From an EPA news release

The USEPA today finalized a significantly stronger air quality standard to better protect America’s families, workers, and communities from the dangerous and costly health effects of fine particle pollution, also known as soot.

By strengthening the annual health-based national ambient air quality standard for fine particulate matter (PM_2.5) from a level of 12 micrograms per cubic meter to 9 micrograms per cubic meter, the U.S. Environmental Protection Agency’s updated standard will save lives — preventing up to 4,500 premature deaths and 290,000 lost workdays, yielding up to $46 billion in net health benefits in 2032. For every $1 spent from this action, there could be as much as $77 in human health benefits in 2032.

Recommendations of the independent advisors comprising the Clean Air Scientific Advisory Committee and CASAC PM expert panel were considered when deciding on whether to strengthen the PM standards.

Based on the scientific evidence, technical information, recommendations from CASAC, and public comments on the 2023 proposed standards, EPA has set two primary standards for PM2.5, which work together to protect public health: the annual standard, which EPA has revised, and a 24-hour standard, which the agency retained. EPA also retained the current primary 24-hour standard for PM10, which protects against coarse particles. EPA is also not changing the secondary (welfare-based) standards for fine particles and coarse particles at this time.

A broad and growing body of science links particle pollution to a range of serious and sometimes deadly illnesses. Many studies show that these microscopic fine particles can penetrate deep into the lungs and that long- and short-term exposure can lead to asthma attacks, missed days of school or work, heart attacks, expensive emergency room visits and premature death.

Due to the efforts that states, Tribes, industry, communities, and EPA have already taken to reduce dangerous pollution in communities across the country, 99% of U.S. counties are projected to meet the more protective standard in 2032, likely the earliest year that states would need to meet the revised standard. That’s even before accounting for additional actions on the horizon to implement the Bipartisan Infrastructure Law and Inflation Reduction Act investments and to update source-specific emission standards. 

See projected progress in 2032.

EPA is also revising the Air Quality Index to improve public communications about the health risks from PM_2.5 exposures.

Some PM is emitted directly from combustion sources, construction sites, industrial processes, and older diesel engines, while other particles are formed in the atmosphere in complex chemical reactions with other pollutants such as sulfur dioxide and nitrogen oxides that are emitted from power plants, gasoline and diesel engines, and certain industrial processes. Particle pollution from industrial processes and other sources is controllable, with readily available and cost-effective technologies to manage emissions, and EPA will build on decades of experience in providing flexible options to states and Tribes across the implementation process.

EPA carefully considered extensive public input as it determined the final standards. The agency held a virtual public hearing and received about 700,000 written comments before finalizing today’s updated air quality standards.

See more information on today’s final standards at Final Reconsideration of the National Ambient Air Quality Standards for Particulate Matter.

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