Air quality, as measured by fine particle pollution, improved across much of the country between 2015 and 2021, though it worsened across several Western states and Florida.
Why it matters: Fine particles, generated from fossil fuel-burning and other sources, can enter our bodies when we breathe, making their way to the lungs or bloodstream and causing myriad health problems.
- They are linked to nearly 11,000 excess deaths across the U.S. annually, by one estimate.
- Non-white and low-income Americans are at a higher risk of death from exposure to fine particle pollution compared to other groups, per a 2022 study published in Nature.
- Fine particles — also known as PM2.5 due to their tiny size of 2.5 micrometers — are the most hazardous form of particulate matter.
By the numbers: The three-year rolling annual average concentration of fine particle pollution across the U.S. was 8.5 micrograms per cubic meter as of 2021 (the latest year for which data is available), compared to 13.5 micrograms in 2000 — a 37% decrease.
- Concentrations below 12 micrograms per cubic meter are considered healthy, the EPA says — though it is seeking to tighten that standard.