Today, on February 7, 2024, U.S. EPA announced its final air quality standard to govern fine particulate matter (PM 2.5), also known as soot.  More specifically, U.S. EPA set an annual health-based national ambient air quality standard for PM 2.5 of 9 micrograms per cubic meter.  This is a significant reduction from the previous standard of 12 micrograms per cubic meter.

In addition to strengthening the annual standard, U.S. EPA also modified the PM 2.5 monitoring network design criteria in order to improve data collection to account for environmental justice considerations.  This modification is intended to account for proximity of populations at increased risk of health effects from PM 2.5 to sources of air pollution.

U.S. EPA estimates that the new, stricter PM 2.5 standard will help prevent up to 4,500 premature deaths and 290,000 lost workdays, and yield up to $46 billion in net health benefits in 2032.

U.S. EPA also maintains a separate 24-hour PM 2.5 standard, which protects against coarse particles.  U.S. EPA has not revised this standard, currently set at 35 micrograms per cubic meter.

U.S. EPA estimates that the earliest possible year that states would need to demonstrate attainment of the standards is 2032.

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