During the wildfire season, a neonatal intensive care unit doctor smelled smoke in the hospital as polluted air seeped through the filtration systems.[1] The hospital responded by adding more air purifiers and modifying patient care.[1] In January 2023, the US Environmental Protection Agency (EPA) proposed to tighten the annual air quality standard for fine particulate matter PM2.5 from 12 micrograms per cubic meter to 9 to 10 micrograms per cubic meter.[1][2][3][4][7] This proposal is based on a scientific review that showed that the original limit did not adequately protect public health.[4] On February 7, 2024, the EPA finally set this standard at 9.0 micrograms per cubic meter, strengthening protection against the harmful effects of soot related to heart disease and premature death.[3][5][6] The daily standard for PM2.5 (35 micrograms per cubic meter) and the standards for PM10 have not changed.[3][5][6] At the same time, the EPA revised its air quality index and monitoring requirements to better protect polluted communities.[3][4][6]