New Hampshire Counties Are Some Of The Cleanest For Pollution, New Report Says

NEW HAMPSHIRE — Some areas of New Hampshire are some of the best locations in the country for year-round particle pollution, according to the American Lung Association’s 2025 “State of the Air.”

The report noted that after decades of progress in reducing the two major air pollutants, 156.1 million people — 46 percent of all Americans — are living in places that get failing grades for unhealthy levels of ground-level ozone pollution, or smog, and fine particle pollution, or soot. They are two of the most widespread and dangerous of pollutants.

But not in New Hampshire.

According to the study, two counties are among the Top 25 cleanest in the nation: Hillsborough County ranked 10th while Belknap County was 21st. Belknap and Grafton counties were also on a list of the cleanest counties for air pollution.

“This is nearly 25 million more people breathing unhealthy air compared to last year’s report, and more than in any other ‘State of the Air’ report in the last ten years,” according to the report. “Extreme heat, drought and wildfires are contributing to worsening levels of air pollution across much of the U.S., exposing a growing proportion of the population to ozone and particle pollution that put their health at risk.”

Ground-level ozone causes more breathing difficulties than any other single pollutant, according to the report. From 2021 through 2023, 37 percent of the population — about 125.2 million people — were exposed to unhealthy levels of ozone. That’s 24.6 million more people than reported in last year’s air-quality study.

In New Hampshire, Belknap and Grafton counties had no high ozone days during that time period. Cheshire and Merrimack counties had a single day each of Orange ranking. Hillsborough County had two days, while Coos and Rockingham counties had four days each. No county in New Hampshire had Red or Purple alert Ozone days.

The number of people living in counties that earned an “F” grade for unhealthy spikes in fine particle pollution increased to 77.2 million, up 12.1 million people from last year’s report. This is the seventh straight year this deadly pollutant increased, according to the American Lung Association.

Since 2000, the American Lung Association report has tracked the successes of the Clean Air Act, including reductions over time in emissions from transportation, power plants and manufacturing. However, climate change is making it harder to protect air quality and human health, the organization said.

For years, the worst air pollution problems were in western states, but the 2025 report found the geographic distribution of air pollution shifting back East. The year 2023 saw improved conditions along the West Coast, but also a deadly heat wave in Texas and an unprecedented blanket of smoke from wildfires in Canada that drove levels of ozone and particle pollution in dozens of central and eastern states higher than they have been in many years.

Both smog and soot can cause premature death and other serious health conditions, such as asthma attacks, heart attacks, strokes, preterm babies, impaired cognitive function later in life and lung cancer.

The report noted that the burden of living with unhealthy air is not shared equally and that communities of color are disproportionately exposed to air pollution and are more than likely living with one or more chronic health conditions that make them vulnerable.

People of color make up 41.2 percent of the U.S. population, but 50.2 percent of those living in a place with at least one failing grade on the air quality report card. Notably, Hispanic individuals are nearly three times as likely as white individuals to live in a community with three failing grades, the report said.