Bad Air Days in Denali, Alaska: 0 a Year

0 bad air days a year

Rare: among the cleanest-air counties EPA monitors. Ranked 954 of 996 monitored counties, where 1 is worst.

What actually helps here

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

Better or worse than it was

In 2000 to 2009 this county averaged under 1 bad days a year; in 2016 to 2025, 0. Not much has changed.

Date	AQI	Main pollutant
2019-08-31	82	PM2.5
2022-06-13	82	PM2.5
2022-07-04	77	PM2.5
2024-06-23	77	PM2.5
2019-06-29	75	PM2.5

An ordinary day in Denali

Across 3,575 monitored days from 2016 to 2025, the air in Denali rated Good on 99% of them, more often than the 72% typical of monitored counties, and Moderate on 1%. The median day sat at AQI 34; one day in ten went above 43.

The pollutant setting the AQI on an ordinary day here:

ozone98%3,503 days
fine particles (PM2.5)2%72 days

Denali by year

Year	Days monitored	Good	Moderate	Median AQI	Highest AQI
2025*	362	361	1	33	54
2024	362	357	5	35	77
2023	350	350	0	33	50
2022	338	328	10	34	82
2021	363	360	3	33	74
2020	358	356	2	33	54
2019	360	355	5	36	82
2018	364	361	3	35	58
2017	360	359	1	34	52
2016	358	357	1	33	54
2015	363	355	8	35	90
2014	341	333	8	31	80
2013	359	357	2	32	58
2012	365	363	2	32	58
2011	365	363	2	34	61
2010	363	363	0	33	49

*2025 may be a partial year in EPA's file.

Alaska compared

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.