Daily Air Quality Index summaries from EPA monitors in Clay, Alabama, 1991–2025.
81%
Good days in 2025
33
Median daily AQI, 2025
1
Days above 100 in 2025
354
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Clay, Alabama on 354 days. 287 of those days (81%) were in the Good range, and the median daily AQI was 33. That median is lower than the typical monitored county in Alabama (median 41 across 14 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 354 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1991–1993 versus 78% in 2023–2025.
Years with fewer than 120 monitored days (2017, 2018, 2019, 2020, 2021, 2022…) 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)
354
100%
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
354
287
66
1
0
0
0
33
55
133
PM2.5
2024
354
307
47
0
0
0
0
29
52
75
PM2.5
2023
327
221
106
0
0
0
0
41
61
85
PM2.5
2022
115
91
24
0
0
0
0
34
56
68
PM2.5
2021
110
87
23
0
0
0
0
36
55
70
PM2.5
2020
105
83
22
0
0
0
0
34
56
88
PM2.5
2019
107
75
32
0
0
0
0
41
56
71
PM2.5
2018
110
86
24
0
0
0
0
36
54
68
PM2.5
2017
118
76
42
0
0
0
0
40
57
69
PM2.5
2016
116
83
33
0
0
0
0
41
54
61
PM2.5
2015
112
73
39
0
0
0
0
43
56
92
PM2.5
2014
114
64
50
0
0
0
0
48
59
73
PM2.5
2013
118
79
39
0
0
0
0
42
58
69
PM2.5
2012
121
71
50
0
0
0
0
46
61
75
PM2.5
2011
118
57
61
0
0
0
0
52
67
88
PM2.5
2010
113
46
67
0
0
0
0
53
64
87
PM2.5
2009
119
68
51
0
0
0
0
44
63
95
PM2.5
2008
110
43
67
0
0
0
0
53
66
94
PM2.5
2007
283
120
151
10
2
0
0
54
86
166
Ozone
2006
286
147
130
9
0
0
0
49
82
140
Ozone
2005
282
156
116
10
0
0
0
49
84
136
Ozone
2004
283
167
112
4
0
0
0
47
77
129
Ozone
2003
274
155
109
9
1
0
0
47
77
159
Ozone
2002
277
144
113
17
3
0
0
49
93
166
Ozone
2001
279
145
119
14
1
0
0
49
87
164
Ozone
2000
271
142
114
14
1
0
0
49
90
177
Ozone
1999
273
108
106
49
10
0
0
61
122
182
Ozone
1998
213
99
83
21
10
0
0
54
115
185
Ozone
1997
214
124
70
20
0
0
0
48
100
150
Ozone
1996
242
157
66
17
2
0
0
45
93
161
Ozone
1995
327
223
72
24
8
0
0
42
100
197
Ozone
1994
353
276
64
11
2
0
0
38
74
197
Ozone
1993
306
220
69
16
1
0
0
44
84
164
Ozone
1992
226
215
11
0
0
0
0
25
45
74
Ozone
1991
210
209
1
0
0
0
0
22
34
58
Ozone
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 Alabama with a similar median AQI in 2025
