What this means is that we generate global concentrations of ozone 

at very coarse scale and mesh them with our own regional and local modeling platforms which are of a much 

finer granularity. 

These estimates are informed by global emission inventories of varying quality depending on the state-ofscience in each source county. Here in the U.S., we support the global models with our EPA-generated National 

Emission Inventories (NEI), arguably of the highest quality in the world that uses continuous emission monitors, 

regular stack testing, and model generated quantification oftentimes corroborated with on-ground 

measurements. For other counties without regulatory agencies or support in inventorying its emitting sources, 

these data may be developed in a top-down manner using methods like population-based emission factors. To 

this we add regional background concentrations from models that estimate biogenic or wildfire emissions and 

complete the platform with our national inventories of anthropogenic sources. 

One of the greatest challenges we face in using these global models is the scaling of the coarse information to 

match the configuration of our regional models. Each model may have a different temporal, spatial, or chemical 

composition compared to the regional configurations and yet provide information of great importance to our 

regional and local-scale policy-informing science. 

For the background categories that are generated within the U.S. boundaries, we also use models to derive 

biogenic emissions or NOx from soil, either natural or fertilized. Models like the Biogenic Emission Inventory 

System (BE IS) or Model of Emissions of Gases and Aerosols from Nature (MEGAN) estimate the emission of 

gases and aerosols from terrestrial ecosystems into the atmosphere. Driving variables include landcover, 

weather, and atmospheric chemical composition. However, even with the higher quality data available to us to 

support these models, different versions of our biogenic models can have widely ranging results for speciated 

components of ozone precursor emissions leading to increased uncertainty in our background calculations. 

Wildfire emissions can be based on models, like the SMARTFIRE2 system, to estimate wild land fire emission 

estimates augmented with local activity data (acres burned, types of fuels, fuel consumption values, etc.) 

obtained from ground-level surveys to make emission estimates for both wild and prescribed fires more 

accurate. Other options include the Fire INventory from the National Center for Atmospheric Research (NCAR) 

(FINN) that uses satellite observations of active fires and land cover, together with emission factors and 

estimated fuel loadings to provide daily, highly-resolved (1 km) open burning emissions estimates for use in 

regional and global chemical transport models. 

CONTRIBUTION OF BACKGROUND TO MODELED OZONE CONCENTRATIONS 

When we look at all these factors and run our source apportionment tools on the resulting modeling platforms, 

we, EPA, and others have found that background ozone can range from 10 percent of the modeled contribution 

to close to 90 percent on any single modeled day. Over an entire year, this can average to greater than 50 ppb 

3 
112 

of total modeled ozone depending on location; with higher background contribution seen in the western, high 

elevation monitor locations. This is a large fraction of the current 70 ppb ozone standard and can make it very 

difficult, if not impossible, for many regions of the country to attain the NAAQS. Figure 3 represents the source 

apportioned contribution of U.S. anthropogenic emissions compared to the regulatory design value (4'h highest 

observed day) for a 2011 modeling episode. In this example from EPA, as much as 85 percent of modeled ozone 

in the western Rockies region comes from categories other than U.S. anthropogenic sources with a minimum of 

no less than 18 percent contribution across the rest of the country. 

----~----------~------------------~~--------------, 

Figure 3. Map of estimated anthopogenic U.S. contribution to ozone design values based on CAMx source 

apportionment modeling (2011). Larger circles represent sites with 2015 DV2 > 70 ppb. Source: Dolwick, P. MidAtlantic States Section Annual Workshop, "Ozone: Challenges, Trends, Strategies, and New Developments." New 

Brunswick, NJ, October 12th, 2017. 

An overall impact assessment of the influence of background ozone with respect to boundary condition 

modeling is extremely important as the level of the ozone NAAQS decreases and the relative contribution of 

boundary condition emissions increases. In many parts of the country, the contribution of controllable U.S. 

sources is a small portion of the overall ozone concentration which includes both background and local 

contribution. As the incremental cost of every ton of emissions increases, a diminishing rate of return on U.S. 

control programs impacting air quality, nationally, regionally, or locally is being observed with historically 

comparable levels of emission reductions. 

REGULATORY IMPACT OF BACKGROUND OZONE 

The importance of transported pollution has long been understood. The Clean Air Act has provisions to account 

for it. Section 1796 of the Clean Air Act states, with respect to ozone, that "any State that establishes to the 

satisfaction of the Administrator that, with respect to an ozone nonattainment area in such State, such State 

4 
113 

would have attained the national ambient air quality standard for ozone by the applicable attainment date, but 

for emissions emanating from outside of the United States". 

In the 2008 ozone SIP Requirements Rule, the EPA stated that a Section 1798 demonstration could include 

consideration of any emissions from North American or intercontinental sources. (80 FR 12293). The EPA also 

stated at that time that it did not believe use of section 179B was limited to nonattainment areas adjoining 

international borders. 

More recently, however, in the Proposed Implementation of the 2015 National Ambient Air Quality Standards for 

Ozone: Nonattainment Area Classifications and State Implementation Plan Requirements (81 FR 81276), EPA 

requested comment on narrowing the scope of the Section to just international border states based on its 

anticipation that section 179B will most often be used by states with areas along the border with Mexico and 

Canada and the Agency's historic use of its CAA section 179B authority to approve attainment plans in the 

immediate vicinity of the Mexican border, including El Paso, Texas, Imperial Valley, California, and Nogales, 

Arizona. 

So when that leap is made from science to policy, the various definitions of uncontrollable ozone sources 

become important to consider. For example, baseline ozone, or U.S. background, or global background, or global 

anthropogenic background, or international exceptional events have all been cited as applicable to 179B 

petitions and potential regulatory relief under the "but for" clause of this section of the Act. 

This is also similar to what is seen in the application of the exceptional events rule (Section 319 oft he Clean Air 

Act), another regulatory definition, that allows a state to request elimination of a high concentration day from 

its design value calculation when influence is.proven from contribution from a non-recurring, uncontrollable 

event like a wildfire, dust storm, stratospheric intrusion, or other internationally influenced event. EPA has 

recently made the process easier for states to make an exceptional event exclusion request in addition to other 

improvements underway at the Agency and elsewhere to address these issues. 

However, to be clear, relief using 179B or exceptional event exclusion does not give anyone cleaner air to 

breathe. It simply recognizes a regulatory reprieve based on the language of the law. In the air quality 

community these options are not be seen as a "free pass" to pollute. Rather this is seen as a reality that must 

enter into the regulatory discussion and be understood in order to develop control programs that maximize air 

quality benefit with minimal societal disruption. Unfortunately, there is vague regulatory clarity on exactly what 

could be considered in many of these cases and therefore we continue to pursue direction in both definition and 

application as it relates to transport contribution of uncontrollable and background ozone concentrations at 

local locations. 

CURRENT WORK UNDERWAY 

The current state-of-science related to global background ozone modeling indicates that these models can 

provide key inputs to regional modeling activities. However, at this time, what is important to the global 

modeling community is not what is important to the regional modeling community. It is up to us to use the data 

responsibly which means we first need to understand the inputs. Like our own national inventory, global 

emissions are not constant and therefore background contributions also vary from year to year. Understanding 

5 
114 

these changes to adequately include and project future years' background concentrations is extremely 

important if we are to define effective national, regional, or local control programs. 

Nationally, we also need to understand how changing climate is related to increasing wildfire activity and 

international emissions; how changes in land use and drought conditions can impact biogenic background 

emissions; and how our own control programs can be limited by the increases in uncontrollable source 

contribution. 

From a scientific perspective, improvements to understanding background ozone are being developed using 

collaborative model attribution studies among EPA, NOAA, NASA, states, and international organizations looking 

to reduce the uncertainty involved ll{ith boundary contribution and associated relative international 

contribution to domestic air quality problems. Several of these are long-term programs, like the Task Force on 

Hemispheric Transport of Air Pollution (HTAP) organized under the UNECE Convention on Long-range 

Transboundary Air Pollution (LRTAP) has been looking at improving the assessment of the quantification, 

temporal and spatial distribution, halogen chemistry at the global scale, vertical transport between the free 

troposphere and the boundary layer, international contribution, evaluation of concentrations aloft in elevated 

layers, and consistency in the coupling of global models to regional models. Research programs like these are 

critical and are drastically underfunded. Without substantive, direct funding of these projects, much of the work 

is being performed "on the side" of other projects; unacceptable for such an important issue on that critical 

interface of science and public policy. 

Additional support for these programs will allow us to better understand the uncertainty involved in this area 

and provide the technical information necessary for states to develop plans for attaining national ambient air 

quality standards. 

SUMMARY 

In summary, it is absolutely clear that there is an ever increasing impact of uncontrollable emission sources on 

the ability of our states to achieve attainment with the current air quality standards. While much work has 

occurred related to the understanding of background ozone and international transport's contribution to locally 

observed air quality concentrations, we still have a long way to go in understanding the contribution of these 

sources and improving the models and methods used to quantify and qualify their use in a regulatory 

framework. 

I thank you for your time and this opportunity to present this information before the Committee, and I am 

happy to answer any questions that Members may have on this topic. 

6 
115 

Gregory Stella 

Senior Scientist and Managing Partner 

Alpine Geophysics, LLC 

Mr. Stella is internationally recognized as a technical authority in the modeling and policy application of 

emission inventories for ozone and particulate matter pollutants and precursors. For over twenty-five 

years he has coordinated with both public and private workgroups, modeling centers, and stakeholders 

to develop, evaluate, and apply control measures and program designs in support of emissions and air 

quality policy decisions. 

Prior to joining Alpine Geophysics in 2003, Mr. Stella was at on staff at EPA's Office of Air Quality 

Planning and Standards where he managed and prepared the emission inventories, control strategies, 

and associated temporal, spatial and speciation data for the Regional Transport NOx SIP Call, Section 

126 rulemaking, Tier-2 tailpipe standards, 1-hour attainment demonstrations, Heavy-Duty Diesel Engine 

standards, Multi-Pollutant legislation, Clear Skies Analysis, and US/Canadian Air Quality Agreements. Mr. 

Stella is a recipient oftwo U.S. EPA Gold Medals for the NOx SIP Call Rulemaking (1999) and the Tier-2 

Tailpipe Standard (2001); projects in which he participated while at EPA. 

Mr. Stella received his Bachelors of Science degree in Chemical Engineering from the Johns Hopkins 

University in Baltimore, Maryland. 
116 

Mr. NORMAN. Thank you, Mr. Stella. I want to thank all the witnesses for testifying. 

The Chair now recognizes himself for five minutes of questioning. 

This is up close and personal for me, this topic. I’m a real estate 

developer, and to have companies to come into an area and to be 

on the verge of breaking ground, and then to be put into nonattainment status is tragic. And Ms. Rath, your chart showing 20 percent—80 percent basically comes from outside with no control is 

real. 

So I direct my first question to Mr. Franquist. Can you explain 

the remedy a State can get from a successful 179B demonstration 

for international ozone? 

Mr. FRANQUIST. Mr. Chairman and Members of the Committee, 

I can. That’s what’s referred to as the 179B International Transport Demonstration. The relief really looks like this. What it does 

is what’s commonly referred to as a ‘‘but for’’ analysis is that under 

the Clean Air Act, if you don’t meet a standard within the given 

time, you’re automatically bumped up to the next higher classification of nonattainment. Under the 179B, if you can make that demonstration successfully, that will simply stop that bump up to the 

higher nonattainment area classification. 

The challenge there is you’re still in that nonattainment classification, until which time—in this case for us in Arizona, we’re 

waiting for international emissions to drop. So the relief looks a lot 

like perpetual nonattainment. It looks a lot like nonattainment 

NSR for potentially decades, if we’re waiting on international emissions to decrease. 

Mr. NORMAN. Do you believe that this is a sufficient remedy compared to the amount of ozone that comes from international sources 

that affects the attainment? 

Mr. FRANQUIST. Mr. Chairman and Members of the Committee, 

I do not. Again, in my testimony I want to make it very clear that 

we’re not disputing some of the health challenges of ozone, but 

what often gets lost in this conversation is the health effects of poverty. And so when we look at areas like Yuma, Arizona, 19 percent 

unemployment, 19 percent of the residents there live below the 

poverty line, healthy economies matter. 

And so when we’re looking at public health holistically, we do 

need to look at how these remedies, or lack thereof, actually really, 

truly do protect the residents of those nonattainment areas. 

Mr. NORMAN. You’re from Arizona. How do the strict ozone regulations drive business away from rural counties? 

Mr. FRANQUIST. Mr. Chairman and Members of the Committee, 

it becomes a discouraging factor. It’s a very simple analysis. If 

you’re going to have to do emission offsets, they range in Arizona 

anywhere from $5 to $10,000 per ton, or you can look to an area 

that isn’t an attainment area. It’s a very easy economic choice. 

You’re going to go to the area that does not have the nonattainment area issues. So it discourages large businesses. 

