Aleutians East, Alaska air quality history

Daily Air Quality Index summaries from EPA monitors in Aleutians East, Alaska, 2001–2025.

99%

Good days in 2023

Median daily AQI, 2023

Days above 100 in 2023

121

Days with an AQI in 2023 (of 365)

In 2023, EPA reported a daily Air Quality Index (AQI) for Aleutians East, Alaska on 121 days. 120 of those days (99%) were in the Good range, and the median daily AQI was 11. That median is lower than the typical monitored county in Alaska (median 21 across 7 counties), and lower than the typical monitored U.S. county (43). The main pollutant was fine particles (PM2.5) on 121 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 98% in 2003–2005 versus 99% in 2020–2023.

EPA did not report an AQI for every day of 2023 here (121 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

Years with fewer than 120 monitored days (2015, 2016, 2017, 2021, 2024, 2025…) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median daily AQI
90th-percentile daily AQI

Main pollutant by day, 2023

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

Pollutant	Days as main pollutant	Share of monitored days
Fine particles (PM2.5)	121	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Median AQI	90th pct.	Max AQI	Main pollutant
2025	99	98	1	11	21	58	PM2.5
2024	112	111	1	13	28	53	PM2.5
2023	121	120	1	11	23	55	PM2.5
2022	121	119	2	12	27	74	PM2.5
2021	118	117	1	13	29	51	PM2.5
2020	121	121	0	11	29	41	PM2.5
2019	121	119	2	14	29	55	PM2.5
2018	120	120	0	13	28	46	PM2.5
2017	118	118	0	12	24	38	PM2.5
2016	119	117	2	11	24	59	PM2.5
2015	117	117	0	13	28	44	PM2.5
2014	105	103	2	12	25	61	PM2.5
2013	105	105	0	12	25	46	PM2.5
2012	116	116	0	13	27	48	PM2.5
2011	101	99	2	15	29	57	PM2.5
2010	102	102	0	11	22	45	PM2.5
2009	120	118	2	13	26	59	PM2.5
2008	109	108	1	11	26	52	PM2.5
2007	113	111	2	13	31	61	PM2.5
2006	117	114	3	13	25	67	PM2.5
2005	121	120	1	11	22	51	PM2.5
2004	121	117	4	12	30	60	PM2.5
2003	120	118	2	13	31	65	PM2.5
2002	119	117	2	15	36	55	PM2.5
2001	10	9	1	14	52	52	PM2.5

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

All monitored counties in Alaska

Source: U.S. EPA AirData, “Annual AQI by County” files for 2001–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem