Air Quality Rankings for Hawaii (2026)
Hawaii has 4 cities tracked by EPA air-quality monitors, with a state-wide 5-year median AQI of 23 — 18 points cleaner than the national average of AQI 41. Kauai, Hawaii ranks #1 with the cleanest air (AQI 15, Grade A), while Honolulu, Hawaii sits at the bottom (AQI 29, Grade B).
How Hawaii Compares
Hawaii has 4 cities tracked by EPA air-quality monitors, with a state-wide 5-year median AQI of 23 — 18 points cleaner than the national average of AQI 41. Kauai, Hawaii ranks #1 with the cleanest air (AQI 15, Grade A), while Honolulu, Hawaii sits at the bottom (AQI 29, Grade B). The rankings below are computed from the EPA Air Quality System (AQS), which aggregates daily AQI readings from federally certified monitors into annual averages. Cities are sorted by 5-year median AQI (lowest = cleanest = #1). The 5-year window smooths out year-to-year volatility from weather and wildfire events.
Hawaii is on an improving trajectory: 4 of 4 monitored cities show measurably cleaner air over the past decade, against just 0 that are getting worse. That mirrors the broader national pattern of falling particulate and ozone pollution as cleaner vehicles, cleaner power generation, and tighter industrial standards take effect.
The dominant pollutant across 3 of 4 Hawaii cities is Fine Particulate Matter (PM2.5). PM2.5 (fine particulate matter) is most often driven by combustion sources — vehicle exhaust, industrial emissions, residential wood burning, and increasingly wildfire smoke. It penetrates deep into lung tissue and the bloodstream and is the air pollutant most strongly linked to long-term health impacts. Other Hawaii cities report Ground-Level Ozone (1) as their dominant concern.
The fastest-improving city in Hawaii is Hawaii, Hawaii, with median AQI falling by 5.2 points per year. Steady improvement at that pace usually reflects fleet turnover (older diesels retiring), upwind power-plant retirements, or tighter regional emissions controls.
Full Hawaii Ranking
| # | City | 5yr Avg AQI | Current AQI | Worst Pollutant | Trend | Grade |
|---|---|---|---|---|---|---|
| 1 | Kauai, Hawaii | 15 | 13 | PM2.5 | Improving | A |
| 2 | Maui, Hawaii | 21 | 20 | PM2.5 | Improving | A |
| 3 | Hawaii, Hawaii | 25 | 23 | PM2.5 | Improving | A |
| 4 | Honolulu, Hawaii | 29 | 31 | Ozone | Improving | B |
Air quality data for Hawaii is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
Frequently Asked Questions
Kauai, Hawaii has the best air quality in Hawaii with a 5-year average AQI of 15 and a Grade A (82/100). Its dominant pollutant is Fine Particulate Matter (PM2.5) and the long-run trend is improving.
Honolulu, Hawaii has the worst air quality in Hawaii with a 5-year average AQI of 29 and a Grade B (76/100). Its dominant pollutant is Ground-Level Ozone.
Hawaii has 4 cities with EPA air quality monitoring data, covering 2014-2023 of daily AQI measurements aggregated into annual averages.
Hawaii's state-wide 5-year median AQI is 23, 18 points cleaner than the national average of AQI 41. Hawaii is on an improving trajectory: 4 of 4 monitored cities show measurably cleaner air over the past decade, against just 0 that are getting worse. That mirrors the broader national pattern of falling particulate and ozone pollution as cleaner vehicles, cleaner power generation, and tighter industrial standards take effect.
Fine Particulate Matter (PM2.5) is the dominant pollutant in 3 of 4 monitored Hawaii cities. PM2.5 (fine particulate matter) is most often driven by combustion sources — vehicle exhaust, industrial emissions, residential wood burning, and increasingly wildfire smoke. It penetrates deep into lung tissue and the bloodstream and is the air pollutant most strongly linked to long-term health impacts.
Hawaii cities log an average of 0 days per year at "Unhealthy for Sensitive Groups" or worse, based on EPA monitor data over the last five years. Across all 4 Hawaii cities tracked, that totals 6 unhealthy days over the period.
Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.
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.