I would say the other challenge with what we call the traditional 

offset piece is that normally if a business was looking to get those 

offsets, what they would do is either shut down a business and capture that headroom with those emissions, or put on a pollution control device on an old business and capture those emissions. What 
117 

that does is simply shuts down a business. That may not be a net 

gain in jobs, so that business even may be able to come into that 

nonattainment area, but from a job perspective, it may be a net 

zero or even a loss of jobs, depending on what facility they decide 

to shut down to get those offsets. 

Mr. NORMAN. So why can’t the businesses in rural counties offset 

ozone emissions like the businesses do in the cities? 

Mr. FRANQUIST. Mr. Chairman and Members of the Committee, 

typically under the traditional offset programs, what you’re looking 

to do is what I just explained, either shut down a business or put 

pollution controls on an existing business. When you’re in a rural 

area, those businesses, those large companies—or even small companies—to get those offsets, are scarce to nonexistent. So when you 

look in the Yuma area, we simply just don’t have the large heavy 

industry there to even generate offsets. So we have to look to 

what’s considered non-traditional offsets, things like captured 

fleets, electrification of truck stops, but it’s extremely difficult to 

generate those non-traditional offsets and also get a rule through 

with the EPA, because it’s very difficult to prove how you qualify 

and enforce some of those offsets. So for the most part, states and 

local areas do not chase down the non-traditional offset programs. 

Mr. NORMAN. Okay. Mr. Stella, what type of parameters go into 

the models that examine background ozone, and do you consider 

them reliable? 

Mr. STELLA. Thank you for the question, Mr. Chairman. 

There are a number of parameters related to both emissions inputs or meteorology, or even the chemistry of ozone formation that 

go into our local scale models, and these are largely informed by 

the global community. The inventories that we have here in the 

United States are of a higher quality than those that go into the 

global model, and so when we try to mesh the two, we need to best 

understand exactly what we’re putting into our simulations. 

Right now, it’s the what goes in comes out sort of paradigm of 

the modeling, and until we can improve and understand what 

those conditions are, we’re going to be at a loss at fully quantifying 

and qualifying how much international or boundary condition impact we have on our local scale monitors. 

Mr. NORMAN. Thank you. The Chair now recognizes Ms. 

Bonamici for five minutes for questioning. 

Ms. BONAMICI. Thank you, Mr. Chairman, and before I ask my 

questions, I want to point out that Dr. Craft included in her submitted written testimony excerpts from the American Lung Association’s State of the Air 2018 study, and she notes that in her 

home State of Texas, there were over 400 orange, red or purple 

high ozone days. Fourteen counties received a grade of F in Texas 

for ozone pollutions. I know there are a lot of Texas members on 

this Committee and I wanted to point that out. 

Dr. Craft, environmental challenges are often disproportionately 

felt by some of our most vulnerable populations. That includes children and the elderly, but also the economically disadvantaged of all 

ages. Some opponents of Federal ozone standards attempt to use 

this as a justification for not acting on air pollution by claiming 

that the cost of implementation will fall on impoverished commu-
118 

nities, then suggesting that it would be better for these communities to suffer the effects of the pollution than to bear the costs. 

Also, I noted Chairman Smith in his opening statement said that 

the NAAQS standards we’re discussing today create burdens without clear benefits, so Dr. Craft, can you respond to the idea that 

these populations would be better off without regulations? What 

are the public health costs of not implementing the current standard? 

Dr. CRAFT. Yes, I’d be happy to share some information about 

healthcare cost numbers. 

Two of the largest respiratory disease challenges that we have in 

this country are COPD and asthma. COPD is actually the third 

most common cause of death in the United States. In 2014, medical 

costs for COPD in the U.S. was $36 billion and projected to be $50 

billion by 2020. Seventy-six percent of those medical costs were primarily paid for by Medicare and Medicaid. 

For asthma, peer reviewed research from this year indicates asthma costs the U.S. economy more than $80 billion annually and 

medical expenses, missed work days, and school days, as well as 

premature death. 

Ms. BONAMICI. Thank you, and Dr. Craft, in your testimony you 

mentioned that anthropogenic sources, rather than background 

ozone, are the main driver of unhealthy ozone levels. And you also 

talk about how emissions reduction strategies do exist, but as you 

mentioned, they are often not implemented. 

We have great potential in this country for innovation. So can 

you talk about the over-emphasis of background ozone and the 

downplaying of anthropogenic sources of air pollution by opponents 

of strict ozone standards, why are known emissions reductions 

technologies not being implemented, and what can the EPA do to 

encourage or enforce the use of these emissions reduction strategies? 

Dr. CRAFT. Right. So there are a couple of things there. 

One thing that I wanted to highlight is the way that the design 

values are calculated in this country to determine attainment or 

nonattainment is that areas look at the fourth highest average over 

the past three years. So it’s not that an area has come into attainment or out of attainment based on some annual percentage of 

ozone. 

So the question of background really needs to look at is background contributing to exceedance of the design value, not an exceedance of the 8-hour daily. So I just wanted to clarify that a little 

bit. 

Could you repeat the last question that you mentioned? 

Ms. BONAMICI. Yes, about the technologies. Is there some reason 

why—I mean, you suggested that there are technologies that exist, 

but they’re not implemented. What are the technologies that are 

not being implemented and what can the EPA do to encourage or 

enforce the use of these emissions reduction strategies? 

We’ve had conversations on this Committee before about regulation and policy driving innovation and technology changes, so can 

you talk a little bit about that? 

Dr. CRAFT. Yes, and since we are talking a lot about the intermountain West, I wanted to mention a lot of controls that have 
119 

been developed over the last couple of years regarding pollution 

controls for oil and gas development. Peer-reviewed publication 

from the Cooperative Institute for Research and Environmental 

Sciences examined the oil and gas sector’s contribution to ozone formation on Colorado’s front range, specifically focusing on days that 

exceeded the ozone NAAQS. The study found that on individual 

days, ozone and gas ozone precursors can contribute in excess of 30 

part per billion to ozone concentrations and could be the primary 

driver of exceedance of the ozone NAAQS. 

There are new pollution controls that have been implemented. 

Administrator Pruitt has issued a stay on those controls, and so 

right now we’re not getting the benefit of those pollution controls 

in limiting excess emission—controls that would save the oil and 

gas sector money. 

Ms. BONAMICI. Was there a reason stated for that—implementing 

that stay? 

Dr. CRAFT. Not that I know of. 

Ms. BONAMICI. I see my time is expired. I yield back. Thank you, 

Mr. Chairman. 

Mr. NORMAN. Thank you. The Chair now recognizes Chairman 

Smith for his questions. 

Chairman SMITH. All right. Thank you, Mr. Chairman. 

Mr. Chairman, first of all I’d like to point out that Ms. Bonamici 

in her mentioning of the 14 counties in Texas that were not in attainment omitted the fact that there are 254 counties in Texas. 

Fourteen out of 254 ain’t bad, particularly when in many of those 

counties, if not all of them, much of the ozone is international 

ozone from Mexico. My guess is that if Oregon were subjected to 

75 percent of the ozone in that State coming from Canada, she 

might have a different view of the attainment restrictions and the 

application of NAAQS. 

But I’d like to address my first question to Ms. Rath, and that 

is what has San Antonio done to remain in attainment with the 

2008 ozone NAAQS? 

Ms. RATH. Thank you very much, Mr. Chairman. I really have 

to salute both our public and our private entities for what they 

have implemented voluntarily out of concern for the health to ensure they are in compliance. We have had very aggressive action 

taken. 

CPS Energy, which is our municipally owned electrical utility 

company, has been very, very aggressive to reduce the demand for 

electricity from coal-fired power plants. They implemented programs and the savings were equal to shutting down a mediumsized coal plant. They met their goal of producing 1,500 megawatts 

of renewable energy capacity two years ahead of schedule, and this 

is equal to 20 percent of their power generation. And that portfolio 

includes both wind, rooftop solar, and utility scale solar. 

I have to really thank CPS Energy for two aggressive actions 

they will be doing this year that will have a significant impact 

upon our ozone precursors. 

Chairman SMITH. Okay. 

Ms. RATH. They are shutting down the Deeley plant, which is our 

largest and oldest coal-powered plant, shutting that down early 

which will have a significant improvement, and they’ve made tre-
120 

mendous investment of the technology at our remaining Spruce 

plant for that. 

In addition—— 

Chairman SMITH. Okay. Let me go briefly to my next question, 

which is what are some of the economic consequences of a nonattainment designation? 

Ms. RATH. Yes, sir. Last year, we contracted with economists at 

St. Mary’s University to look at the cost of nonattainment in Bexar 

County, and at a marginal classification, the low estimate is over 

$117 million annually. The high estimate is over $1 billion annually. So for every year we’re in nonattainment, there’s a potential 

for over $1 billion cost to just our eight county MSA. 

Chairman SMITH. Okay, and that has an impact on economic 

growth and jobs and income and everything else. Okay. 

Ms. RATH. Very much so, yes, sir. 

Chairman SMITH. Let me ask a final question to all of our panelists here today, and that is should international ozone be taken 

into consideration when applying NAAQS to various regions in the 

U.S.? Okay, Ms. Rath? 

Ms. RATH. I certainly think it should. How can you hold a community or a region responsible for what’s totally and completely 

outside of its control? If they would take international transport in 

consideration, we would be well under the limit because we’re barely exceeding it, 72 and 73 parts per billion at our two regulatory 

monitors. 

Chairman SMITH. Okay, thank you, and Mr. Franquist? 

Mr. FRANQUIST. I would agree with Ms. Rath. I think we have 

to take it into consideration, especially when we’re seeing studies 

indicate that 83 percent of the ozone in Southern Arizona is from 

international sources. 

Chairman SMITH. Okay, thank you. Dr. Craft? 

Dr. CRAFT. I would actually disagree with Ms. Rath. I would 

point to the 2015—— 

Chairman SMITH. Let me make certain I understand you. You do 

not think international ozone should be taken into consideration? 

Dr. CRAFT. I guess what I’m saying is that if—are you talking 

about San Antonio specifically? 

Chairman SMITH. No. No, just in general should international 

ozone be taken into consideration when we apply NAAQS to various regions in the U.S., wherever it might be? In other words, obviously San Antonio is an example. If you’ve got 75 percent of the 

ozone being international ozone, should that be taken into consideration? 

Dr. CRAFT. Well there’s two things. One is that international 

transport is actually a very small percentage of the ozone in the 

region. 

I wanted to point out one inaccuracy in Mr. Franquist’s opening 

statement—— 

Chairman SMITH. I’ll tell you what, before you go to the other 

witnesses, I’d just like an answer to my question. And really, it’s 

yes or no. Should the international ozone be taken into consideration when applying NAAQS? 

Dr. CRAFT. It is taken into consideration. 

Chairman SMITH. Okay. So you’re saying it should be? 
121 

Dr. CRAFT. It is already, yes. 

Chairman SMITH. Okay. Well saying it is doesn’t answer the 

question as to whether you feel it should be. 

Dr. CRAFT. Saying it is is saying that it is already being taken 

into consideration. 

Chairman SMITH. And you agree with that? 

Dr. CRAFT. All sources of ozone are taken into consideration in 

regard to the NAAQS. 

Chairman SMITH. But you agree that international ozone should 

be taken in consideration? I assume you’re saying yes. 

Dr. CRAFT. Yes, it already is. 

Chairman SMITH. Okay, thank you. Mr. Stella? 

Mr. STELLA. From a designation perspective, I would have to say 

that I would agree that it is and I don’t necessarily think that you 

can quantify that amount as you go into the designation. But from 

an attainment demonstration perspective, I do believe that international emissions need to be accounted for. But we have to be cautious because of the large uncertainty in predicting that amount. 

Chairman SMITH. Fair enough. 

Thank you, and thank you, Mr. Chairman. 

Chairman BIGGS. Thank you. The Chair recognizes the 

gentlelady from Texas, Ms. Johnson. 

Ms. JOHNSON. Thank you very much, Mr. Chairman. 

I have some concerns myself about the consideration of international. Does it—when you have the ozone pollution, no matter 

what the source it still has an effect on health, right? 

Dr. CRAFT. That’s correct. 

Ms. JOHNSON. So are you aware of any efforts that have been 

made to mediate some of that where you have an international influence? 

Dr. CRAFT. Yes, EPA has actually addressed that very issue a 

couple of times. What I was trying to reference a bit earlier was 

the technical support document which was released. It’s entitled 

‘‘Intended Area Designations for the 2015 Ozone National Ambient 

Air Quality Standards Technical Support Document’’ that references some of the work in San Antonio. On page 21 of that technical support document, it says ‘‘From the same modeling results, 

a more reasonable estimate of the impacts from manmade emissions from Mexico is on the order of less than 1 part per billion,’’ 

so 1 to two percent of the ozone projected for 2023 in San Antonio. 

That’s one piece. 

I wanted to also clarify one of the references made by Mr. 

