UPHE’s comments to the EPA on proposed updated National Ambient Air Quality Standards

March 28, 2023

Utah Physicians for a Healthy Environment (UPHE) is one of the largest civic organizations of healthcare professionals in the Western US, including about 450 physicians, some of whom are academics and researchers, but most of whom are clinicians, and 3,500 members of the lay public. We practice on the front lines of public health, 24/7, 365 days per year. Our patient care responsibilities provide us with a different perspective on pollution’s health consequences from what EPA might get from other environmental groups or non-clinicians doing only research. We submit these comments for the purpose of demonstrating that EPA’s proposed changes to the PM2.5 National Ambient Air Quality Standards (NAAQS) are inadequate to protect public health, do not reflect an overwhelming body of relevant science (most of which EPA already has at hand), and do not satisfy EPA’s legal obligations to do both. We urge the EPA to adopt a 24hour standard of 20μg/m3 and an annual standard of 8 μg/m3 for PM2.5.

Executive Summary

A. Introduction

B. Trends suggest air pollution will be an even larger health burden to the US population in the future.

1. The US population is aging.

2. The urban migration increases air pollution exposures.

3. The climate crisis is increasing multiple types of pollution.

4. Like previous research trends, future research is likely to show greater health impacts and show them with more accuracy.

5. Airborne plastic nanoparticles are adding to toxicity of particulate pollution (PM).

6. Incidence of cancer in young people is increasing. They will need more protection from PM.

7. PM increases morbidity and mortality from COVID, a disease likely to become endemic.

8. Life expectancy is dropping, and air pollution is connected to several contributing trends.

C. EPA’s methodology is flawed.

1. The EPA standard for declaring causality is extreme.

2. Medical organizations have long called for stricter standards than the EPA eventually adopts; this proposal is an example of this disparity.

3. The form used to establish the 24-hour standard must be changed to 99th percentile.

4. The standard for nitric oxide and nitrogen dioxide (NOx, the nitrogen oxides most relevant for air pollution) has been virtually ignored; updating the PM2.5 standard will have ripple effect on NOx.

D. Clean Air Act (CAA) mandates that EPA establish stricter standards.

1. “Adequate margin of safety” is required, including for the public to engage in outdoor activities.

2. The EPA may not consider cost or feasibility.

3. The precautionary principle applies: the EPA must protect the public from “known” hazards and those about which there is still scientific uncertainty.

4. Setting standards is an expression of a value system, not just of science.

E. EPA Looks at the right science but draws the wrong conclusions.

1. Some EPA conclusions are wrong on their face and even defy common sense.

2. EPA methodology is arbitrary and eliminates too many valuable studies.

a. There is no reason to eliminate studies outside of North America.
b. Insisting on a common “ambient exposure” standard eliminates outliers such as Utah.
c. Over emphasizing co-pollutant confounding is counterproductive to protecting public health.
d. EPA seems to ignore critical autopsy studies.
e. EPA is inconsistent in their consideration of heterogeneity of studies.
f. EPA should act as caregivers must, with less than perfect knowledge.
g. EPA inappropriately discounts morbidity studies.
h. EPA gives inappropriate weight to controlled human exposure studies.
i. EPA is wrong to discount biochemical and histological studies and studies of subtle clinical outcomes.
j. The Clean Air Scientific Advisory Committee (CASAC) is correct that EPA is wrong to over emphasize the use of the “mean” in exposure studies.
k. CASAC is right in criticizing EPA for excluding areas impacted by wildfires and winter inversions.

3. We agree with CASAC that lowering the annual standard alone will leave many communities and subgroups without protection from short-term pollution hazards.

4. By relying on PM2.5 mass measurements, EPA is likely underestimating the toxicity of PM.

5. EPA’s standard for declaring causality is arbitrary and extreme.

F. A small fraction of the studies that compel stricter standards:

1. Supralinear dose/response relationship at low exposures.

2. PM2.5 and mortality:

a. Mortality and long-term exposure.
b. Mortality and short-term exposure.
c. Association with infant mortality.
d. Association with ICU and COVID mortality rates.

3. PM2.5 and the cardiovascular system:

a. PM2.5 is a key contributor to atherosclerosis, arteriole narrowing, plaque rupture, and cardiac ischemia.
b. Effect on heart electrophysiology.
c. Effect on blood pressure.
d. Association with pulmonary hypertension.
e. Association with heart failure (HF), morphologic changes, and blood clots.

4. PM2.5 and the brain and nervous system:

a. Interferes with brain development.
b. A significant contributor to stroke.
c. Impaired cognition.
d. Association with Parkinson’s Disease.
e. Association with dementia and Alzheimer’s Disease.
f. Association with multiple psychiatric and tic disorders.
g. Anatomic brain changes.

5. PM2.5 and reproductive toxicity, fetal development/chromosomal integrity:

a. Preconception toxicity impairs fertility, organogenesis.
b. Quantitative consequences of preconception exposure.
c. Prenatal exposure increases the risk of birth defects.
d. Prenatal exposure is associated with chromosomal damage and decreased telomere length.

