Daily Air Quality Index summaries from EPA monitors in Matanuska-Susitna, Alaska, 1998–2025.
91%
Good days in 2025
9
Median daily AQI, 2025
2
Days above 100 in 2025
352
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Matanuska-Susitna, Alaska on 352 days. 322 of those days (91%) were in the Good range, and the median daily AQI was 9. That median is lower than the typical monitored county in Alaska (median 26 across 5 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 244 days. Across the years with fuller monitoring, the share of Good days rose: an average of 81% in 1999–2001 versus 91% in 2023–2025.
Years with fewer than 120 monitored days (1998) 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
Fine particles (PM2.5)
244
69%
Coarse particles (PM10)
108
31%
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
352
322
28
2
0
0
0
9
47
141
PM2.5
2024
359
331
28
0
0
0
0
15
43
95
PM2.5
2023
358
317
40
1
0
0
0
14
53
102
PM2.5
2022
341
301
40
0
0
0
0
12
53
89
PM2.5
2021
354
307
44
2
1
0
0
15
54
163
PM2.5
2020
359
317
41
1
0
0
0
17
53
103
PM2.5
2019
361
262
96
3
0
0
0
25
66
127
PM2.5
2018
365
308
53
3
1
0
0
29
58
151
Ozone
2017
365
296
64
4
1
0
0
32
61
157
Ozone
2016
366
282
80
4
0
0
0
34
64
128
Ozone
2015
365
269
85
10
1
0
0
31
78
155
PM2.5
2014
365
254
100
9
1
1
0
33
77
231
PM2.5
2013
365
288
73
4
0
0
0
29
60
114
PM2.5
2012
366
255
106
5
0
0
0
36
73
127
PM2.5
2011
362
261
98
2
0
1
0
38
59
241
PM2.5
2010
317
277
37
3
0
0
0
17
54
118
PM2.5
2009
126
103
22
1
0
0
0
19
61
103
PM2.5
2008
125
102
22
1
0
0
0
20
62
140
PM2.5
2007
132
109
22
1
0
0
0
17
56
107
PM2.5
2006
126
102
20
4
0
0
0
15
61
133
PM2.5
2005
122
93
27
2
0
0
0
27
65
124
PM2.5
2004
121
107
13
0
0
0
1
12
54
501
PM2.5
2003
121
106
14
0
1
0
0
12
56
156
PM2.5
2002
126
108
16
2
0
0
0
23
58
112
PM2.5
2001
125
100
25
0
0
0
0
23
70
93
PM2.5
2000
122
99
22
1
0
0
0
22
63
115
PM2.5
1999
120
97
19
3
1
0
0
18
71
156
PM2.5
1998
89
83
4
1
1
0
0
12
32
164
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 Alaska with a similar median AQI in 2025