Franquist. He mentioned 65 percent of ozone increase in the Southwest is coming from Asia. The paper that he’s referencing is actually a Lin paper, and the reference is 65 percent of the increase in 

background, not total ozone. So that’s actually less than a part per 

billion. I’d like to just make sure that that’s accurate for the record. 

Ms. JOHNSON. Now Dr. Craft, in your testimony you discuss 

EPA’s delay in determining whether San Antonio meets the 70 

parts per billion standard set in 2015. This delay is despite the fact 

that monitors have detected exceedances for years. What is causing 

that delay? Are you aware? 

Dr. CRAFT. As far as I am aware, EPA is the cause of that delay. 

It was only in response to a lawsuit filed by States and public 
122 

health and environmental organizations that EPA has even taken 

initial steps to identify certain areas of the country that do not 

meet the 2015 standard. This comes almost an entire year after the 

designations were due, meaning that communities with unhealthy 

levels of ozone will face another summer without solutions in place 

to clean up the air. 

I wanted to highlight an additional issue that’s going on in San 

Antonio. It is correct that ground—that folks on the ground in San 

Antonio have stepped up to support clean air policies. Unfortunately, the Governor of Texas vetoed clean air planning dollars for 

the region of San Antonio. Over a million dollars’ worth of planning 

dollars are gone as part of a line item veto by Governor Abbott. He 

claimed that he wanted planning dollars to go to nonattainment 

areas. San Antonio, for all intents and purposes, is actually not in 

attainment. It’s not officially designated, but it has exceeded the 70 

part per billion standard for several years now. 

Ms. JOHNSON. Well I’m from Dallas, and we don’t have San Antonio that close around, but we are seeing more and more children 

and seniors getting asthma. 

Have you seen any effect of that in your research in San Antonio, 

and what—does that make the cost and the costs on health important or not? 

Dr. CRAFT. Of course, yes. I also wanted to highlight to that 

point very recent evidence from studies published within the last 

year solidifying the link between ozone exposure and an increased 

risk for death. The key study lead author Domenici assessed impacts in 61 million Medicare beneficiaries over 13 years in the 

United States and found that the risk of death associated with 

ozone exposure continued below the current NAAQS. That—those 

61 million people are Americans who are experiencing health effects at concentrations below the current standard. 

Ms. JOHNSON. Thank you very much. My time is expired. 

Chairman BIGGS. The gentlelady’s time is expired. The Chair 

now recognizes the gentlelady from Arizona, Representative Lesko. 

Mrs. LESKO. Thank you, Mr. Chair. And I want to thank the entire panel for coming here and educating us on this issue. I specifically want to say thank you to Mr. Franquist, who came from Arizona. And while I was in the State Senate, I always had good dealings with your agency, and I think they do a good job. 

I think it’s really important—I think everybody cares about air 

quality. I don’t think there’s a question about that. I mean, my 

daughter had asthma. My grandchildren sometimes need to use an 

inhaler as well. But I really think we need to balance that with 

reasonable measures that we have influence over. So what I heard 

here today is a lot of it has to do—or at least a large part of it 

along the border has to do with pollution that comes over from 

other countries. 

I do have a question for Mr. Franquist. Mr. Franquist, what 

changes would you propose to the current National Ambient Air 

Quality Standards process to improve the way that it’s implemented in the States? 

Mr. FRANQUIST. Mr. Chairman, Members of the Committee, I 

think, first of all, I would start to take a look at the five-year review cycle. Every five years the EPA has the opportunity to take 
123 

a look at the NAAQS. It seems to be pretty consistent that the 

NAAQS goes up every single year, and that’s challenging for areas 

that have to put in state implementation plans. You have three 

years to do that. It seems by the time we implement just the beginning states of state implementation plans, we’re right back chasing 

the tiger’s tail again and having to come up with new measures. 

So I think, you know, that’s one place I would certainly start. 

Again, one area that, you know, we’ve been working closely with 

Senator Flake on is removing some of the nonattainment new 

source review offsets and lowest achievable mission requirements 

for those international transport areas. It seems to me if you could 

make a strong demonstration that those areas are not exceeding 

the standard but for emissions outside this country—and I’ll go 

back and sharpen my pencil and make sure that the Lin study— 

the 65 percent increase. What I do know is the U.S. EPA’s modeling said 83 percent of emissions in southern Arizona are from 

outside of this country, and so we do need to take a strong look at 

how those areas with 19 percent living below the poverty line can 

find access to good work and therefore good health care. And so, 

again, I think relieving those areas of layer and offset requirements 

would be another good place to start. 

Mrs. LESKO. Thank you. And, Mr. Chairman, I have one more 

question. 

Chairman BIGGS. Please. 

Mrs. LESKO. Thank you. Mr. Franquist, as a follow-up, what has 

the EPA currently done or what could they continue to do to help 

the states? 

Mr. FRANQUIST. Mr. Chairman, Members of the Committee, we’re 

still awaiting the implementation rule for ozone. Under the past 

Administration, there was a proposal that these international 

transport areas would be required to implement reasonable available control measures before the area was reviewed under international transport demonstrations, which simply means that these 

areas that are shown not to be contributing to those issues would 

have to go above and beyond, put control measures in place to control emissions that are coming from somewhere else outside this 

country. So as we look to the EPA to finalize the implementation 

rule, I think, you know, certainly one area would be not requiring 

RACM for international transport areas. 

Mrs. LESKO. Thank you, sir. I yield back my time. 

Chairman BIGGS. The gentlelady yields back. 

The Chair recognizes the gentleman from Pennsylvania, Mr. 

Lamb. 

Mr. LAMB. Good morning. Dr. Craft, I believe you’re aware that 

in 2016 EDF worked with Peoples Gas and Carnegie Mellon University on a methane mapping study, basically that I think was designed to identify areas of methane leaks and figure out how Peoples and their partners could remedy them. Could you talk a little 

bit about that project and how it’s related to ozone reduction? 

Dr. CRAFT. Sure. So EDF partners with science; we partner with 

the private sector. The work that we have done looking into methane issues was done—that particular project was done in partnership with Google. What we did was we outfitted the Google streetview cars with methane sensors, and we drove around cities detect-
124 

ing methane leaks. These were primarily coming from pipelines 

around the city. 

And we drove around a couple of cities in the United States, Boston, Indianapolis, Pittsburgh, as you mentioned, and one of the 

things that we noted was that the older the cities, the older the 

pipeline infrastructure, generally the more leaks that are there. 

That’s important because methane emissions actually contribute to 

ozone formation. Globally, you can see that methane emissions are 

actually on the rise and contributing to estimates between 1 and 

3 part per billion. 

We are very interested in trying to curb those methane emissions 

in part because of the climate impacts. Methane is 84 times more 

potent as a greenhouse gas warmer over 20 years as compared to 

carbon dioxide. We are investing millions of dollars in launching a 

satellite to measure ground-level methane around the world. That’s 

how important we think that issue is. If we can curb methane, we 

can actually prevent some of the ozone that is formed by those releases. 

One additional item that I wanted to mention is that our organization has a peer-reviewed paper that is actually going to be coming out today looking at methane emissions and looking at the 

underestimates that—in terms of emissions inventories that exist. 

Mr. LAMB. I’d really like to take a look at that. If you could send 

us a copy, I’d appreciate it. 

Dr. CRAFT. Sure. 

Mr. LAMB. Are you aware of—what were the gas companies able 

to do after that study took place in order to remedy the situation? 

Dr. CRAFT. So the main thing that they were able to do is to replace those leaky pipes, and what we were able to do through our 

work was to highlight where the leakiest pipes were so that they 

could prioritize. I don’t think anyone expects anyone to go in in a 

week and replace all of the pipes under an entire city, but if you 

know where the biggest leaks are, you can prioritize those, go in 

and address them, and get those reductions. It saves everybody 

money if we’re not leaking natural gas from these pipelines. 

Mr. LAMB. And do you think there’s anything that we can do 

here to encourage similar partnerships or larger-scale projects 

based on the one that you guys did? 

Dr. CRAFT. I mean, one thing is that we need to go back and 

make sure that there are pollution controls from the oil and gas 

sector generally. Those federal rules have been in place to protect 

everyone across the country. It would help tremendously to Intermountain West if we could—there are places in Wyoming that 

never had an ozone exceedance day before some of the oil and gas 

activity ramped up. So if we put those commonsense pollution controls on that save money, then that helps everybody. 

Mr. LAMB. Great. Thank you. Mr. Chairman, I yield back. 

Chairman BIGGS. The gentleman yields back. 

The Chair recognizes the gentleman from California, Mr. Rohrabacher. 

Mr. ROHRABACHER. Thank you very much. I’m trying to catch up. 

Sorry I’m late but it happens here in Washington. You got five different things you got to do and they’re all important. And I think 

this is an important hearing because we need to be educated about 
125 

this quite frankly, and I’m not educated about it, so I appreciate 

you sharing some of your knowledge. 

To the whole committee, what percentage of the atmosphere is 

ozone? What are we talking about here? What percentage of the atmosphere is ozone? We know how much the CO2 is. We kind of 

know what methane is. Ozone isn’t a percentage of the atmosphere? 

Mr. STELLA. That’s an interesting question. I think from a holistic value, I’m not sure that that can be answered adequately. I 

think the measurements that we tend to take are more on a regional and local scale, and so we look at the ambient conditions 

sort of respective of individual areas. 

Mr. ROHRABACHER. So the fact that we may not have a global 

problem here but we have a problem in places? 

Mr. STELLA. Well, I think there is absolutely a global problem, 

and I think what we’re focusing on here today is how that impacts 

us locally. 

Mr. ROHRABACHER. Does anybody else—— 

Dr. CRAFT. Well, I guess I’ll just add. So there are different types 

of ozone. We have ground-level ozone, and that’s the ozone that is 

harmful. That’s why we regulate it across the country. There’s also 

stratospheric ozone, and that actually is protective. It protects us 

from UV radiation coming from the sun. 

Mr. ROHRABACHER. Okay. 

So there’s good ozone and bad ozone? 

Dr. CRAFT. Good ozone and bad ozone. One of the issues in the 

Intermountain West, which is why it’s a challenge, is that in some 

of these high-elevation places, what happens is there are stratospheric intrusions meaning that some of the ozone, the good ozone 

that’s in the stratosphere, can actually intrude into the troposphere 

and contribute to some of the ground-level ozone problem. 

The other issue with high-elevation areas is that the chemistry 

of ozone is a little bit different. It sticks around a little bit longer. 

And that’s where you see sort of some of the pollution issues coming in, blowing in from other States and whatnot. 

Mr. ROHRABACHER. So we—and I know that’s what the subject 

of the hearing is is we want to focus on what’s happening and how 

it impacts on health in terms of the lower level and that really has 

very little to do with the higher level of ozones. 

Dr. CRAFT. Correct. So we’re talking about ground-level ozone 

here. 

Mr. ROHRABACHER. Okay. And you were mentioning how different dealings—and again, I’m an amateur on this. This is not 

something—I’m happy you’re here to tell us about it. There are 

leaks from oil and gas—and I remember in California we had a 

huge problem, a health problem, and then we were requiring 

things on the engines of our cars that cut down ozone. And was 

that something—was the ozone higher before that and then we 

made it lower because of that? And did that impact on health? 

Dr. CRAFT. So ozone is actually not a primary pollutant. What 

that means is that ozone is actually formed by different precursors. 

So what happens is in the presence of heat and sunlight and volatile organic compounds and nitrogen oxides, all of that mixes and 

there’s a chemical reaction that actually forms ozone. That’s why 
126 

it’s one of the trickier pollutants to manage because it’s not a primary pollutant; it’s a secondary pollutant. That’s what we call a 

secondary pollutant. 

Mr. ROHRABACHER. Coming from southern California, I can still 

remember people talking about ozone. Are we healthier? Did we 

handle that with what we did on our engines? Because I know that 

cost a lot of money in terms of gas mileage, et cetera, but are we 

healthier because of that now? 

Dr. CRAFT. You are healthier because of that. If you look, there’s 

actually work done in southern California by a prominent researcher Gauderman, who’s actually been able to demonstrate the 

improvement in children’s health because of the reduction in air 

pollution generally. So we know that these controls work and that 

they lead to better health outcomes. 

Mr. ROHRABACHER. Well, we know generally, but I was thinking 

about ozone and—do we know—does—is there someone else want 

to jump in on that? 

Ms. RATH. Congressman, I’ll be glad to say that we appreciate 

the controls and the impact it’s making, particularly in the NOx because in our area the VOC is a very small contributor to our ozone 

precursors. 

I would like to address your question about the oil and gas, and 

I have to salute the energy companies that operate in the Eagle 

Ford Shale. Last year, the highest production of oil came out of the 

Eagle Ford Shale, particularly Karnes County, more than any place 

else in the world. And the energy companies that are operating in 

south Texas have made significant investments in technology to 

really respect people’s health and to take those measures to really 

lower their emissions. 

