#1
Hilo, HI
PM2.5: 2.7 Unhealthy Days: 0% Trend: improving
Grade A
89.7
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.
national cleanest 2026 ranking, generated from the latest CleanAirData city score dataset
How to read this ranking: Cities are ordered by Clean Air Score, which combines annual PM2.5, unhealthy-day frequency, long-term trend, variability, and extreme-event indicators. Higher scores indicate cleaner and more consistent air quality. Want to know exactly how we calculate this? Read our full methodology.
Data note: Based on CleanAirData Clean Air Scores derived from EPA/AirNow PM2.5, unhealthy-day frequency, long-term trend, and data completeness fields available in the city score dataset.
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#2
Honolulu, HI
PM2.5: 4.1 Unhealthy Days: 0% Trend: neutral
Grade A
89.6
Score
#3
Anacortes, WA
PM2.5: 4.4 Unhealthy Days: 0% Trend: improving
Grade A
89.6
Score
#4
Bremerton, WA
PM2.5: 3.9 Unhealthy Days: 0% Trend: improving
Grade A
89.6
Score
#5
Kailua, HI
PM2.5: 2.9 Unhealthy Days: 0% Trend: improving
Grade A
89.5
Score
#6
San Luis Obispo, CA
PM2.5: 3.9 Unhealthy Days: 0% Trend: improving
Grade A
89.4
Score
#7
Pueblo, CO
PM2.5: 4.7 Unhealthy Days: 0% Trend: neutral
Grade A
89.4
Score
#8
Portland, OR
PM2.5: 4.9 Unhealthy Days: 0% Trend: improving
Grade A
89.4
Score
#9
Vancouver, WA
PM2.5: 4.5 Unhealthy Days: 0% Trend: improving
Grade A
89.4
Score
#10
Apache Junction, AZ
PM2.5: 4.5 Unhealthy Days: 0% Trend: neutral
Grade A
89.3
Score
Related air quality data
Ranking FAQ
How is the cleanest cities ranking calculated?
Cities are ordered by Clean Air Score, which combines annual PM2.5, unhealthy-day frequency, long-term trend, variability, and extreme-event indicators. Higher scores indicate cleaner and more consistent air quality.
What data source does this ranking use?
Based on CleanAirData Clean Air Scores derived from EPA/AirNow PM2.5, unhealthy-day frequency, long-term trend, and data completeness fields available in the city score dataset.
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.