Bad Air Days in Archuleta County, Colorado: under 1 a Year

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 707 of 996 monitored counties, where 1 is worst.

What makes them bad: a mix of particles and ozone (56% particle days).

When the bad days come in Archuleta

Most bad days here fall in April and May. Averaged over 2016 to 2025.

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.

The record for Archuleta

In 2000 to 2009 this county averaged under 1 bad days a year; in 2016 to 2025, under 1. Not much has changed. The worst recent year was 2022, with 4 bad days on 365 monitored days.

Date	AQI	Main pollutant
2022-05-09	227	PM10
2022-05-08	144	PM10
2019-08-31	124	Ozone
2023-04-03	120	PM10
2025-06-18	115	Ozone

Most days, not the worst ones

Across 3,625 monitored days from 2016 to 2025, the air in Archuleta County rated Good on 88% of them, more often than the 72% typical of monitored counties, and Moderate on 11%. The median day sat at AQI 35; one day in ten went above 52.

The pollutant setting the AQI on an ordinary day here:

ozone68%2,460 days
coarse dust (PM10)28%1,009 days
fine particles (PM2.5)4%149 days

Archuleta County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	364	302	60	2	0	34	115
2024	366	349	17	0	0	32	80
2023	365	349	15	1	0	35	120
2022	365	313	48	4	1	42	227
2021	365	269	96	0	0	45	93
2020	365	302	63	0	0	43	93
2019	363	331	30	2	0	31	124
2018	365	333	32	0	0	38	97
2017	360	311	49	0	0	36	93
2016	347	343	4	0	0	17	82
2015	348	342	6	0	0	17	74
2014	336	335	1	0	0	17	51
2013	314	305	6	3	1	17	171
2012	332	326	6	0	0	19	97
2011	339	333	6	0	0	17	78
2010	310	298	7	5	1	17	198

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

Nearby counties on file

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, and on why a purifier does not touch ozone in smoke vs ozone.