So the emissions from the oil and gas industry in our area is a 

very small contributor. I certainly can’t speak to what’s going on 

in the West, but I want to be very clear that that is not a primary 

contributor in our area at all. 

Mr. ROHRABACHER. Well, what is the primary contributor? 

Chairman BIGGS. Unfortunately, the gentleman’s time is expired. 

Mr. ROHRABACHER. Oh, pardon me. 

Chairman BIGGS. Sorry. Sorry, Mr. Rohrabacher. 

I now recognize the gentleman from Virginia, Mr. Beyer. 

Mr. BEYER. Thank you, Mr. Chairman. Thank you all very much 

for being with us. 

I would like to talk for a minute about the ‘‘once in, always in’’ 

policy legal history. And, Dr. Craft, EPA’s repeal memo claims that 

the ‘‘once in, always in’’ policy violates the plain language of the 

Clean Air Act. Was the policy ever challenged in the courts in its 

27-year history? 

Dr. CRAFT. The policy has been around for roughly a quarter of 

a century, and as far as I know, it has—actually, I’m not sure 

about that, whether it’s actually been legally challenged. 

Mr. BEYER. It was a rhetorical question because at least our evidence shows that it’s never been questioned in court. And what’s 

remarkable is that the new EPA Assistant Administrator William 

Wehrum filed suit against the EPA 31 times when he was in private practice, and he’s the primary person behind this memo, and 

yet he never challenged it as a private citizen either. 
127 

You know, the decision to increase hazardous air pollutants, carcinogens, and neurotoxins is completely irresponsible, and this decision is even more reckless today given that we know we can successfully control them with operating control devices, long-range 

applicable regulations. And it’s the responsibility of the EPA to 

continue to guard the health and human environment against potential harms. And that’s why I led a letter with Congresswoman 

Dingell with 87 cosponsors asking Administrator Pruitt to reinstate 

these longstanding toxic air pollution protections. And, Mr. Chairman, I ask that this be admitted to the record. 

Chairman BIGGS. Without objection. 

[The information follows:]*************** COMMITTEE INSERT 

*************** 

Mr. BEYER. Dr. Clark—Dr. Craft rather, there have been cases 

made well by your three panelists about background radiation or 

background ozone levels. And one of the—and you’ve pointed out 

in the questions from Chairman Smith that in fact EPA, the Clean 

Air Act, already takes this into consideration. But one of the questions was that a demonstration can only be submitted after three 

years of the area not meeting the standard. This was for Yuma 

particularly. Is three years too long? 

Dr. CRAFT. The reason—oh, sorry. The reason for that three-year 

requirement is that they don’t—EPA does not want to penalize an 

area for having sort of a bad year, so what they do is they average 

the previous three years to account for any anomalies that might 

exist. So that’s the purpose of the 3 years. 

I just wanted to go back and mention your ‘‘once in, always in’’ 

question. One of the things that we’ve done as an organization is 

we’ve gone through to analyze the potential outcome of reversing 

such a policy. One of the things that can happen is that this policy—this loophole that’s been created applies to major sources of 

hazardous air pollutants under section 112, and it allows these facilities to reclassify themselves as area sources if they dip below 

the threshold value, which is 10 tons per year for a single hazard 

air pollutant or 25 tons per year of a combination of hazardous air 

pollutants, whereas before, once they were classified as major, they 

had to continue applying those controls regardless of those emissions. 

So in this example a source that had been previously classified 

as a major for lead and other HAPs, if they went down to one ton 

per year, they could under the new policy stop applying those maximum achievable control technologies and then increase its emissions back to 9 tons per year, still avoiding being classified as a 

major source. So that is a critical issue. 

And actually, in 2017, EPA issued a fact sheet stating that 1.7 

million tons of hazardous air pollution was prevented because of 

that policy, so that’s an important issue I just—— 

Mr. BEYER. Okay. 

Dr. CRAFT. —wanted to go back and clarify. 

Mr. BEYER. Okay. Thank you. I have one more key issue. Administrator Pruitt on May 9 issued a memo implying that EPA might 

consider costs when setting NAAQS standards despite settled Supreme Court precedent. The standards must be based on public 

health. And I don’t think I’ve ever quoted Justice Scalia positively 
128 

before, but he wrote the unanimous decision from the Court that 

only public health factors may be considered. And I’d like to submit 

another letter for the record signed by 71 Members, Mr. Chairman, 

objecting to this. But I’d love your perspective, Dr. Craft. 

Chairman BIGGS. Admitted without objection. 

Mr. BEYER. Thank you. 

[The information appears in Appendix I] 

Dr. CRAFT. Yes, that is totally outside the specific language of 

the Clean Air Act to require cost to be considered. Costs are considered in another part of—in terms of implementation, not in terms 

of setting the policy—the scientific standard itself. 

Mr. BEYER. Great. Thank you. Mr. Chairman, I yield back. 

Chairman BIGGS. The gentleman yields back. 

I recognize the gentleman from Texas, Mr. Babin. 

Mr. BABIN. Thank you, Mr. Chairman. And thank you, witnesses, 

for being here. 

Mr. Stella, in your testimony you also state that for the areas 

that have seen elevated levels of ozone over the last ten years, an 

increase in background ozone is likely to blame. Can you please 

elaborate how you know this to be true? 

Mr. STELLA. Thank you for the question. 

Mr. BABIN. Yes, sir. 

Mr. STELLA. Specifically, we don’t have values that would allow 

us to interpret how much of the increased international or background contribution is there, but what we do recognize is that 

when we run our photochemical models and look at our source apportionment studies, which basically tags the input to the model, 

follows it through time and space, and then we look at the ozone 

concentrations at each monitor, we’re seeing that as anthropogenic 

emissions are being applied locally in our States, the ozone concentrations are being offset by an increase from this background 

contribution component. Now, whether or not that’s all international anthropogenic or international biogenic is uncertain, but 

the studies seem to indicate that, based on our source apportionment runs, the relative percentage of the background ozone is increasing compared to the reductions we’re seeing from anthropogenic controls domestically. 

Mr. BABIN. Okay. Well, you had mentioned modeling. Would you 

discuss some of the improvements being made to modeling through 

collaborations like the one between NOAA, NASA, and EPA? 

Mr. STELLA. Absolutely. Some of the work that’s ongoing at those 

agencies include looking at the performance evaluation of the models. Are we adequately predicting and projecting levels of background ozone. And so, for example, along the West Coast of the 

United States where we have a very clean boundary and we can 

measure ozone as it comes across the Pacific, studies are being conducted with satellites, with ozone sons, with high-elevation monitors, and so we’re trying to capture with better accuracy the 

amounts of emissions that are coming in without a domestic anthropogenic or biogenic influence. And so those are some of the 

studies that are being conducted, in addition to looking at the air 

chemistry involved with the ozone formation as it’s developed over 

the oceans, as well as attempting to better understand the impact 
129 

of wildfires and biogenics, and so looking at the inputs that go into 

our modeling. 

Mr. BABIN. Okay. Thank you. And then, Ms. Rath, reducing 

ozone emissions can stifle economic development in a region because of the impacts to construction industry and businesses. Do 

you have any sense of how much it costs for your area to comply 

with these regulations? 

Ms. RATH. Yes, sir. Thank you. As I had mentioned, we had a 

study that was performed by an economist at St. Mary’s University, and he said that with a marginal designation, our eight-county MSA would have costs at a minimal level of $117 million a year 

up to a maximum of a little over $1 billion a year, so that’s the 

cost annually if we were to go into a marginal status of nonattainment. And then we also have the figures for moderate. 

And if I may, Congressman, I would like to say—— 

Mr. BABIN. Sure. 

Ms. RATH. —that we have certainly seen an increase in the foreign transport in our area. In 2015, we were about 29 percent foreign, and it’s increased in 2017 to 38 percent foreign. So we’re 

clearly seeing a much larger impact of foreign transport, and it’s 

because of the improvements that we have done locally with the 

local generation going down, so that percentage that’s foreign has 

certainly increased at least in our area. 

Mr. BABIN. Okay. Thank you very much. And then, Mr. 

Franquist, would you please explain the potential economic impacts 

on a rural community if it’s determined to be in nonattainment for 

ozone? 

Mr. FRANQUIST. Thank you, and good question. Unfortunately, I 

don’t have the same numbers for an area like Yuma. What I can 

say is, thanks to the good work that Texas has done, we actually 

scaled a similar economic study for Phoenix’s nonattainment area, 

and that’s somewhere in the neighborhood of $80–100 million, 

again, per year annually. 

For a place like Yuma, I think the cost you have to look in is 

it voided businesses coming into the area? We know that in the 

Phoenix area we lost four large businesses coming into the nonattainment area just to avoid the offsets and layer requirements. 

So, unfortunately, I can’t give you a dollar sign, but I can say it’s 

significant in terms of job loss or job avoidance. 

Mr. BABIN. Yes, so I mean it’s definitely an impact. 

Mr. FRANQUIST. Correct. 

Mr. BABIN. A number of businesses just won’t come into that 

area because of the nonattainment. 

Mr. FRANQUIST. That’s correct. 

Mr. BABIN. Okay. Well, I think my time’s expired. Thank you, 

Mr. Chairman. 

Chairman BIGGS. Thank you. The gentleman yields. 

And we’re going to turn to the gentleman from California, Mr. 

Takano. 

Mr. TAKANO. Thank you, Mr. Chairman. 

Dr. Craft, I’m—this probably has been asked, but I want to ask 

it again. The current law permits mainly health concerns and 

science to drive ozone standards, is that correct? It’s not economic 

impact, is that correct? 
130 

Dr. CRAFT. Correct. 

Mr. TAKANO. And that’s been—I think Mr. Beyer submitted for 

the record Supreme Court decisions which reaffirmed that. And I 

know that even the majority in this House respects the first branch 

of government, the legislative branch, as the maker of the laws, 

and it’s, I think, inappropriate for the EPA to decide if they’re 

going to use some other criteria to decide the levels of ozone that 

are permissible in regulation. 

Dr. CRAFT. Yes. 

Mr. TAKANO. Yes. Are you familiar with the Inland Empire region of southern California and the work of the Southern California 

Air Quality Management District in improving air quality in my region? 

Dr. CRAFT. Yes. 

Mr. TAKANO. What can you say about that over the past 20, 30 

years? 

Dr. CRAFT. I can say that California has been a leader in developing air quality strategies to reduce emissions. California has 

some unique challenges that don’t exist anywhere else in the country, and they have taken that challenge on. It’s one of the most innovative, creative States in terms of trying to get those reductions. 

What California has done with regard to clean car standards is tremendous. We had just this week actually the State of Colorado 

signing on to California’s clean car standards. So California has 

been a model leader for implementing strategies to reduce pollutants like ozone. 

Mr. TAKANO. I can say from my anecdotal personal experience 

that I experienced as a child in the ’60s and ’70s frequent days of 

what we called smog alerts where kids were not allowed to go out 

and play because—I think it was because of ozone, the ozone layers—levels were so high. And I can remember at night my lungs 

feeling that burning sensation, and that those days have been reduced greatly. And I think that’s in great deal—a part—we can attribute that to the aggressive efforts of the—of the Air Quality 

Management District in California. 

Dr. CRAFT. Absolutely. And I would say that there’s still more 

work to do. If you review the State of the Air 2018, it’s estimated 

that 41 percent of the population of the United States lives in areas 

that exceed health-based standards for pollutants like ozone and 

particulate matter. 

Mr. TAKANO. And my district in the Inland Empire, we experience high volumes of traffic from trucking and also other mobile 

sources, but we’re seeing an increase of truck traffic as a result of 

products being shipped to and from logistics centers in my area. If 

public health were not the primary concern in setting ozone standards, would districts like mine have more to worry about when it 

comes to air quality and public health? 

Dr. CRAFT. I think we have to use sound science to establish 

these polices. We can’t use anything else. Using anything else jeopardizes the integrity of the science. That’s why we use science. 

That’s why it’s so important. We cannot have policy-led science. We 

need to have science-led policy. 

Mr. TAKANO. Thank you very much for that. You know, it’s my 

understanding, Dr. Craft, that the Clean Air Act contains a num-
131 

ber of mechanisms that allow EPA to address high background levels of ozone, specifically allows for the exclusion of exceptional 

events like wildfires and the transport of air pollution from overseas that contributes to higher ozone levels. We talked about the 

good ozone and bad ozone. 

This exceptional-events rule was revised in 2016 to address 

stakeholder concerns about the rule’s clarity and efficiency. Could 

you share with us how and why these types of mechanisms operate 

to the benefit of public health? 

Dr. CRAFT. Sure. EPA has actually done a lot of work over the 

last couple of years trying to address tools, getting tools in place 

to help manage ozone. I have a recent white paper from the agency 

outlining some of the tools that are available to manage ozone 

exceedances from things like exceptional events and background 

ozone. So some of those tools are the exceptional-event exclusions 

that you mentioned. Small nonattainment area boundaries for sites 

minimally impacted by nearby sources is another. Rural transport 

areas is another. And then international transport provisions mentioned here, the 179B, are just a couple of the tools that are in 

place. 

