The air pollution and PM2.5 emissions from wildfires are so severe that they outweigh any reduction in man-made air pollution, negatively impacting fetuses.

While man-made air pollution is being contained through various efforts, it has been pointed out that the increase in wildfires is resulting in a corresponding increase in air pollution. In particular, it is said that unborn fetuses are at increased risk of premature birth and diseases later in life.

Frontiers | Wildfire contributions to prenatal PM2.5 exposure in the contiguous United States, 2003–2019
https://www.frontiersin.org/journals/environmental-health/articles/10.3389/fenvh.2026.1838836/full

Wildfire Smoke Is Now a Bigger Prenatal Threat Than Human Sources of Air Pollution - Inside Climate News
https://insideclimatenews.org/news/07082026/wildfire-smoke-pollution-prenatal-threat/

In the United States, the Clean Air Act was amended under President Nixon's administration in 1970, tightening regulations on automobile emissions. As a result, it has been reported that emissions of major pollutants decreased by 78% by 2020.

Air Pollution Trends Continue to Link Clean Air and Strong Economy | US EPA
https://www.epa.gov/newsreleases/air-pollution-trends-continue-link-clean-air-and-strong-economy

However, researchers at the University of Maryland, College Park, point out that these efforts are being negated by the smoke generated by the wildfires, which is worsening air quality. They say that low-income groups, rural areas, Indigenous peoples, and unborn children are particularly affected.

The research team examined Environmental Protection Agency (EPA) air pollution data to see how anthropogenic and wildfire-induced air pollution had changed across the continental United States. They also compared this data with birth records to investigate the effects on fetuses.

According to the analysis, between 2003 and 2019, the average daily exposure to air pollution for prenatal fetuses decreased by 37%, but the contribution of wildfires to pollution doubled, offsetting the decrease.

This study did not consider factors such as whether the mother was wearing an N95 mask, whether there were air purifiers or other systems in the home, or how much time the mother spent outdoors exposed to air pollution, and senior author Michel Boudreau acknowledges the limitations of the study in these respects. On the other hand, he points out that data sources tracking wildfire smoke have shown that pollution, such as PM2.5, is being detected inside people's homes.

According to Boudreau, exposure to wildfire smoke early in life is likely to lead to lifelong health problems.

Boudreau also expressed concern about the increasing number of days with acute and large-scale air pollution that endangers fetuses, and stated that the next area of focus is how to help people manage their exposure to wildfire smoke.