Smoke: keep one room clean
Shut the windows and run an air purifier sized for the room.
Wildfire smoke guide →Air quality in Hawaii, county by county
3 Hawaii counties have enough EPA monitor data to count bad-air days. Weighted by population, they averaged about 0 days a year from 2021 to 2025 when the air was unhealthy for sensitive groups or worse.
Every Hawaii county with monitors
Most bad-air days first. 3 have a full report. Compare with the worst and the cleanest counties in the US.
| County | Bad-air days a year | |
|---|---|---|
| Maui CountyKahuluiRarely badozone not measured | 0.4 | |
| Honolulu CountyHonoluluRarely bad | 0.2 | |
| Hawaii CountyHiloRarely badozone not measured | 0.0 | |
| No Hawaii county with a monitor matches “”. Counties without a monitor aren't listed; a neighbor's numbers are a fair guide, or find it on the map. | ||
Counties without a monitor aren't listed. Air doesn't stop at the county line, so a neighbor's numbers are a fair guide.
What helps on a bad-air day
Check AirNow for today's reading and tomorrow's forecast, then match the step to the pollutant.
Upgrade the furnace filter
MERV 13 catches far more smoke than thin fiberglass filters.
Furnace filters →Questions people ask about air quality in Hawaii
Which county in Hawaii has the worst air?
No Hawaii county with a monitor averaged more than about 1 bad-air day a year from 2021 to 2025. Maui County was highest, at 0.4 a year.
How often is the air bad in Hawaii?
Weighted by population, Hawaii counties with monitors averaged fewer than 1 bad-air day a year from 2021 to 2025 with an AQI over 100, when children, older adults and people with asthma should cut back outdoors.
Which county in Hawaii has the cleanest air?
Of the 3 counties with enough monitor data, Hawaii County had the fewest, with no bad-air days at all from 2021 to 2025. Counties without monitors aren't ranked.
Where can I check today's air quality in Hawaii?
AirNow, run by the EPA and its partners, shows current readings and forecasts by ZIP code, and its fire and smoke map adds smoke plumes and low-cost sensors.
Sources: EPA AirData county AQI summaries, 2021 to 2025; CDC Environmental Public Health Tracking Network modeled PM2.5 and ozone, 2018 to 2022. Updated November 8, 2026.