EPA does work hand-in-hand with the States to try to come up 

with policies that work for those States. It’s not—it’s under an 

agreement known as cooperative federalism. We want the Federal 

Government and the States working hand-in-hand toward the common goal of protecting public health. That’s why the EPA is there. 

Mr. TAKANO. Mr. Chairman—— 

Chairman BIGGS. The gentleman’s time is expired. 

Mr. TAKANO. Thank you. 

Chairman BIGGS. Thank you, sir. 

I now recognize myself for five minutes for questions. 

I want to begin with a statement regarding the memo that’s received such attention today. Administrator Pruitt, in his memo on 

the NAAQS, requested that the Clean Air Scientific Advisory Committee compile data on background ozone. As we’ve just heard in 

the testimony, that request is in line with Clean Air Act and its 

interpretation by the courts, including such cases as American 

Trucking Associations v. EPA. The Administrator of EPA is permitted by law to consider background ozone in NAAQS implementation. 

And with that, Mr. Franquist, Yuma County, bordered by Mexico, bordered by California, a rural county, very few big businesses, 

very few even medium-sized businesses in it, is it possible for 

Yuma County to reach attainment even under diligent efforts to 

offset emissions? 

Mr. FRANQUIST. Mr. Chairman, I think it’s unlikely, given the 

sources. When we look at the National Emissions Inventory for 

volatile organic compounds and NOx, the two precursors for ozone, 

we’re looking at something in the neighborhood of two percent for 

VOCs and five percent from vehicles—from essentially anthropogenic sources in the Yuma area. So you likely could remove all industrial activities in the Yuma area, but because of the influence 

of international sources, you would likely still have a challenge of 

attaining the standard. 
132 

Chairman BIGGS. So we hear about the impacts of ozone on 

health, but we just talked about you could actually eliminate all industrial outputs and still fail to meet the NAAQS requirement levels. So that would further induce poverty into that area. And so 

what’s the health impacts of poverty? What have the studies said 

about that? 

Mr. FRANQUIST. Mr. Chairman, we’ve referenced a couple today 

and we’ve supplied several in the past, but, again, the connection 

for poverty and ill health is enormous. We know in areas like 

Yuma when we’re 19 percent unemployment, what that does is it 

adds a burden to healthy foods, access to health care, so it goes 

hand-in-hand. And so, again, there’s numerous academic articles 

linking public health issues and the economy, and so, again, that’s 

why we don’t challenge that ozone in and of itself is a problem. 

However, when that ozone’s coming from somewhere else and the 

Clean Air Act is designed to impact negatively those local economies, now those impoverished areas have a one-two punch. And so, 

again, we think it’s really valid to begin to look at how the Clean 

Air Act is designed to protect public health and the environment 

but to also relieve some of those areas of some of the significant 

economic impacts that go with the 179B demonstration. 

Chairman BIGGS. And, Mr. Stella, in your testimony you discussed a diminishing rate of return on U.S.-controlled programs 

impacting air quality as the incremental cost of every ton of emissions increases. Can you elaborate on that, please? 

Mr. STELLA. Certainly. Thank you for the question. In essence, 

what we’re seeing is that, as a series of controls have already been 

historically put in place and we see domestic ozone reduced from 

the anthropogenic sources that we have control over, and an everincreasing relative contribution of uncontrollable sources, whether 

or not the international transport or background or stratospheric 

intrusions and the like. As we try to get each additional ton reduced to improve our air quality, the cost becomes higher and higher, and it’s simply because we’re not getting the same response out 

of a reduction of one ton of NOx or VOC, for example, to reduce 

an equal amount of ozone concentration. And so as we get lower 

and lower and we see a greater percentage of uncontrollable 

sources dominate what our ambient conditions are, it’s going to 

cost more to reduce less. 

Chairman BIGGS. Thank you. I would like to elaborate on that 

just for a second. As we see the diminishing return economically, 

do you see it—is there a diminishing return as far as health conditions and improvement in health as you move from, say, 70 NOx 

down to 69, for instance? 

Mr. STELLA. I’m not sure that that’s a question for me, not being 

my area of expertise, but as a scientist, I would believe that, as you 

see the ozone levels decreasing, you see improvements in health. 

Chairman BIGGS. Is there a statistical—well, you just said it’s 

not your area, so I’m just wondering if there’s a statistical diminution, but regardless, we have reached basically the end of our time 

today. I appreciate all of you for coming and sharing your testimony. I think it’s important for us as this allows for a robust discussion, and we need a robust discussion on these issues. And 
133 

there’s a lot of considerations, a lot of variables that we have to 

take into account. 

I appreciate those on both sides of the aisle for being here and 

participating today, and with that, we’re adjourned. 

[Whereupon, at 11:43 a.m., the Subcommittee was adjourned.] 

(135) 

Appendix I 

ADDITIONAL MATERIAL FOR THE RECORD
136 

LETTER SUBMITTED BY COMMITTEE CHAIRMAN

LAMAR S. SMITH
137 

The Honorable Scott Pruitt 

May 11,2018 

Page2 

adversely affect Bexar County's ozone levels.3 Unfortunately, the Technical Support Document 

(TSD) attached to that March 19 letter also contained significant legal and factual errors that 

underlie the proposed modification to my recommendation. Once those errors are corrected, the 

propriety of designating Bexar County as in attainment becomes clear. 

A. As a Matter of Law, EPA Has Discretion to Designate Bexar County as In 

Attainment 

The TSD misstates the law. It asserts that "EPA must designate as nonattainrnent any 

area that violates the NAAQS." TSD at 6 (emphasis added). Elsewhere, the TSD suggests that 

this result is compelled by Section 107(d) of the Clean Air Act. See id. at 2. 

That is not true. As I explained in my previous letter, EPA's discretion is recognized in 

the plain text of the CAA, judicial interpretations of the CAA, and EPA's past practices under 

the CAA. It would be legally erroneous for EPA to ignore these authorities and to follow instead 

a nonbinding guidance document issued by the previous Administration. 

l. First consider the text of the CAA. Section 1 07( d) grants EPA significant 

discretion in making designation decisions. It establishes a two-step process in which Governors 

make initial recommendations and then the Administrator "make[s] such modifications as the 

Administrator deems necessary." 42 U.S.C. § 7407(d)(l)(B)(ii). Section 107 "says nothing of 

what precisely will render a modification 'necessary'" and thus leaves the necessity of 

modifications to EPA's discretion. Catawba Cty., NC. v. EPA, 571 F.3d 20,35 (D.C. Cir. 

2009). 

2. Courts likewise have recognized this discretion when interpreting materially 

identical language in related sections of the CAA. For example, section 231 of the CAA 

empowers EPA to regulate emissions from aircraft and requires the Administrator to "issue such 

regulations with such modifications as he deems necessary." 42 U.S.C. § 7571(a)(3). The D.C. 

Circuit described this "deems necessary" language, which Section 1 07 also contains, as an 

"explicit and extraordinarily broad" delegation of authority. Nat 'I Ass 'n of Clean Air Agencies v. 

EPA, 489 F.3d 1221, 1229 (D.C. Cir. 2007). "Finding nothing in 'the text or structure of the 

statute to indicate that the Congress intended to preclude the EPA from considering [factors other 

than air quality],' [the court] refused 'to infer from congressional silence an intention to preclude 

the agency from considering factors other than those listed in a statute."' I d. at 1230 (quoting 

George E. Warren Corp. v. EPA, 159 F.3d 616,623-24 (D.C. Cir. 1998)). 

So too here. Section 1 07 grants EPA broad discretion to consider factors beyond 

monitoring data, including Bexar County's projected improvements in air quality and the adverse 

effect of foreign emissions, as the case law cited in my previous letter demonstrated. See, e.g., 

Sierra Club v. McCarthy, No. 13-cv-3953, 2015 WL 889142, at *1 (N.D. Cal. Mar. 2, 2015), 

ajf'd sub nom. Sierra Club v. North Dakota, 868 F.3d 1062 (9th Cir. 2017) (recognizing "EPA's 

3 Texas: San Antonio, Intended Area Designations for the 2015 Ozone NAAQS, Technical Support Document at 21, 

https://www.epa.gov/sites/production/files/2018-03/documentsitx sanantonio 120d tsd draft 3-2018 r6.pdf. 

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discretion to determine, based on available information, whether an area is in 'attainment' or 

'nonattainment' with the [relevant] air quality standard, or whether the area is 'unclassifiable' ''). 

I am aware of no contrary authority4 

3. EPA has long used discretion to avoid nonattainment designations. When EPA 

considers changing an area's previous designation, it exercises discretion regarding whether to 

redesignate an area as in nonattainment. For example, under the Early Action Compact (EAC) 

program, EPA agreed to use its discretion to avoid redesignating EAC areas as "nonattainment" 

in exchange for local governments making voluntary improvements to their air quality: 

[I]n deciding whether to redesignate an EAC area to nonattainment, EPA will 

consider the factors in section 107(d)(3)(A) of the CAA. I fan EAC area 

continues to meet its compact milestones, EPA believes those factors should 

weigh in favor of not redesignating the area to nonattainment immediately, but 

rather waiting to see if the programs the area puts in place will bring it back into 

attainment. 

Early Action Compact Areas With Deferred Effective Dates, 69 Fed. Reg. 23,858, 23,871 (Apr. 

30, 2004). In other words, EPA "deem[ ed] necessary" a wait-and-see approach for 

redesignations that allowed areas not meeting the NAAQS to avoid the regulatory burdens of a 

nonattainment designation while they were making progress toward cleaner air. 

EPA should do the same here. That EPA has exercised discretion in the redesignation 

process under Section I 07( d)(3) weighs heavily in favor of exercising discretion in the 

designation process under Section 107(d)(l) because the two provisions are similar in both text 

and purpose. See 42 U.S. C.§ 7407(d)(3)(C) ("[T]he Administrator shall promulgate the 

redesignation, if any, of the area or portion thereof, submitted by the Governor in accordance 

with subparagraph (B), making such modifications as the Administrator may deem necessary, in 

the same manner and under the same procedure as is applicable under clause (ii) of paragraph 

(l)(B) [the provision at issue here]."). 

4. Statutory text, court decisions, and EPA's previous actions all make clear that 

EPA has discretion to designate Bexar County as in attainment. Against those authorities, EPA's 

March 19 response cited a non-binding policy memorandum, prepared under the previous 

Administration, suggesting that EPA lacks discretion over designations. 

4 EPA should also consider that one regulatory monitor and numerous non-regulatory monitors all show that ozone 

levels in Bexar County satisfy the 2015 NAAQS. Your response asserts that the data "do not meet EPA quality 

assurance criteria and cannot be used for regulatory purposes," TSD at 21, but it makes no effort to distinguish the 

multiple recent instances in which EPA has considered similar data. "[W)hen an agency takes inconsistent positions, 

as [EPA] did here, it must explain its reasoning." Gulf Power Co. v. FERC, 983 F.2d 1095, 1101 (D.C. Cir. 1993). 

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But that unreasoned ipse dixit is not the law. The memorandum itself recognizes that 

"[a ]ny guidance contained herein is not binding on states, tribes, the public or the EPA. "5 As 

former Attorneys General, we both know that the previous Administration's legal assertions 

cannot be taken at face value. For that reason, more than a year ago, President Trump ordered 

EPA to review existing environmental policies to ensure that they "comply with the law." 

Presidential Executive Order on Promoting Energy Independence and Economic Growth § 1 (e) 

(Mar. 28, 2017). More recently, the President specifically directed you to "evaluate EPA's 

existing rules, guidance, memoranda, and other public docmnents relating to the implementation 

ofNAAQS." Presidential Memorandum for the Administrator of the Environmental Protection 

Agency§ 9 (Apr. 12, 2018). I respectfully urge you to follow the President's lead, 

independently review EPA's legal authority, and for the reasons outlined above, conclude that 

EPA has the discretion to designate Bexar County as in attainment. 

Failing to recognize and exercise EPA's discretion in this regard would render any 

nonattainment designation "arbitrary, capricious, an abuse of discretion, or otherwise not in 

accordance with law." 5 U.S.C. § 706(2)(A). "[A) court 'can compel an official to exercise his 

discretion where he has obviously failed or refused to do so.'" NAACP v. SecyofHousing & 

Urban Devel., 817 F.2d 149, 160 (1st Cir. 1987) (quotingMastrapasqua v. Shaughnessy, 180 

F.2d 999, 1002 (2d Cir. 1950)); see also United States ex rei. Accardi v. Shaughnessy, 347 U.S. 

