#1
Kihei, HI
PM2.5: 2.9 Unhealthy Days: 0%
Grade A
89.8
Score
Top 10 Cleanest Cities in the US (2026)
These cities have the highest Clean Air Scores based on annual PM2.5 levels, consistency, and long-term improvement trends.
How to read this ranking: Cities are ordered by their overall Clean Air Score (0-100), combining annual PM2.5 averages, unhealthy days, and 5-year trends. A higher score means consistently cleaner air and lower health risks. Want to know exactly how we calculate this? Read our full methodology.
#2
Mountain View, HI
PM2.5: 2.1 Unhealthy Days: 0%
Grade A
89.8
Score
#3
Naalehu, HI
PM2.5: 2.9 Unhealthy Days: 0%
Grade A
89.8
Score
#4
Not in a city, HI
PM2.5: 3.4 Unhealthy Days: 0%
Grade A
89.8
Score
#5
Hilo, HI
PM2.5: 2.7 Unhealthy Days: 0%
Grade A
89.7
Score
#6
Carmel Valley Village, CA
PM2.5: 5 Unhealthy Days: 0%
Grade A
89.6
Score
#7
Honolulu, HI
PM2.5: 4.1 Unhealthy Days: 0%
Grade A
89.6
Score
#8
Kealakekua, HI
PM2.5: 2.1 Unhealthy Days: 0%
Grade A
89.6
Score
#9
Anacortes, WA
PM2.5: 4.4 Unhealthy Days: 0%
Grade A
89.6
Score
#10
Bremerton, WA
PM2.5: 3.9 Unhealthy Days: 0%
Grade A
89.6
Score
How do we rank cities?
Our Clean Air Score measures long-term air quality stability, factoring in annual PM2.5 levels, frequency of unhealthy days, and 5-year improvement trends. Data is sourced strictly from official EPA sensors.