Grade A Air Quality Cities
50 cities with excellent air quality
Grade A means consistently clean air with minimal health risk and improving or stable trends. These cities are scored using 10 years of EPA Air Quality System data, weighted across 5-year median AQI (40%), trend direction (30%), unhealthy days per year (20%), and worst-pollutant severity (10%).
What "Grade A" Actually Means
A Grade A means a city posts a 5-year median AQI well within the EPA "Good" category (typically AQI 30-45), with improving or stable trends, very few unhealthy days, and a dominant pollutant from the lower-risk end of the spectrum. These are the cleanest U.S. cities tracked by EPA monitoring — the air-quality benchmark.
No one needs to change behavior in a Grade A city based on outdoor air. Even people with severe asthma, COPD, recent cardiac events, pulmonary fibrosis, or compromised immunity can exercise outdoors, open windows, and let kids play freely. The exception is the rare wildfire smoke or industrial event that briefly pushes a normally-clean city out of range.
Grade A and Daily Life
Run, bike, garden, hike, sit on the porch — Grade A means none of that triggers air-quality concerns. Schools hold outdoor recess and athletics without restriction. Hospitals do not see ER admissions tied to air pollution. Outdoor workers in Grade A cities have one less health risk to manage.
Long-Term Health Picture
Cities that hold Grade A year over year have some of the lowest rates of asthma, COPD, lung cancer, and cardiovascular mortality in the developed world. Long-term residence is associated with measurably longer life expectancy — Harvard cohort research consistently finds 0.5 to 1.0 years of additional life expectancy for each 10-µg/m³ reduction in long-term PM2.5 exposure.
Where Grade A Cities Cluster
Grade A cities tend to cluster in coastal areas with steady ocean ventilation (much of the Pacific Northwest and Northeast outside summer ozone), high-elevation mountain towns away from valleys, and rural areas without major industrial sources. The common factor: geography that disperses pollution rather than trapping it.
Among the 50 Grade A cities tracked here, the largest concentrations are in PR (5), VA (5), AK (4), CO (3), IN (3). The dominant pollutant in these cities is PM2.5 (21 cities), followed by PM10 (15), Ozone (10).
All Grade A Cities
Frequently Asked Questions
A Grade A means a city posts a 5-year median AQI well within the EPA "Good" category (typically AQI 30-45), with improving or stable trends, very few unhealthy days, and a dominant pollutant from the lower-risk end of the spectrum. These are the cleanest U.S. cities tracked by EPA monitoring — the air-quality benchmark.
50 of 1,020 monitored US cities currently have a Grade A Air Quality rating, representing 4.9% of all tracked areas.
No one needs to change behavior in a Grade A city based on outdoor air. Even people with severe asthma, COPD, recent cardiac events, pulmonary fibrosis, or compromised immunity can exercise outdoors, open windows, and let kids play freely. The exception is the rare wildfire smoke or industrial event that briefly pushes a normally-clean city out of range.
Run, bike, garden, hike, sit on the porch — Grade A means none of that triggers air-quality concerns. Schools hold outdoor recess and athletics without restriction. Hospitals do not see ER admissions tied to air pollution. Outdoor workers in Grade A cities have one less health risk to manage.
Grade A cities tend to cluster in coastal areas with steady ocean ventilation (much of the Pacific Northwest and Northeast outside summer ozone), high-elevation mountain towns away from valleys, and rural areas without major industrial sources. The common factor: geography that disperses pollution rather than trapping it.
/methodology
The this entity category groups every U.S. air quality and pollution monitoring entity sharing this attribute. The list above is the data; the paragraphs below explain what the grouping means against the broader the EPA Air Quality System (AQS) distribution and how to read the relative rankings within the category.
For readers using this category as a starting point, the per-entity detail pages linked from the table above carry the underlying the EPA Air Quality System (AQS) data in full. The category-level view is the filter; the per-entity pages are the actual answer.
Source: EPA Outdoor Air Quality Data, 2026.