The "State of the Air" 2025 report reveals that 46% of Americans — 156.1 million people — live in areas with unhealthy levels of ozone and particle pollution, especially super-small particles called PM2.5. 

Short-term exposure (up to 24-hours) to these small particles from traffic, construction, industry, or soot is associated with more emergency room visits and hospital admissions for heart problems, bronchitis, and asthma.

In the long term, the negative impact of small particle exposure is far-reaching. One study of more than half a million newborns found a consistent association between low birth weight and moms living in areas with heavy traffic congestion.

Another looked at data on 30 million people and found that small particle pollution can raise the risk for dementia by 13% or more. 

Luckily, you can clear the air — at least at home. A study in the Journal of the American College of Cardiology found that using a HEPA air filter in the bedroom and living room for one month reduced people’s systolic blood pressure (the top number) by almost 3 mmHg, and may cut your risk of heart failure by 10% to 20%.

That benefit was seen in people whose top number started out at 120 or higher. That’s around half of Americans, including 83% of those over age 80, who are most at risk of disability from heart failure.

If you live near busy roadways or industrial areas (or contend with wildfire smoke), consider getting HEPA air filters.