How’s EPA Doing on Air Pollution Science?

October 26, 2022 | 2:00 pm
Smokestack air pollutionDocumerica/Unsplash
Anita Desikan
Senior Analyst

Recently, the National Academies of Sciences, Engineering, and Medicine released a report that will likely have major effects on how the Environmental Protection Agency (EPA) protects people from dangerous air pollutants.

At issue is the EPA’s process of compiling what the agency calls an “integrated science assessment.” The focus might sound esoteric, but the stakes could not be higher, especially given the fact that a large and growing body of evidence links air pollution to death and illness, particularly cardiovascular disease, cancer, and respiratory problems. For instance, particulate matter air pollution is one of the leading causes of death around the world and it can potentially affect or damage every organ in the body.

Understanding the EPA’s integrated science assessment

When Congress passed the Clean Air Act in 1970, they determined that six so-called “criteria air pollutants”—particulate matter, ground-level ozone, carbon monoxide, lead, sulfur dioxide, and nitrogen dioxide—were so dangerous they required a rigorous and regularly updated process of assessment and policymaking. The law requires that the EPA carry out a study, called an “integrated science assessment,” that combs through the scientific literature and articulates exactly how dangerous these pollutants are to people’s health and the environment. The EPA’s integrated science assessment forms the scientific backbone of the national ambient air quality standards, the set of standards that determines how the federal government protects communities across the United States from these harmful air pollutants.

There’s little question that the EPA needs the strongest possible science-based process to do its job of safeguarding the public from air pollution. The report by the National Academies of Science—one of the nation’s most well-respected institutions of scientific expertise—is, in essence, the scientific equivalent of a report card that can help the EPA make its integrated science assessment process even more robust.

The National Academies report is largely positive about the EPA’s weight-of-evidence approach for determining causality (that is, determining if a particular air pollutant causes harm to health and welfare). This finding itself is important for validating that the EPA’s approach is scientifically rigorous.

But the National Academies also makes several recommendations about where the EPA can improve its methods, including how best to assess harms that are occurring in populations that are more vulnerable to the detrimental effects of air pollutants. The EPA would be wise to listen to these recommendations because doing so will translate to policy decisions that can better protect human health and the environment.

Centering “sensitive” populations

The first recommendation in the National Academies report presses the EPA to more fully assess the impacts of air pollutants on populations (human and other biological organisms) that are especially susceptible to their effects. In this recommendation, the National Academies also notably includes impacts to at-risk ecosystems which can help highlight impacts on endangered and threatened species and other sensitive or critical habitats especially vulnerable to air pollution.

For the six criteria air pollutants, the Clean Air Act charges the EPA to provide health protections to all human populations, including “sensitive” populations such as asthmatics, children, and the elderly. Recently, the EPA has been trying to prioritize an examination of the health and welfare effects on sensitive populations, as can be seen by the EPA’s 2021 supplemental integrated science assessment on particulate matter air pollution. However, the agency has separated this examination from its efforts to determine causality. This is concerning since causality determinations of a health or welfare effect essentially form the basis of whether the EPA will set looser or more stringent standards for a particular criteria air pollutant.

As the report highlights, numerous scientific organizations (including UCS) over the years have pointed out that the EPA also needs to give greater attention to marginalized communities—such as communities of color, low-income communities, children, and the elderly, and people with pre-existing health conditions—that are at-risk of developing more frequent and severe health impacts from exposure to air pollution.

The problem is that the current way the EPA assesses air pollution science tends to overlook health effects that are occurring more often in marginalized communities. For instance, the National Academies report highlights an instance where a very large study on healthy human adults—which was conducted at multiple sites and appeared to find less evidence of health effects due to ozone pollution—appeared to drown out smaller studies that showed strong evidence that people with cardiovascular conditions, or at-risk of cardiovascular conditions, were susceptible to health effects due to ozone pollution. Additionally, many studies of human exposure to air pollutants have tended to exclude people with serious health conditions and often do not have good representation of people or color and low-income individuals.

The National Academies report finds that unless the EPA has specific methods in place to assess whether at-risk populations are experiencing health symptoms caused by the air pollutant being examined, its current methodology will place a greater weight on health risks to the overall, average population rather than health risks occurring in marginalized populations. If the EPA is serious about its commitment to environmental justice, it needs to follow this recommendation and fully implement an examination of at-risk population when assessing causality.

More transparency needed

The National Academies report also points out that more transparency is needed in EPA’s methodology, such as by: providing details on how the agency chooses the studies it decides to include (and not include) in its integrated science assessments; considering more types of confounding variables that can influence study results, such as weather effects and socioeconomic and demographic differences; and articulating a clear process for identifying which scientific disciplines and perspectives will be needed when making a causal determination.

As we learned under the Trump administration, this process can become sidelined when political leaders work to disband and/or undermine the scientific advisory committees and EPA scientists who help assess the scientific literature on the health and welfare dangers of air pollutants. Therefore, it is vital for the EPA to implement the National Academies of Sciences’ recommendations as this transparency can enhance public trust in the EPA’s process and thwart attempts by current and future political leaders who might want to meddle in the process.

The EPA needs to assure the public that it is committed to using an equitable and rigorous science-based process to protect all people in the United States, particularly marginalized communities, from the enormous health burdens that can result from exposure to air pollution.