Bad Air Days in Stevens County, Washington: 9 a Year

9 bad air days a year

More bad air days than three quarters of monitored counties. Ranked 102 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (100% particle days).

The bad-air season here

Most bad days here fall in August and September. Averaged over 2016 to 2025.

What to buy, and what not to

Particles (wildfire smoke, dust) cause enough bad days here to matter. A HEPA purifier sized to your bedroom removes them; run it with windows shut on bad days.
Upgrade the furnace or AC filter to MERV 13 so the whole house is filtered, not just one room.

The worst days on file

In 2000 to 2009 this county averaged 2 bad days a year; in 2016 to 2025, 9. It has got worse. The worst recent year was 2017, with 17 bad days on 365 monitored days.

Date	AQI	Main pollutant
2020-09-13	957	PM2.5
2020-09-14	709	PM2.5
2020-09-12	642	PM2.5
2020-09-15	424	PM2.5
2023-08-20	271	PM2.5

An ordinary day in Stevens

Across 3,653 monitored days from 2016 to 2025, the air in Stevens County rated Good on 61% of them, less often than the 72% typical of monitored counties, and Moderate on 37%. The median day sat at AQI 41; one day in ten went above 68.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)93%3,408 days
coarse dust (PM10)7%245 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	252	104	9	6	35	243
2024	366	257	109	0	0	34	98
2023	365	204	153	8	4	46	271
2022	365	208	149	8	1	43	153
2021	365	203	146	16	10	44	223
2020	366	219	138	9	8	42	957
2019	365	223	141	1	0	36	146
2018	365	200	148	17	9	46	220
2017	365	195	153	17	9	47	201
2016	366	254	110	2	0	34	110
2015	362	224	126	12	2	36	161
2014	365	223	138	4	1	39	155
2013	365	215	149	1	0	42	101
2012	366	216	150	0	0	43	88
2011	363	226	136	1	0	34	107
2010	365	223	142	0	0	41	89

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

Elsewhere in Washington

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.