260, 268 (1954) ("[W]e object to the Board's alleged failure to exercise its own discretion, 

contrary to existing valid regulations."); Bargmann v. Helms, 715 F.2d 638,641 (D.C. Cir. 1983) 

("[W]e are presented with an agency's refusal to exercise its discretion, based on its belief that it 

has no power to do otherwise .... It is well within the tradition of our review of agency action on 

petitions for rulemaking to make an independent inquiry into an agency's allegation that it lacks 

the statutory authority to act."). 

B. Foreign Emissions Caused Bexar County to Exceed the 2015 Ozone NAAQS 

The TSD also misunderstands the relevant facts. As I explained in my February 28 letter, 

"[r]ecent photochemical modeling shows that emissions from foreign sources likely contribute 

10-24 ppb of ozone to eight-hour ozone concentrations in Bexar County. Without these foreign 

emissions, Bexar County's ozone levels would be well below the 2015 NAAQS."6 

1. The TSD downplays the significance of these foreign emissions because they 

include both man-made and naturally occurring foreign emissions. TSD at 21. The TSD' s 

objection fails for two independent reasons. First, considering all foreign emissions, regardless 

of cause, is the more relevant analysis. Second, considering man-made foreign emissions alone, 

as the TSD suggests, does not change the result. In the absence of foreign man-made emissions, 

Bexar County would have satisfied the 2015 ozone NAAQS. 

5 Memo. from Acting Assistant Administrator Janet G. McCabe to Regional Administrators re Area Designations for 

the 2015 Ozone National Ambient Air Quality Standards at 9 (Feb. 25, 2016), https://www.eoa.gov/sites/production/ 

files/20 16-02/documents/ozone-designati ons-guidance-20 15 .pdf (emphasis added). 6 Letter from Gov. Abbott to Administrator Pruitt at 6 (Feb. 28, 2018), https://www.regulations.gov/document?D= 

EPA-HQ-OAR-2017-0548-0297. 

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There is no legitimate reason to punish Bexar County for emissions that it cannot control, 

regardless of whether those emissions are naturally occurring or man-made. For that reason, 

EPA has traditionally defined background ozone, which is not subject to regulatory controls, as 

including all foreign emissions as well as naturally-caused domestic emissions.7 There is no 

reason to exclude consideration of naturally occurring foreign emissions. 

My letter called attention to both the impact of foreign emissions in particular and the 

problem of background ozone in general. Consideration of total foreign emissions is not too 

broad; in fact, a broader-still consideration of all background ozone is appropriate. Consistent 

with EPA's historical understanding of background ozone, EPA should consider that only 49 

percent of relevant Bexar County ozone emissions come from domestic man-made sources.8 In 

other words, neither EPA nor Bexar County could regulate a majority of the ozone affecting 

Bexar County. 

2. Moreover, the TSD is wrong to suggest that foreign man-made ozone is 

insignificant. In fact, EPA has previously estimated the effects of foreign man-made emissions 

on ozone levels, and EPA's own analysis suggests that Bexar County would have met the 2015 

ozoneNAAQS if not for foreign man-made ozone. 

EPA estimated the effect of "global methane emissions related to recent human activity 

as well as anthropogenic emissions outside of North America" on Bexar County as 8-10 ppb. 9 

EPA then noted that the increase in methane was probably responsible for 4-5 ppb of ozone 

nationwide. 10 That leaves 4-5 ppb that EPA attributed to man-made emissions from outside 

North America. Of course, that estimate understates total foreign man-made emissions by 

omitting man-made emissions from Mexico, Canada, and other foreign countries in North 

America. Because Bexar County exceeded the 2015 ozone NAAQS by only 3 ppb, EPA's own 

data suggest that it would have met the 2015 ozone NAAQS if foreign man-made emissions had 

not interfered. 

3. Instead of undertaking this analysis, the TSD claims that "the impacts from 

manmade emissions from Mexico is on the order ofless than 1 ppb." TSD at 21. First, that 

statement is factually incorrect. Only part of Mexico was included within the modeling domain, 

meaning that Mexican emissions were split between what the model labelled "Mexico" and what 

7 EPA, Implementation of the 2015 Primary Ozone NAAQS: Issues Associated with Background Ozone at 2 (Dec. 

30, 2015), https://www.epa.gov/sites/production/files/2016-03/documents/whitepaper-bgo3-final.pdf; see also 

Presidential Memorandum for the Administrator of the Environmental Protection Agency (Apr. 12, 2018) (defining 

ozone "background levels" as the "levels associated with natural sources or emissions originating outside of the 

United States"). 

' !d. at 22 (Table 2a). 9 EPA, Policy Assessment for the Review of the Ozone National Ambient Air Quality Standards (Aug. 2014) at 2A29, https://www3.epa.gov/ttn/naaqs/standards/ozone/data/20140829pa.pdf(estimating 6-15 ppb for the United 

States as a whole and noting that 8-10 ppb was the "most frequent bin"); id. at 2A-31, Figure 8b (showing Bexar 

County as 8-10 ppb ). 10 Id. at 2A-29. 

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the model labelled "Boundary conditions/Intemational."11 As a result, the TSD's estimate is too 

low. Second, the TSD's focus on Mexico, to the exclusion of all other foreign sources, cannot be 

squared with the President's recent order that EPA "not limit its considerations to emissions 

emanating from Mexico or Canada, but rather consider[], where appropriate, emissions that may 

emanate from any location outside the United States." Presidential Memorandum for the 

Administrator of the Environmental Protection Agency§ 4(b) (Apr. 12, 2018). The TSD's 

Mexico-only analysis, in addition to being wrong, is irrelevant. 

In short, Bexar County would have already met the 2015 ozone NAAQS if it did not have 

to contend with foreign emissions. EPA's preliminary conclusion to the contrary was premised 

on a fundamental misunderstanding of the data. 

ll. Alternatively, EPA Should Designate Bexar County as Unclassifiable 

EPA is considering whether to withdraw the 2015 NAAQS. In fact, EPA has used that 

potential withdrawal to justify staying a challenge to the lawfulness of the 2015 NAAQS. See 

Respondent EPA's Third Status Report, Doc. No. 1711911, Murray Energy Corp., et al. v. EPA, 

No. 15-1385 (D.C. Cir. Jan. 8, 2018) (consolidated with 15-1392, 15-1490, 15-1491 & 15-1494). 

As I previously explained in my February 28 letter, EPA should not proceed with designations 

while the fate of the 2015 NAAQS is still uncertain. 

Legal uncertainty surrounding the 2015 NAAQS counsels in favor of, at worst, an 

unclassifiable designation. Because EPA cannot give effect to an unlawful rule, "available 

information" is insufficient to establish the 2015 NAAQS as "the national primary or secondary 

ambient air quality standard" for purposes of Section 107, much less can "available information" 

show that Bexar County "is not meeting" that standard. 42 U.S.C. § 7407(d)(l)(A)(iii). 

In addition, considerable factual uncertainty means that Bexar County "cannot be 

classified [as nonattainment] on the basis of available information." !d. As has been recently 

reported, a coal-fired power plant in Bexar County is planning to cease operations by the end of 

this year. 12 Because this plant is upwind of the relevant monitors, its suspension of operations is 

likely to significantly improve ozone levels. While such a major change is pending, a 

nonattainment designation based on soon-to-be-out-of-date information would be unreasonable. 

See, e.g., Permian Basin Petrol. Ass 'n v. Dep 't of the Interior, 127 F. Supp. 3d 700, 716-17 

(W.D. Tex. 2015) (failure to consider "updated ... numbers" was arbitrary and capricious 

11 Letter from Gov. Abbott to Administrator Pruitt at App'x C, pp.1-2 (Feb. 28, 2018), https://www.regulations.gov/ 

document'?D~EPA-HO-OAR-2017-0548-0297. Moreover, the TSD erroneously claims that the modeling cited in 

my previous letter inappropriately includes ozone "generated from emissions within the US and recirculated into the 

domain." TSD at 21. As the Texas Commission on Environmental Quality has explained, because the modeling 

boundary "is at least 200 miles away from any continental U.S. border," it is likely "that emissions and ozone 

outside this boundary did not originate within the continental United States." Letter from Gov. Abbott to 

Administrator Pruitt at App'x C, p.l (Feb. 28, 2018), https://www.regulations.gov/document?~EPA-HQ-OAR2017-0548-0297. Similarly, the impact of Hawaiian and Alaskan emissions is likely negligible. 

"U.S. Energy Information Administration, Natural Gas Weekly Update (Mar. 14, 2018), https://www.eia.gov/ 

naturalgaslweekly/archivenew ngwu/2018/03 15/ ("Units 1 and 2 at the 840-MW IT Deely coal-fired plant are 

planned for retirement by the end of this year."). 

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because "reliance on out-of-date or incomplete information may render the analysis of effects 

speculative and uncertain" (quoting City of Dallas v. Hall, 562 F.3d 712,720 (5th Cir. 2009))); 

Sierra Club v. Babbitt, 15 F. Supp. 2d 1274, 1284 (S.D. Ala. 1998) (agency finding was 

"arbitrary and capricious" due to reliance "on insufficient, inadequate, and out of date data"). 

Under no circumstances should Bexar County receive a designation worse than 

unclassifiable. 

III. EPA Should Defer the Effective Date of Any Nonattainment Designation 

If, contrary to my recommendation, EPA chooses to designate Bexar County as in 

nonattainment, EPA should at least defer the effective date of that designation. 

In the past, EPA has deferred effective dates for nonattainment designations when 

localities have demonstrated a willingness and an ability to improve their air quality without 

additional federal intervention. Through the EAC program discussed above, EPA deferred the 

effective date of nonattainment designations in exchange for local governments agreeing to clean 

their air more quickly than the CAA would otherwise require. 

Such a deferral would be a mutually beneficial solution that advances cooperative 

federalism, which you have rightly described as "key to maintaining clean air." 13 First, and most 

important, citizens get cleaner air more quickly with fewer economic drawbacks. Second, States 

and localities avoid the bureaucratic nightmares that follow from nonattainment designations and 

maintain "primary responsibility for assuring air quality." 42 U.S.C. § 7407(a). Third, EPA is 

able to meet its legal obligation to "promulgate the designations ... as expeditiously as 

practicable" while advancing the CAA's goal of clean air. !d.§ 7407(d)(l)(B)(i). 

For these reasons, EPA has consistently reaffirmed the legality of deferring the effective 

date of a nonattainment designation. See Final 8-Hour Ozone National Ambient Air Quality 

Standards Designations for the Early Action Compact Areas, 73 Fed. Reg. 17,897, 17,899 (Apr. 

2, 2008); Extension of the Deferred Effective Date for 8-Hour Ozone National Ambient Air 

Quality Standards for Early Action Compact Areas, 70 Fed. Reg. 50,988, 50,992 (Aug. 29, 

2005); Air Quality Designations and Classifications for the 8-Hour Ozone National Ambient Air 

Quality Standards; Early Action Compact Areas With Deferred Effective Dates, 69 Fed. Reg. 

23,858, 23,869-70 (Apr. 30, 2004). 

As your response acknowledged, Bexar County is projected to meet the 2015 ozone 

NAAQS by 2020 without additional federal intervention. 14 Local1eaders are eager to clean their 

u EPA News Release, EPA Advances Cooperative Federalism through Designation Process for Sulfur Dioxide and 

Ozone Standards (Dec. 22, 20!7), https://www.epa.gov/newsreleases/epa-advances-cooperative-federalism-throughdesignation-process-sulfur-dioxide-and. 

14 Moreover, EPA itself has projected that all three of Bexar County's regulatory monitors will be well below 70 

ppb, even in the absence of additional local actions, by 2025. EPA Regulatory Impact Analysis of the Final 

Revisions to the National Ambient Air Quality Standards for Ground-Level Ozone at 2A-6! (Sept. 20!5), 

https:/ /www .epa.gov/sites/production/files/20 !6-02/ documents/20 151 001 ria.pdf. 

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air and have already implemented many successful reforms to do so. Deferring the effective date 

of any nonattainment designation would provide local leaders with the regulatory flexibility 

necessary for efficient reduction of Bexar County's ozone levels. 

In fact, EPA and Bexar County have successfully used a deferred effective date to spur 

air quality improvements before. Under the EAC program, Bexar County "agreed to reduce 

ground-level ozone pollution earlier than the CAA would require" and then "successfully 

attained" the 1997 ozone standard. TSD at 5 n.1 0. As a result, Bexar County "was ultimately 

designated as attainment." TSD at 20 n.20. Bexar County's history of success with deferred 

effective dates strongly supports a similar approach for the 2015 ozone NAAQS. 

* * * 

In its March 19 letter, EPA committed to "implementing the [NAAQS] using a common 

sense approach that improves air quality and minimizes the burden on state and local 

governments." No common-sense approach could support immediately burdening Bexar County 

with the regulatory consequences of an effective nonattairunent designation. I therefore reiterate 

my recommendation that Bexar County should be designated as in attainment of the 2015 ozone 

NAAQS. 

