What’s going on with particulate matter regulation?

Nov 2022 update. The World Health Organization (WHO) reduced exposure guidelines for PM 2.5 concentrations to 5 ppm in 2021. https://www.who.int/news-room/feature-stories/detail/what-are-the-who-air-quality-guidelines

The World Health Organization maintains that clean air is a basic human right. Yet, air pollution continues to pose a significant threat to people worldwide – it is the greatest environmental threat to health and a leading cause of non-communicable diseases (NCDs) such as heart attacks or stroke. Fine particulate matter (PM2.5) can penetrate through the lungs and further enter the body through the blood stream, affecting all major organs. Exposure to PM2.5 can cause diseases both to our cardiovascular and respiratory system, provoking, for example stroke, lung cancer and chronic obstructive pulmonary disease (COPD). 

New research has also shown an association between prenatal exposure to high levels of air pollution and developmental delay at age three, as well as psychological and behavioural problems later on, including symptoms of attention deficit hyperactivity disorder (ADHD), anxiety and depression. The 2021 update of the WHO air quality guidelines is in response to the real and continued threat of air pollution to public health.

Meanwhile, the US lags behind and standards are not protective.

For years scientists have warned that national standards under the Clean Air Act provide inadequate public health protections. Last year Harvard researchers connected thousands of premature deaths in the U.S. to coal, biomass, natural gas and other energy-related combustion sources, while a 2022 Health Effects Institute report found that exposure to PM2.5 concentrations below current standards causes mortality in older Americans.

The Clean Air Act requires EPA to revisit its standards every five years to ensure they keep pace with science. But the last change came back in 2012, when the Obama EPA lowered the acceptable limit of ambient PM2.5 from 15 to 12 micrograms per cubic meter.

In 2019, after the Trump administration took office, EPA scientists recommended lowering the standard again, saying that a range of 8-10 micrograms could save up to 12,000 lives each year.

“But the Trump administration blasted forward with their review,” says Seth Johnson, a senior attorney with Earthjustice. Ultimately, the Trump administration declined to toughen standards.

Coal industry backers lauded the Trump decision. Earthjustice, meanwhile, sued the EPA on behalf of a coalition of groups that included the American Lung Association and Union of Concerned Scientists.

“All these groups said the science shows that people die at current PM2.5 standards,” says Johnson.

Soon after the Biden administration took office, the new EPA leadership announced a course change and in 2022 published a supplement to the scientific reports used under Trump. It further supported strengthening PM2.5 standards, which the Biden EPA hopes to finalize next year. The administration has also proposed new rules to reduce PM2.5 and other pollutants from heavy duty trucks beginning in the 2027 model year.

To Johnson, addressing both transportation and stationary sources such as power plants will help attain lower PM2.5 levels.

Johnson also sees the environmental justice angle highlighted by St. Julien.

“It’s a really big deal,” he says, noting that the Clean Air Act is supposed to protect outdoor air for all groups, but that it obviously falls short for certain communities. But Johnson says he sees building awareness of the dangerous inequality.

The Biden administration also sees the problem. A 2022 policy assessment conducted as part of the current PM2.5 changes acknowledges strong evidence of racial and ethnic disparities in PM2.5 exposure, EPA spokesman Tim Carroll says by email. He added that in 2022 EPA identified strategies to ensure PM2.5 standards are met in communities with low socio-economic status.