EPA Science Panel Considering Guidelines That Upend Basic Air Pollution Science

Mar 28, 2019
Originally published on March 29, 2019 10:18 pm

Several members of a powerful science panel for the Environmental Protection Agency expressed doubt at a hearing Thursday about the long-established scientific consensus that air pollution can cause premature death.

The panel was meeting to consider recommendations that would fundamentally change how the agency analyzes the public health dangers posed by air pollution and could lead to weaker regulation of soot.

The recommendations concern how the EPA regulates microscopic soot known as particulate matter, which causes and exacerbates respiratory diseases such as asthma. Determining exactly how much particulate matter is safe to breathe requires complex analysis of an enormous — and growing — body of scientific literature.

Before the EPA disbanded it last year, a 20-person subcommittee called the Particulate Matter Review Panel was responsible for helping the agency decide how much air pollution is safe for Americans to breathe. With that group gone, only the seven-member Clean Air Scientific Advisory Committee is left to make recommendations.

At a public meeting Thursday that ran nearly two hours long, multiple members of that committee, including Chair Tony Cox and Steven Packham of the Utah Division of Air Quality, said they do not agree that breathing air polluted with soot can lead to an early death.

"[Committee] members have varying opinions on the adequacy of the evidence supporting the EPA's conclusion that there is a causal relationship between [particulate matter] exposure and mortality," said Cox, reading from the committee's draft recommendations before explaining that he is "actually appalled" at the lack of scientific evidence connecting particulate pollution to premature death.

"This is waving a red flag in front of a bull, so I acknowledge that," Cox continued.

The draft recommendations would dramatically limit the breadth and depth of the science used to determine safe air pollution limits in the U.S. by pushing the EPA to limit the types of studies considered during the regulatory process.

The EPA currently bases its air pollution regulations on a wide range of scientific studies about the relationship between health outcomes, such as asthma or premature death, and different types of air pollution, such as soot of different microscopic sizes.

"The EPA has a very well-vetted process that has been going on over the years called the weight of the evidence," says Francesca Dominici, a biostatistician at the Harvard T.H. Chan School of Public Health who recently wrote about the draft recommendations in the journal Science. "This is a process that has been endorsed not only by the EPA, but by the National Academy of Sciences, [and] is pretty well accepted by the scientific community."

"Every time you try to assess the link between exposure to a contaminant and health," Dominici says, "you have to make sure there is consistency in the evidence across many, many studies, across many disciplines," including atmospheric chemistry, toxicology, epidemiology and exposure, and data science. That's important, she explains, because no one study captures everything about a given pollutant.

"You can't randomize millions of [people] around the world to breathe higher pollution or lower pollution, so we have to rely on observational data," Dominici says.

Decades of broad analysis have enabled scientists to make clear recommendations to the EPA about how to protect Americans from air pollution. "They're providing a very robust message that air pollution is harmful to human health," Dominici says.

But at Thursday's hearing, Cox and others expressed concern that the current system overstates the scientific certainty around air pollution.

"If we don't know that X causes Y, then we should say we don't know," said Cox, who consults and lectures about various risk-related topics. He expressed concern that the EPA would move to reduce air pollution under the erroneous assumption that it would result in fewer premature deaths.

To avoid that, Cox has shepherded through recommendation language that emphasizes uncertainty about the relationships between air pollution and respiratory disease.

If the EPA adopts those recommendations, many scientists warn it will lead the agency to underestimate the effects of air pollution on public health.

"I just want to emphasize the fringe nature of these proposals," says H. Christopher Frey, a former chair of the Clean Air Scientific Advisory Committee and member of the now-disbanded particulate matter review board.

"It's kind of like the same issues that came up with tobacco denial of health effects or denial of climate change health effects," Frey says. "There's a very small community that have scientific credentials but are moving outside their area of expertise to try to raise doubt after doubt after doubt on issues where they really don't have the strongest competence."

"There are other experts who are much stronger, much better informed, much more aware of the leading edge," he argues.

In a surprise development, the full panel appeared to agree that other experts should be brought in to review the current recommendations. Members are calling on the EPA either to reinstate the disbanded 20-person panel of particulate matter experts or to create a new expanded panel with even broader expertise to review the recommendations of the Clean Air Scientific Advisory Committee before they become final.

Copyright 2020 NPR. To see more, visit


Scientists have gathered plenty of evidence to show that breathing polluted air is bad for your health, but multiple members of an EPA science advisory panel say they are not entirely convinced. They are considering recommendations that could lead to looser regulations on soot. Here's NPR's Rebecca Hersher.

REBECCA HERSHER, BYLINE: The pollution in question is microscopic soot called particulate matter. It gets into the air from car exhaust and smoke, and it's small enough to lodge itself in the nooks and crannies of people's lungs. Francesca Dominici is a biostatistician at Harvard.

FRANCESCA DOMINICI: We know a lot. This issue has been studied now for over 30 years.

HERSHER: Those decades of research have shown that breathing soot makes people sick. It makes it more likely that you'll get respiratory diseases, cardiovascular diseases, that you'll end up in the hospital, that you'll die prematurely. And the way the EPA has determined that is by asking a panel of experts, mostly scientists, to analyze all the research that's out there.

DOMINICI: The EPA has a very well-vetted process that has been going on over the years called the weight of evidence. This is a process that has been endorsed not only by the EPA, but the National Academy of Science.

HERSHER: The system is deceivingly complex because the relationship between air pollution and health is actually hard to study. You can't just run a science experiment on people all over the world.

DOMINICI: You can't randomize millions of subjects around the world to breathe higher pollution and lower pollution. So we have to rely on observational data.

HERSHER: And observational data is messy. It doesn't just have information about pollution. It has all the other things that affect our health - age and weather and income and even our genes. It's hard to figure out what's causing what here, which has led a small minority of statisticians and other researchers to question the consensus that air pollution shortens our lives. And some of those researchers are on the EPA's Clean Air Scientific Advisory Committee. One of them is Tony Cox, the committee chair, who was appointed by the Trump administration. He led a public hearing on Thursday about new recommendations the committee is considering.

TONY COX: I look at all this literature. I'm really struck and actually appalled.

HERSHER: In Cox's opinion, there is little or no evidence linking particulate pollution to premature death. He knows it's not a popular one with the public and a lot of other scientists.

COX: This is waving a red flag front of the bull, so I acknowledge that.

HERSHER: Nonetheless, the panel has drafted new science recommendations that would dramatically shrink the number of scientific studies the EPA considers when it's deciding how much air pollution is safe to breathe. Christopher Frey used to have Cox's position as the committee chair.

CHRISTOPHER FREY: You know, if you were doing a story where you would give sort of equal weight to the viewpoints, you would interview him and then you would interview 60 people who don't share his view. And that would represent kind of what the reality is.

HERSHER: Frey was also a longtime member of a larger, 20-person group of experts specific to particulate matter pollution. The Trump administration dissolved that group out of the blue last fall. Frey says their expertise is missing from the smaller committee that's left.

FREY: There are other experts who are much stronger, much better informed, much more aware of the leading edge.

HERSHER: And in a bit of a twist, Cox and the other committee members appeared to agree. At Thursday's meeting, they decided to call on the EPA to reinstate a bigger, more-diverse group of experts who can help review the science as the EPA considers updating rules over the next year. Rebecca Hersher, NPR News. Transcript provided by NPR, Copyright NPR.