6. PM2.5 and pregnancy and birth outcomes:

a. Impairs fetal growth.
b. Is associated with premature birth.
c. Other pregnancy, birth complications.

7. PM2.5 and the lung:

a. PM2.5 and parameters of lung function.
b. PM2.5 and COPD and asthma.
c. Association with respiratory infections.
d. PM2.5 and idiopathic pulmonary fibrosis.

8. PM2.5 and Cancer:

a. PM2.5 and increased risk of cancer.
b. Decreased rate of cancer survival.

9. PM2.5 and Metabolic, Endocrine, and Kidney Disease:

a. PM2.5 and risk of type II diabetes and glucose intolerance.
b. Obesity, metabolic syndrome, and thyroid dysfunction.
c. Chronic kidney disease.

10. PM2.5 and miscellaneous health impacts.

11. PM2.5 and environmental justice.

G. Economic considerations

1. The economic benefits of tightening the annual standard is overwhelmingly positive, nationally and in Utah Cost benefit analysis favors annual standard of 8 ug/m3 over 9-10.

2. Economic benefits to the heavily populated areas of Utah

H. Conclusion


On March 8, 2023, a worldwide news headline read, “Almost everyone in the world breathes unhealthy air.” The report referenced a study published in Lancet Planetary Health that showed that virtually everyone across the globe is exposed to air pollution that exceeds the standards proposed by the World Health Organization (WHO). The WHO states, “Air pollution is the greatest environmental threat to health and well-being at the global scale, and all populations are affected….” It is from that general assessment that WHO makes recommendations for much stricter standards than EPA. In the three documents that form the scientific basis of EPA’s proposed changes, 2019 Integrated Science Assessment for Particulate Matter, 2022 Supplement to the 2019 Integrated Science Assessment for Particulate Matter, and Preamble to the Integrated Science Assessments, we see no scientific justification for EPA to adopt the standards they are proposing.

Although a wealth of science is available to guide EPA’s decision, in the end, setting the NAAQS is a discretionary act. The decision will be one of judgement and values, not technical analyses of the quality of the data. For the last 16 years, UPHE has kept very close track of the world’s air pollution and health research. When we see that time and again, EPA, under both Republican and Democratic administrations, makes standards that we and most other medical organizations believe to be too weak, standards that don’t adequately reflect the science that we are familiar with, we feel obligated to speak out.

Our interaction with patients and their families compels us to see this issue not on the abstract level of morbidity and mortality statistics and causality probabilities, but on the level of the human faces behind those numbers and equations. We interact personally with air pollution’s victims and their families. They experience real diseases, real economic losses and disability, loss of quality of life, real suffering, and sometimes irreversible tragedy and death from air pollution.

What are the risks and benefits of EPA’s options in establishing PM2.5 NAAQS? EPA’s current proposal contradicts any reasonable risk/benefit analysis. If EPA sets NAAQS at 8 μg/m3 annual and 20 μg/m3 daily averages or lower, that would be unequivocally supported by current science, even if an argument can be made that the supportive science is still incomplete. If it turns out the science behind that decision was wrong or merely premature, and the end result was 330 million people breathed cleaner air than necessary or cleaner air than polluting industries were willing to acquiesce to in court, what is the societal cost? At the very most, a slim possibility of a reduction in some kinds of economic activity. However, EPA’s own cost analysis found that the benefits of pollution reductions afforded by EPA’s enforcing the Clean Air Act from 1990 to 2020 paid off at a rate of 30 to 1. Is it logical that a slightly overzealous NAAQS PM2.5 would have a reverse economic impact? The medical and economic literature certainly doesn’t support such a scenario.

From a public health standpoint, there is obviously no such thing as air that is too clean. There would also be a co-benefit of reducing CO2 emissions, and we could ask another absurd rhetorical question, “Is there such a thing as too much climate protection?”

On the other hand, if EPA sets NAAQS that are too weak, it also risks economic consequences from increased healthcare costs, decreased worker productivity, and lost employment, but it obviously also risks quality of life, increased morbidity, shortened life expectancy, and directly increased mortality.

To be simpler and more direct, EPA failed to do its job in allowing 11 years and 17 years, respectively, to elapse since the annual and 24-hour PM2.5 NAAQS were last updated. As with justice, “public health protection delayed is public health protection denied.” When the EPA errs on the side of NAAQS that are too weak or delays updating them, public health consequences on a massive scale are the result. Tens of thousands of lives are shortened or lost, millions are victimized with life-altering morbidities, and virtually every US resident suffers to some degree, even if, for some, it is subclinical and not quantifiable. Even worse, establishing regulations that indisputably allow this as an end result codifies a cynicism and disrespect for human life into federal agency regulatory actions that tend to be perpetuated and normalized. Much of the world looks to EPA for guidance on environmental and public health protection, so the consequences of weak or delayed regulations reverberate throughout the world, affecting billions of lives.