Map Shows the Best and Worst States for Air Quality, and a Southern State Ranks Last

Air quality makes a big difference when it comes to your overall health, but gauging it isn’t as simple as looking out your window. This map reveals disparities in air quality throughout the U.S., from big urban centers to rural areas.

1. States With the Best and Worst Air Quality, Mapped
2. U.S. Cities With the Most and Least Air Pollution

The team at HouseFresh determined this information by examining the average concentration of PM2.5 (fine particulate matter) across different U.S. states and cities. Fine particulate matter is made up of combination of particles in the air that are 2.5 microns or less in diameter. It can range from dry solid fragments to liquid droplets and is usually produced by burning gasoline, oil, diesel fuel, or wood. PM2.5 is more likely to travel deeper into the lungs compared to larger particles, potentially causing tissue damage and lung inflammation.

The researchers pulled data from IQAir’s Air Quality Index to calculate the average PM2.5 concentration across the U.S. in 2024. They also made sure to take into account that bigger cities contributed more to the state average.

States With the Best and Worst Air Quality, Mapped

The South tends to be worse off; many states in the region have a PM2.5 concentration that’s close to or above 8 µg/m³ (micrograms per cubic meter). Georgia has the poorest air quality, with an average PM2.5 concentration of 8.9 µg/m³. That’s well over the WHO Global Air Quality Guidelines, which max out at 5 µg/m³. The northern state with the worst air quality is Idaho at 8.7 µg/m³.

Here are the top 10 states with the worst air quality:

On the flip side, Hawaii has the best air quality in the country. The Aloha State boasts an average PM2.5 concentration of 3.4 µg/m³. That said, many states in the north generally have better air quality, according to this study. Alaska and Rhode Island are the runners-up with 3.6 µg/m³ each. 

The states with the best air quality overall are as follows:

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U.S. Cities With the Most and Least Air Pollution

Things get more interesting when you zoom in closer to the data. While Idaho is one of the worst states for air pollution overall, Nampa is the only city from the state on the list for the top 10 cities with the worst air quality. Californian cities take up nine spots, with Ontario having the highest PM2.5 concentration. It’s well above the national average at 14.3 µg/m³.

These cities top the charts for the worst air quality:

Surprisingly, the Golden State has five cities that also ended up on the list of places with the best air quality in the state. Additionally, no Southern cities made it on the list, despite the region’s poor numbers on the map above.

Here are the top 10 cities that have the least air pollution: