What does the Air Quality Index actually measure?

The AQI summarizes common pollutants like particulate matter and ozone into a single daily scale, where lower is cleaner and healthier. This ranking uses the annual median, so it reflects a typical day rather than the worst one; our methodology page explains the source.

Does this account for wildfire season?

Not well. A median annual figure smooths over short, severe smoke events, so a metro with generally clean air can still face rough wildfire stretches. If that's a concern, look at seasonal air-quality patterns for the specific region.

How much should air quality affect my decision?

It depends on your health and who's in your household; for people with respiratory conditions or young kids, it can be a top factor. For others it's one input among many, so weigh it alongside cost, jobs, and the other rankings in our compare tool.

Cleanest air

Metros with the lowest median air quality index — cleaner air, by EPA monitoring.

Top 50 of 300 metros, ranked by our published formula.

Air quality is one of the few location factors with a direct, well-documented link to physical health, and it's largely outside your control once you've chosen a metro. This ranking uses the EPA's annual median Air Quality Index, where a lower number means cleaner everyday air, which matters most for children, older adults, and anyone with asthma or other respiratory conditions. Unlike cost or income, you can't negotiate or budget your way around the air you breathe, so it deserves real weight for sensitive households.

Read the top of the list as metros with the cleanest typical air over a year, but remember the median is a middle value that smooths over bad days. The honest caveat: this won't capture seasonal wildfire smoke, short pollution spikes, or how much air quality varies between a downtown corridor and a leafy suburb within the same metro. Use it as a baseline, then look at seasonal patterns and your specific neighborhood if air is a priority.

Common questions

What does the Air Quality Index actually measure?: The AQI summarizes common pollutants like particulate matter and ozone into a single daily scale, where lower is cleaner and healthier. This ranking uses the annual median, so it reflects a typical day rather than the worst one; our methodology page explains the source.
Does this account for wildfire season?: Not well. A median annual figure smooths over short, severe smoke events, so a metro with generally clean air can still face rough wildfire stretches. If that's a concern, look at seasonal air-quality patterns for the specific region.
How much should air quality affect my decision?: It depends on your health and who's in your household; for people with respiratory conditions or young kids, it can be a top factor. For others it's one input among many, so weigh it alongside cost, jobs, and the other rankings in our compare tool.