Sincerely, 

Greg Abbott 

Governor 

cc: Senator John Comyn 

Senator Ted Cruz 

Congressman Will Hurd 

Congressman Beto O'Rourke 

Congressman Joaquin Castro 

Congressman Henry Cuellar 

Congressman Lloyd Doggett 

Congressman Lamar Smith 

Congressman Mike Conaway 

Congressman Roger Williams 

Anne ldsal, EPA Administrator for Region 6 

Bryan W. Shaw, Chairman ofTCEQ 

Richard Hyde, Executive Director ofTCEQ 

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DOCUMENTS SUBMITTED BY REPRESENTATIVE SUZANNE BONAMICI

June 21, 2018 

U.S. House Committee on Science, Space, & Technology 

Subcommittee on Environment 

AMERICAN 

LUNG 

ASSOCIATION 

Dear Chairman Biggs, Ranking Member Bonamid, and members of the Subcommittee on 

Environment of the House Committee on Science, Space, & Technology: 

The undersigned public health, medical and nursing organizations strongly support the full 

implementation and enforcement of the Clean Air Act's protections from ozone pollution, 

including the 2015 standard. Ensuring the cleanup of ozone pollution is critical to protecting 

public health. 

In 2015, our organizations strongly urged the U.S. Environmental Protection Agency (EPA) to 

update the National Ambient Air Quality Standard (NAAQS) for ozone to a level that protected 

human health, including for children, people with lung disease, and others who are at greater risk 

of health harms. The finalization of the 2015 ozone standard was an important step toward 

ensuring healthy air, with projected benefits of 230,000 childhood asthma attacks and 160,000 

missed days of school prevented every year by 2025. 

These benefits will not be realized without full implementation and enforcement. Our 

organizations are committed to ensuring that EPA work with communities in nonattainment for 

the 2015 ozone standards to make real pollution reductions, including with strong New Source 

Review requirements and without excessive exemptions of unhealthy ozone days. 

The Clean Air Act requires that the NAAQS be set at the level necessary to protect human health, 

including for vulnerable populations, with an adequate margin of safety. In a unanimous decision 

in 2001, the U.S. Supreme Court underlined that the sole basis for setting the standard was the 

protection of public health. However, in a May 2018 memo, EPA Administrator Scott Pruitt called 

for the incorporation of other considerations that are clearly not applicable under the Supreme 

Court decision, such as potential economic and energy impacts, into the standard-setting process. 
145 

These considerations are not consistent with the statutory requirements in the Clean Air Act and 

could lead to standards that are not requiste to protect public health with an adequate margin of 

safety. 

The memo further called for background ozone levels to be taken into account in setting the 

standard itself, an unnecessary request since the levels of background ozone have been discussed 

throughly in the last two reviews of the standard. These reviews examine ozone from all sources, 

as the human body needs protection from ozone regardless of the source. 

Future ozone and other NAAQS must continue to be based solely on what the health science 

shows is necessary to protect human health. The law already allows economic considerations to 

be taken into account when the standard is being implemented, but they have no bearing on the 

scientific question of how much ozone is safe to breathe. Even background ozone is already 

addressed in implementation; days when background ozone is excessive can be treated as 

exceptional events that do not affect meeting the standard. 

Our organizations oppose the changes proposed under EPA's memo, coupled with the agency's 

proposal to restrict the science it considers in its decisionmaking to exclude seminal health 

studies. Those changes will likely result in inadequate health protections from ozone pollution and 

other pollutants. EPA must follow the law and fully implement and enforce the 2015 ozone 

standards, and set any future standards based solely on what the best health science· shows is 

necessary to protect the health of the communities we serve. We call upon this subcommittee to 

oppose any changes to these policies and procedures at EPA that would put public health at risk 

by blocking, weakening or delaying the cleanup of ozone pollution. 

Sincerely, 

Allergy & Asthma Network 

Alliance of Nurses for Healthy Environments 

American Academy of Pediatrics 

American Lung Association 

American Public Health Association 

Children's Environmental Health Network 

Health Care Without Harm 

National Association of County and City Health Officials 

Trust for America's Health 
146 

To American Lung Association 

FROM Andrew Baumann and Maura Farrell, Global Strategy Group 

DATE April 23, 2018 

RE POLL RESULTS: Voters Overwhelmingly Support Stricter Limits on Smog 

Last month, the American lung Association released a memo indicating voters' wide opposition to any efforts 

to weaken the stronger fuel efficiency standards put in place by the previous administration. As noted in the 

previous memo, our research also indicated that voters overwhelmingly support the Environmental 

Protection Agency (EPA) enforcing stricter limits on air pollution. 

When asked specifically about their support for enforcing the EPA's 2015 updated standards which placed 

stricter limits on the amount of smog that power plants, oil refineries, and other industrial facilities release, 

voters across party and demographic lines overwhelmingly support enforcing the 2015 standards. This 

support also holds up against scrutiny: when voters hear a balanced simulated debate, including strong 

arguments attacking the proposed new smog standards that reflect the language being used by their 

opponents, two thirds of voters continue to support enforcing these standards. 

Key findings from Global Strategy Group's recent nationwide poll of registered voters are as follows: 

KEY FINDINGS 

Voters' overwhelmingly support clean air laws and clean air 

enforcement agencies. Voters nationwide are broadly favorable 

towards the Clean Air Act (65% favorable/10% unfavorable) and 

the EPA (59% favorable/26% unfavorable). Voters also support the 

EPA's efforts to enforce stricter limits on air pollution more broadly 

by a margin of almost four to one (74% support/19% oppose, 

including 48% who strongly support). 

In keeping with voters' strong support for clean air policies, 

voters also intensely support the Environmental Protection 

Agency enforcing stricter limits on smog. A broad majority of 

voters (75%) support the idea of the Environmental Protection 

Agency enforcing its updated stricter limits on smog. Notably, a 

majority (56%) of voters strongly support the enforcement of the 

EPA's stricter limits on smog. less than a fifth of voters (18%) 

oppose the stricter limits. 

Support for stricter limits on smog outweighs opposition among 

Democrats, Republicans, and independent voters alike. Nearly all 

Democrats support enforcing the stricter limits (94% support/4% 

oppose), independent voters support enforcing the limits by more 

than five-to-one (77% support/15% oppose), and more 

Support for the EPA Enforcing 

Strocter lim1ts on Smog 

Support Oppose 

75% 18% TOTAL 

68 25 Men 

81 12 women 

82 11 18-44 

71 22 45-64 

6'8 23 65+ 

72 20 White 

85 12 Non-white 

49 39 Republican 

77 15 Independent 

94 4 Democrat 

76 20 Non·ctilh!ge 

75 16 College 

72 17 Northeast 

72 21 Midwest 

75 18 South 

82 16 West 

66 22 Patents 
147 

Republicans support (49%) than oppose (39%) enforcing the limits. Support for enforcing the 2015 limits is 

wide across the board and transcends the various demographic and regional groupings in the survey, 

including gender, age, education, and race. 

Support remains high even after voters hear arguments from both sides, including an argument from 

opponents of stricter smog standards that stresses the potentially negative economic and workforcerelated ramifications of enforcing stronger smog standards. Support for the EPA enforcing stricter smog 

limits starts out extremely high (75% support) and remains very robust following statements from both sides 

(66% support). After the debate, not only do two-thirds of voters express support, nearly half of voters 

express strong support for enforcing these stricter standards. 

Support for Enforcing EPA's Stricter Limits on S~og 

As you may know, in 2015, the Environmental Protection Agency updated air pollution standards to place stricter limits on the 

amount of smog that power plants, oil refineries, and other industrial facilities can release. Now, the EPA is tonsidering if it will enforce these stricter limits on smog. Do you support or oppose the Environmental Protection Agency enforcing these 

stricter limits on smog? 

Initial 

Some people say 

updated standards 

(;f thou~ 

every year by hofdlng poUuters acc-ountable for 

actions. If the EPA fails to enforce these standards, they would 

.be giving power plants a free pass to pollute and threaten the 

health of our children. 

Initial 

Total 

Global Strategy Group conducted a telephone survey from March 13th to 15th, 2018 among 800 registered 

voters nationwide. The margin of error is +/- 3.5% at the 95% confidence level and the margin of error for 

subgroups is greater. 
148 

DOCUMENTS SUBMITTED BY REPRESENTATIVE DONALD S. BEYER JR. 

Otnngress nf t}Je 'lniteil ~fates 

malilfington, il<!i: 2DS15 

The Honorable Scott Pruitt 

Administrator 

U.S. Environmental Protection Agency 

1200 PeMsylvania Avenue, N. W. 

Washington, D.C. 20460 

Dear Administrator Pruitt: 

April25, 2018 

We are concerned regarding the health and environmental consequences of a January 25, 2018, 

Environmental Protection Agency (EPA) memo, which dramatically weakens protections against 

toxic air pollution by withdrawing the long standing "once in, always in" (OIAI) policy. 

As you know, the Clean Air Act requires EPA to limit emissions of hazardous air pollutants 

(HAPs), including many known to cause cancer, harm development in children, and kill. The 

lengthy list includes mercury, arsenic, formaldehyde, benzene, asbestos, chlorine, cyanide, and 

lead. 

In the Clean Air Act amendments of 1990, Congress made major changes to the way EPA 

regulates these toxic emissions because the agency had regulated only seven HAPs in the 

preceding 20 years. Congress acted out of deep concern that Americans were dying of cancer 

and facing other serious adverse health effects as a result of exposure to industrial HAPs. 

Congress was quite prescriptive in its direction to the agency: we required EPA to issue rules 

limiting emissions of 189 toxic HAPs, from all categories of"major sources" of these pollutants. 

The law requires the "maximum degree of reduction in [HAP] emissions ... including a 

prohibition on such emissions, where achievable." Sources must employ "maximum achievable 

control technology" or "MACT" to reduce HAP emissions to levels that the top-performing 

sources in an industry sector already meet. Congressional concern with these carcinogens and 

neurotoxins was so great that the law also contains additional safeguards: periodic reviews for 

control technology updates; residual cancer risk authorities; strict compliance directives; and 

anti-backsliding provisions. 

From 1995 until this year, sources emitting HAPs were required to meet MACT standards if, on 

the date that the MACT standard went into effect, they had the potential to emit 1 0 tons of any 

one HAP or 25 tons of any combination of HAPs, aMually ("1 0/25 ton per year threshold"). To 

ensure major sources kept those protections in place, EPA implemented what became known as 

the "once in, always in" policy, requiring major sources to continue to meet HAP emission limits 

based on MACT, even as they lowered and maintained emissions at or below MACT limits. 

EPA recognized that, without this policy, polluting sources could curtail use ofMACT and 

increase their HAP emissions substantially above MACT-based emission limits, all the way up to 

the 1 0/25 ton per year threshold. 

On January 25, without providing any notice to the public or opportunity for comment on its 

step, EPA reversed this decades-old understanding. In a four-page memorandum, EPA 

PRJNTED ON RECYCLED PAPER 
149 

The Honorable Scott Pruitt 

April23, 2018 

Page2 

announced that sources currently complying with MACT air toxics standards now have the 

option of getting out of all MACT requirements if their emissions are below the I 0/25 ton per 

year threshold. EPA will permit this even if sources are currently subject to one or more MACT 

standards that reduces HAPs emissions well below that threshold, and even if that means sources 

may increase their hazardous emissions significantly and increase the health hazards to 

Americans in neighboring communities. 

This is not the first time EPA has tried to weaken protections against toxic air pollution so 

radically. When EPA proposed to take this same step more than 10 years ago, the agency's own 

regional offices expressed concern that the proposal would allow HAPs to increase, and "would 

be detrimental to the environment and undermine the intent of the MACT program."' The 

regional offices further argued that many plants would take the opportunity to use the less 

stringent requirements, and "the cost of the increased [HAP] emissions would be borne by the 

communities surrounding the sources."2 An EPA political appointee claimed at the time that 

industry would be motivated to be good neighbors and not increase emissions. However, after 

Congress inquired pointedly, this claim was revealed this to be little more than speculation, with 

no basis in fact.3 Thanks to the concerns raised during the open and transparent rulemaking 

process, EPA did not make the mistake of finalizing a proposal that would have jeopardized the 

health and welfare of the American public. 

Now, the current EPA has decided to re-litigate the past, purporting to authorize through mere 

guidance the approach of the failed 2007 proposed rule, and granting immediate permission to 

industries to increase HAPs substantially. What's more, we now have a snapshot of the potential 

toxic impacts this policy would have on communities near, and downwind from, the thousands of 

major sources subject to MACT. 

Last month. the Environmental Integrity Project released a brief analysis of the current HAP 

emissions of 12 major sources in the Midwest, and their potential emission increases without 

longstanding protections from HAPs. Combined, these facilities released over 121,000 pounds 

of HAPs annually in 2016, including neurotoxins like lead and carcinogens like benzene. 

