OAKLAND — California Attorney General Rob Bonta today led a coalition of state attorneys general and New York City in submitting a comment letter urging the U.S. Environmental Protection Agency (EPA) to adopt stringent standards under the Clean Air Act that protect public health against particulate matter (PM) pollution. These standards, known as the National Ambient Air Quality Standards (NAAQS), are critical to California’s efforts to improve air quality and the health of residents disproportionately impacted by some of the highest PM levels in the nation. Particulate matter is a pollutant emitted from a variety of sources including vehicles, factories, and construction sites. Also referred to as soot, PM is a mixture of microscopic solids and liquid droplets suspended in the air that can cause serious health problems. In today’s comment letter, Attorney General Bonta calls for more protective federal standards for PM pollution to ensure healthier levels of air quality for Californians.

“High particulate matter pollution levels are a serious threat to public health, particularly for underserved and vulnerable populations,” said Attorney General Bonta. “Today’s comment letter urges the EPA to set adequate standards to ensure that all Californians can breathe clean air. The adoption of stronger standards will aid all of California's communities, but especially communities experiencing environmental injustices, that are disproportionately affected by air pollution. At the California Department of Justice, we will continue advocating for stronger pollution control measures for the wellbeing of all Californians.”

Under the Clean Air Act, the EPA is required to set NAAQS for several pollutants, including PM, at a level that protects public health and welfare. Once the NAAQS are set, states are tasked with implementing those standards. The EPA has now proposed new PM NAAQS to replace standards originally issued many years ago — and which the Trump Administration refused to lower despite overwhelming evidence that certain standards failed to protect the public health and welfare as required by the Clean Air Act. In 2021, the California Department of Justice sued the Trump Administration over its refusal to update the PM NAAQS, and has since successfully petitioned the EPA to reconsider that decision.

Exposure to PM causes significant health impacts, including increased rates of heart disease, serious respiratory impacts, and increased death rates. In particular, smaller PM particles are easily inhalable and therefore pose the greatest risk to health. Both long-term and short-term exposure to such particles have been shown to cause extremely harmful health impacts. Long-term exposure, such as that experienced by people living for many years in areas with high PM levels, has been associated with premature death, reduced lung function, and the development of chronic bronchitis. Short term exposure to particles — for hours or days — can aggravate lung disease, causing asthma attacks, acute bronchitis, and increased susceptibility to respiratory infections. Children, the elderly, and people with preexisting heart and lung disease are the most susceptible to PM exposure. 

In the comment letter, the attorneys general urge the EPA to take long-necessary action and adopt strict standards for particulate matter pollution to protect human health in all communities, including sensitive populations and communities that have historically suffered disproportionately severe PM exposure.  

In filing the comment letter, Attorney General Bonta is joined by the attorneys general of Connecticut, Delaware, Illinois, Maryland, Massachusetts, Michigan, Minnesota, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Vermont, Washington, Wisconsin, the District of Columbia, and the City of New York. 

Attorney General Bonta is committed to safeguarding California’s public welfare and environment. In January 2023, Attorney General Bonta and the California Air Resources Board led a multistate coalition challenging EPA’s failure to adopt more protective standards for particulate matter emissions from airplanes to address disproportionate environmental burdens in underserved communities.

A copy of the comment letter can be found here.