February 17, 2023

The United States Environmental Protection Agency (EPA) recently proposed revisions to strengthen the National Ambient Air Quality Standards (NAAQS) for fine particle pollution to better protect communities, including those most overburdened by pollution. They are currently accepting public comment on their proposal.

Dr. Barbara Turpin

Dr. Barbara Turpin

Barbara Turpin, PhD, professor and chair of environmental sciences and engineering at the UNC Gillings School of Global Public Health, served on the Particulate Matter (PM) Review Panel of the Clean Air Scientific Advisory Committee (CASAC), which provides external oversight on EPA’s process. The Clean Air Act requires EPA to make use of the latest science to review the adequacy of the NAAQS every five years.

Turpin has worked for nearly three decades in aerosol science, atmospheric chemistry and environmental engineering, where her research aims to improve our understanding of the link between air pollution emissions and exposures to protect human health and quality of life.

“In this review, EPA was able to take into consideration new research that more directly documents differences in PM2.5 exposures across race and that identifies subpopulations at increased risk given identical exposures,” Turpin explained. “Finally, new research provides additional confidence in PM2.5 effect estimates, even at low concentrations.”

When fine particles, also known as PM2.5 or soot, are inhaled, they carry risk of serious health impacts, including asthma, heart attacks and premature death. This pollution disproportionately affects vulnerable populations In the U.S., including children, older adults, those with heart or lung conditions, as well as communities of color and low-income communities. These particles may be emitted directly from sources like construction sites, unpaved roads, fields, smokestacks or fires. Particles may also form in the atmosphere as a result of chemistry involving gaseous emissions from power plants, industrial facilities and vehicles.

EPA’s proposal focuses on strengthening the primary (health-based) annual PM2.5 standard from a level of 12 micrograms per cubic meter to a level between 9 and 10 micrograms per cubic meter, which would address health inequities and result in significant public health benefits.

The Clean Air Act requires EPA to set two types of air quality standards: health-based standards, called primary standards, and standards to protect public welfare, called secondary standards. Based on the scientific evidence and technical information, EPA has set two primary standards for PM2.5, which work together to protect public health: the annual standard, which EPA is proposing to revise, and a 24-hour standard, which the Agency is proposing to retain.

EPA estimates that if finalized, a strengthened primary annual PM2.5 standard at a level of 9 micrograms per cubic meter, the lower end of the proposed range, would:

  • prevent up to 4,200 premature deaths per year;
  • prevent 270,000 lost workdays per year; and
  • result in as much as $43 billion in net health benefits in 2032.

“Air pollution and health is a major area of research at Gillings and has been for over 50 years,” she commented. “Faculty in Gillings’ Department of Environmental Sciences and Engineering (ESE) were among the first to build smog chambers and use those to study the atmospheric chemistry that makes PM2.5. ESE faculty also have made major contributions to the design and evolution of regulatory models that enable state regulators to identify effective strategies to reduce air pollution and attain compliance with the NAAQS. One of the reasons I wanted to join UNC is the ongoing exciting work in this area by Professors Jason Surratt, Will Vizuete and Jason West.”

EPA will work closely with state, local and Tribal air agencies to implement the revised primary annual PM2.5 standard when finalized.

EPA is also proposing to revise other aspects related to the PM standards – such as monitoring requirements and the Air Quality Index (AQI) – that will help states and Tribal Nations meet the revised standards while making significant strides toward protecting the health of all people, including at-risk populations.

In June 2021, EPA announced it would reconsider the previous administration’s December 2020 decision to retain the 2012 PM2.5 standards, because available scientific evidence and technical information indicated that the standards may not be adequate to protect public health and welfare. In developing today’s proposal, EPA considered the best available science and technical information and carefully evaluated the recommendations of the CASAC in developing the proposed rule.

After a period of public comment, the agency plans to issue final standards later this year.

More information on particulate matter.

More information on the NAAQS review process and other documents related to this reconsideration.

Contact the UNC Gillings School of Global Public Health communications team at sphcomm@unc.edu.

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