Overview
- The national study, published Friday, found that by 2019 roughly 65% of days when pregnant people experienced PM2.5 above the EPA unhealthy threshold were attributable to wildfire smoke.
- Researchers modeled exposures for about 64.5 million pregnancies across 2,842 counties in 48 states using two simulations—one with all emissions and one with fire emissions removed—to isolate wildfire contributions.
- Across 2003–2019 average prenatal PM2.5 fell about 34%, but excluding fires the decline was about 37%, showing wildfire smoke has partly offset regulatory air-quality gains.
- The growing fire share hit some places and people harder: the Northwest and Western states saw the largest rises and low-income, rural, American Indian and Alaska Native communities and areas with few maternity services faced the heaviest burdens.
- Authors note the study ends in 2019, warn that major post-2019 seasons make continued rises in fire-attributable prenatal exposure plausible, and call for updated data plus targeted interventions such as air filtration, monitoring, and resource allocation to vulnerable areas.