Without the safeguards preserved in EPA's 1995 policy, the report found that "the total 

emissions from these major sources could more than quadruple to a total of 540,000 pounds a 

year, because the new exemption allows such facilities to save money by cutting back on their 

pollution controls."" Furthermore, the report highlighted the danger in relying on corporations to 

report their emissions to prove their HAP emissions are below the I 0/25 ton per year threshold 

1 Memorandum to EPA Offite of Air Quality Planning and Standards from EPA Regional Offices. Regional 

Cammen/s on Draft DIAl Policy Revisions, at 3 (Dec:. 13, 2005). 2 Memorandum to EPA Office of Air Quality Planning and Standards from EPA Regional Offices, Regional 

Comments on Draft DIAl Policy Revisions, at 3-4 (Det. 13, 2005). 

'Lener from Chairman John D. Oingell, Committee on Energy and Commerce, to William Wehrum, Acting 

Assistant Administrator, EPA Office of Air and Radiation (Feb. 23, 2007); Response Lener from William Wehrum, 

Atting Assistant Administrator, EPA Office of Air and Radiation, to Chairman John D. Dingell, Committee on 

Energy and Commerce (Mar. 30, 2007). 

• Environmental Integrity Project, Toxic Shell Game: EPA Reversal Opens Door 10 More Ha::ardous Air Pollution 

(Mar. 26, 20 18) (www.environmentalintegrity.org/wp-tontent/uploads120 17!02rroxic-Shei!.Qame.pdl). 
150 

The Honorable Scott Pruitt 

April23, 2018 

PageJ 

and will remain there. The report noted major sources "seldom actually measure their hazardous 

emissions" on their own volition, so monitoring requirements were created in scores of MACT 

standards to keep them honest. But EPA's reversal of an essential protection against toxic air 

pollution would allow industrial emitters to no longer meet the monitoring, recordkeeping, or 

reporting requirements in MACT standards. This is in addition to letting polluting facilities 

evade the emission limits that protect Americans from increased HAPs.5 

The Environmental Defense Fund released a second report assessing the toxic air pollution 

impacts on the Houston-Galveston region from EPA's new loophole, focusing on at least 18 

potentially eligible facilities. 6 The report found that if all these facilities took advantage of the 

loophole to the maximum extent allowed by EPA's January rollback, the "total annual emissions 

of hazardous air pollutants from these facilities would increase by almost 146 percent over 2014 

levels, to a total of900,000 pounds."' Moreover, the report identified eight more facilities that 

appear eligible for the loophole; adding these facilities would increase emissions by 400,000 

more pounds. EPA's new loophole would allow a total increase of an astonishing 1.3 million 

pounds of HAPs from just these 26 industrial facilities in the Houston-Galveston region.8 

We share the serious concerns of those who opposed past attempts to undermine legal 

protections against HAP increases. The Environmental Integrity Project and Environmental 

Defense Fund analyses make our concerns far more pressing. This alarming information 

demands your immediate attention. 

The American public needs and deserves clean air and protection from hazardous air pollution. 

This is a matter of critical human health and safety. We ask you to reverse your decision to 

rescind the "once in, always in" policy, in order to safeguard future generations from harmful air 

pollutants. Thank you in advance for considering this timely and important request. 

Sincerely, 

~t£N'd0 DEBBIE 

Member of 

DINGELL 

Congress 

~ 

'Environmental Integrity Project, Toxic Shell Game: EPA Reversal Opens Daar ta Mare Ha::ardous Air Pollution 

(Mar. 26, 20 18) (www.environmentalintegrity.org/wp-content/uploads/20 17102ffoxic-Sheli..Qame.pdf). 6 Environmental Defense Fund, Pruitt's New Air To:tics Loophole: An Assessment of Potential Air Pollution 

Impacts in the Houston-Galveston Region(Apr. 10, 2018) (www.edf.org/sitesldefaulr/files!documeniS!OlAI· 

Houston%20case%20study%20FINAL.pdf). 

7 /d.,at2. 

•!d. 
151 

The Honorable Scott Pruitt 

April 23, 2018 

Page4 

11~~Jr..~~ Member of Congress 

~~~~ ELEANOR HOLMES NORTON 

Member of Congress 

!t/tJttv~ CM(ff . MATT CARTWRIGHT 

Member of Congress 

Member of Congress 

~b~ PAUL D. TONKO 

Member of Congress 

•161 MIKEQ GL 

Member of Congress 

~ Member of Congress 

~~ ~.VELAZQUEZ:' 

Member of Congress 

~u:tt lANA DeGETTE 

Member of Congress 
152 

The Honorable Scott Pruitt 

April23, 2018 

Page 5 

fjJ)I~ 

BILL FOSTER 

Member of Congress 

~KAc;t'~ Member of Congress 

~ DANIEL W. LIP~ p 

Member of Congress 

Member of Congress 

Member 

Mt~~ of Congress 

FREDERICA S. WILSON 

Member of Congress 

GREGORIO KILitJ CAMACHO SABLAN 

Member of Congress 
153 

The Honorable Scott Pruitt 

April23, 2018 

Page6 

DORIS 

~-~~ MATSUI 

Member of Congress 

~~ ~MICI 

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A. DONALD McEACHIN 

Member of Congress 

DAMS ITH 

Member of Congress 

g,o~ Member of Congress 

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Member of Congress 

~ 

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KEITH ELLISON 

Member of Congress 
154 

The Honorable Scott Pruitt 

April23,2018 

Page7 

l~b.----- DWIG TEVANS 

Member of Congress 

Member of Congress 

MICHAEL E. CAPU 

Mefber of Congress 

(I 

~~~~~~ BONNIE WATSON COLEMAN 

Member of Congress 

Member of Congress 

"'EARLBLU ~~-- ENAiJER 

Member of Congress 

Member of Congress 

Member of Congress 

Member of Congress 
155 

The Honorable Scott Pruitt 

April24, 2018 

PageS 

PETER WELCH 

Member of Congress 

TEDW.LIEU 

Member of Congress 

Member of Congress 

Member of Congress 

La.f1a4 

SUSAN A. DAVIS 

Member of Congress 

Y£~ RICK LARSEN 

Member of Congress 

BRENDA L. LAWRENCE 

ADRIANO ESPAll..LAT 

Member of Conn. 

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Member of Congress 

~ sHI<::s ~\k'­ . Member of Congress 
156 

The Honorable Scott Pruitt 

April25, 2018 

Page9 

~· Member of Congress 

~~~ LINDA T. S CHEZ 

Member of Congress 

s~?~y(t BRENDAN F. BOYLE 

Member of Congress 

l'oJJ. .5\ ..... ~cA:QJ... 'e"AROL SHEA-PORTER 

Member of Congress 

Member of Congress 

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Member of 

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Congress 

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~l.)( - ~.a< . MARK DeSAULNIER 

Member of Congress 
157 

The Honorable Scott Pruitt 

Apri125, 2018 

Page 10 
158 

<ftnugress nf tlfe Nuiteb j;tutes 

maslpingtnn, il<lr 20515 

The Honorable E. Scott Pruitt 

Administrator 

U.S. Environmental Protection Agency 

1200 Pennsylvania Avenue, N.W. 

Washington, D.C. 20460 

Dear Administrator Pruitt: 

June 14,2018 

We are deeply concerned with your May 9th memorandum regarding future National Ambient 

Air Quality Standards (NAAQS) reviews and standard setting. 

Section 1 09(b )(I) of the Clean Air Act directs EPA to establish "ambient air quality standards 

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." 

Health is the sole criterion for setting the primary standard. Yet your memo invites that criterion 

to include economic costs. 

Your memo specifically asks the Clean Air Scientific Advisory Committee (CASAC) to consider 

"adverse social, economic, or energy effects related to NAAQS" during the standard-setting 

process. Currently, cost considerations inform implementation of the health standards, but not 

their establishment. The Supreme Court unanimously confirmed this point in Whitman v. 

American Tntcking Associations, 531 U.S. 457 (2001 ), ruling that EPA may not consider 

implementation costs in setting NAAQS. 

The health-based NAAQS have driven lifesaving air pollution cleanup for decades. According to 

EPA's own analysis, from 1970 to 2015, aggregate national emissions of the six criteria 

pollutants dropped an average of70 percent- even as GOP grew by 246 percent. The agency 

also found that steps taken under the Clean Air Act, including implementing and enforcing the 

NAAQS, will prevent 230,000 premature deaths in the year 2020 alone. The work of the Clean 

Air Act and the NAAQS is far from finished, as more than four in ten Americans still live in 

areas where levels of ozone or particle pollution make the air unhealthy to 

breathe. 

Allowing the consideration of factors other than health in setting future NAAQS would not only 

result in inadequate standards that would cause undue harm to the health of millions of 

Americans, it would also set a dangerous precedent for setting EPA standards. Your memo calls 

for the expedited review of two pollutants, particulate matter and ozone, which have the potential 

to aggravate asthma, increase the severity of chronic lung diseases, damage the lungs, cause 

cardiovascular harm, and even cause death. Emerging research shows links to additional health 

harms. Those at increased risk include children, seniors, pregnant women, people with chronic 

lung and heart disease, people who work or exercise outdoors, people of color, and lower-income 

communities. Weakening these public health and clean air standards to help industry will not 

PAINTEC ON RECYC\.EO PAPER 
159 

eliminate costs, it will merely shift them to communities, workers, and children, and increase the 

cost of medical care for those affected. 

Using the CASAC as the vehicle to make this change is also very concerning given your decision 

to bar scientists that receive agency funding from acting on advisory boards. This action 

diminishes the input from the world's best scientists and we fear it will advantage the economic 

arguments of industry to the detriment of public health. It is clear from the Clean Air Act's text, 

"allowing an adequate margin of safety," that the intent of Congress is to err on the side of 

caution to protect human and environmental health. Any leniency to ozone and particulate matter 

NAAQS as a favor to industry resulting from these reviews will only endanger health and the 

intent of the Act. 

There is a highly problematic, internal contradiction at the heart of your memorandum and your 

charge to CAS A C. In describing the controlling legal precedent, your memo claims that "adverse 

public health ... effects" from attaining a standard are "relevant to the standard-setting process." 

The memo then uses ellipses to omit that the other impacts related to implementation of the 

standard, may be considered only after that standard has been set: namely economic impacts, 

energy effects, etc. that may result from various attainment strategies. Despite this, your memo's 

'charge questions' to CASAC asks them to "advise the Administrator of any adverse public 

health, welfare, social, economic, or energy effects which may result from various strategies for 

attainment and maintenance of such NAAQS" during the standard-setting process. This charge 

question to CASAC contradicts the memo's recognition of the restrictions in the controlling 

Supreme Court decision. The memo notes that your charge may "elicit information which is not 

relevant to the standard-setting process, but provides important policy context for the public, coregulators, and EPA." CASAC must only consider adverse public health effects--from the air 

pollutant itself-that are relevant to the standard-setting process, during that process. CASAC 

should not consider alleged health effects related to attainment strategies, and CASAC certainly 

must not consider economic or energy effects allegedly resulting from those implementation 

strategies, during any health standard-setting process. 

Your memo's stratagem-formally directing CASAC to consider non-health factors during the 

standard-setting process, before final standards are adopted-is highly objectionable. We, 

therefore, urge you to withdraw the improper charge to CASAC at once, and to make clear that 

CASAC-and EPA-will remain focused exclusively on the adverse public health effects that 

the Clean Air Act and a unanimous Supreme Court confirm are the only relevant statutory 

considerations during the health standard-setting processes. 

The Clean Air Act has been an overwhelming success for the health of Americans. We urge you 

not to backslide on that legacy. 

~~f4 Member of ongress 
160 

ilaJayap 

Member of Congress 

iJ41H_[J....,...__,J'# 

Debbie Wasserman Schultz 

~l:L ber of Congress 

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Member of Congress 

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Member of Congress 

CbC{i;1.Ut Jb e te mgree 

Member of Congress 

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Adriano Espaillat 

Member of Congress 

Alan 

~~ Lowenthal 

Member of Congress 

~;J/Zy- Member of Congress 
161 

Member of Congress 

Debbie 

~~~ Dingell (J 

Mem Congress 

Member of Congress /£:::~ 

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Member of Congress 

Bill Foster 

Member of Congress 

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Member of Congress 

o)y')t\ G. E.-sho-oAnna G. Eshoo 

Member of Congress 

_)J/~)).~ Paul D. Tonko 

Member of Congress 
162 

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Member of Congress 

wen Moore 

Member of Congress 

~tt~~ Doris Matsui 

Member of Congress 

tw~,...~~~Y~:.._~__::=~< . Mark DeSaulnier 

Member of Congress 

Eleanor Holmes Norton 

Member of Congress 

Member of Congress 

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Donald M. Payne, Jr. 

Member of Congress 

M~ Member of Congress 

Betty 

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Mem of Congress 

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Member of Congress 

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163 

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Member of Congress 

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Darren Soto 

Member of Congress 

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Member of Congress 

~~~.s=t;- TedW. Lieu 

Member of Congress