Deadly Air
As Dr. Coates and Dr. Balakrishnan noted, the revised ambient air standard is averaged over a year, and as such may not accurately capture periods where particulate matter concentrations are dangerously high, as occurs in many US states and Canadian provinces during wildfire season, or when one of the more than 200 remaining coal-fired power plants in the US release clouds of soot during daily operations or especially during periods of high electricity demand.
Some pollution sources are worse than others, as shown by a study published in the November 24, 2023, issue of Science. Health and environmental investigators reported that among Medicare beneficiaries, exposure to PM2.5 from sulfur dioxide released by coal burning for electricity generation was associated with a doubling in risk of death compared to PM2.5 exposure from all other sources.
Air pollution has also been identified as a key factor in the development of non–small cell lung cancer in nonsmokers, according to Charles Swanton, PhD, of the Francis Crick Institute, and chief clinician of Cancer Research UK, both in London, and his colleagues.
As Dr. Swanton reported at the 2022 European Society for Medical Oncology Congress, among 447,932 participants in the UK Biobank, increasing exposure to PM2.5 was significantly associated with seven cancer types, including lung cancer. They also saw an association between PM2.5 exposure levels and EGFR-mutated lung cancer incidence in the United Kingdom, South Korea, and Taiwan.
And as the investigators showed in mouse models, exposure to PM2.5 of lung cells bearing somatic EGFR and KRAS mutations causes recruitment of macrophages that in turn secrete interleukin-1B, resulting in a transdifferentiation of EGFR-mutated cells into a cancer stem cell state, and tumor formation.
Monitoring At-Risk Communities
Lisa Frank, executive director of the Washington legislative office of Environment America, explained in an interview how the revised standards may result in improvements in air quality, especially for at-risk populations such as lower-income urban dwellers.
“Regulations on particulate matter have been around for a few decades now, so there’s an established process that the state agencies and the EPA go through to make sure that air quality standards are met,” she said.
Over the next several years, the EPA will designate areas of the United States as either being in “attainment” (meeting primary or secondary ambient air quality standards) or in “nonattainment.”
“After that, implementation is up to the state and local air boards. They all are required to have a certain number of air quality monitors to keep track of pollution and they also handle reviewing permits for new construction, highways or other projects in that county that might affect air pollution,” she said.
Depending upon their size, counties are required under federal law to have air-quality monitoring sites in areas that are likely to have the worst air quality, such as major highways or urban traffic corridors.
Under the revised regulations, counties will be expected to have air-quality monitoring stations in or near at-risk communities, which should help to mitigate inequities that arise from proximity of polluting power plants in less-advantaged locations, Ms. Frank said.
“I think obviously any improvement in air quality is going to benefit everyone who breathes there, which I hope is all of us, but certainly people who already have the most air pollution hopefully should see bigger gains as well,” she said.
All persons interviewed for this article reported no relevant conflicts of interest. Dr. Coates and Dr. Balakrishnan are members of the editorial advisory board for CHEST Physician.