Daily Air Quality Index summaries from EPA monitors in Archuleta, Colorado, 1985–2025.
83%
Good days in 2025
34
Median daily AQI, 2025
2
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Archuleta, Colorado on 364 days. 302 of those days (83%) were in the Good range, and the median daily AQI was 34. That median is lower than the typical monitored county in Colorado (median 46 across 27 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 186 days. Across the years with fuller monitoring, the share of Good days rose: an average of 65% in 1985–1992 versus 91% in 2023–2025.
Years with fewer than 120 monitored days (1987, 1988, 1989, 1990, 1991) 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, 2025
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
Ozone
186
51%
Fine particles (PM2.5)
149
41%
Coarse particles (PM10)
29
8%
Year-by-year data
Annual AQI summary by year
Year
Days with AQI
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Median AQI
90th pct.
Max AQI
Main pollutant
2025
364
302
60
2
0
0
0
34
61
115
Ozone
2024
366
349
17
0
0
0
0
32
45
80
Ozone
2023
365
349
15
1
0
0
0
35
46
120
Ozone
2022
365
313
48
3
0
1
0
42
56
227
Ozone
2021
365
269
96
0
0
0
0
45
64
93
Ozone
2020
365
302
63
0
0
0
0
43
58
93
Ozone
2019
363
331
30
2
0
0
0
31
50
124
Ozone
2018
365
333
32
0
0
0
0
38
50
97
Ozone
2017
360
311
49
0
0
0
0
36
54
93
Ozone
2016
347
343
4
0
0
0
0
17
31
82
PM10
2015
348
342
6
0
0
0
0
17
30
74
PM10
2014
336
335
1
0
0
0
0
17
29
51
PM10
2013
314
305
6
2
1
0
0
17
32
171
PM10
2012
332
326
6
0
0
0
0
19
33
97
PM10
2011
339
333
6
0
0
0
0
17
32
78
PM10
2010
310
298
7
4
1
0
0
17
33
198
PM10
2009
354
341
9
3
1
0
0
19
34
151
PM10
2008
354
348
6
0
0
0
0
19
34
98
PM10
2007
359
356
3
0
0
0
0
19
32
74
PM10
2006
361
360
1
0
0
0
0
19
28
84
PM10
2005
214
207
7
0
0
0
0
21
38
64
PM10
2004
361
352
9
0
0
0
0
22
37
63
PM10
2003
353
342
11
0
0
0
0
23
37
85
PM10
2002
355
341
14
0
0
0
0
21
40
98
PM10
2001
354
324
30
0
0
0
0
23
48
85
PM10
2000
353
330
22
1
0
0
0
24
46
106
PM10
1999
326
313
13
0
0
0
0
23
39
92
PM10
1998
335
327
8
0
0
0
0
23
39
56
PM10
1997
339
313
26
0
0
0
0
23
46
83
PM10
1996
351
317
34
0
0
0
0
26
49
66
PM10
1995
335
305
30
0
0
0
0
27
47
72
PM10
1994
346
269
75
0
2
0
0
33
60
154
PM10
1993
339
260
79
0
0
0
0
36
62
86
PM10
1992
329
243
86
0
0
0
0
37
58
88
PM10
1991
48
31
17
0
0
0
0
20
67
81
PM10
1990
31
29
2
0
0
0
0
19
47
54
PM10
1989
30
21
9
0
0
0
0
36
74
82
PM10
1988
16
11
5
0
0
0
0
50
95
98
PM10
1987
68
54
14
0
0
0
0
31
60
75
PM10
1986
225
140
79
6
0
0
0
41
71
139
PM10
1985
177
105
71
1
0
0
0
43
71
115
PM10
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.
Counties in Colorado with a similar median AQI in 2025
