Daily Air Quality Index summaries from EPA monitors in Cobb, Georgia, 1999–2025.
93%
Good days in 2025
35
Median daily AQI, 2025
0
Days above 100 in 2025
245
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Cobb, Georgia on 245 days. 229 of those days (93%) were in the Good range, and the median daily AQI was 35. That median is lower than the typical monitored county in Georgia (median 46 across 25 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 239 days. Across the years with fuller monitoring, the share of Good days rose: an average of 37% in 1999–2001 versus 72% in 2023–2025.
EPA did not report an AQI for every day of 2025 here (245 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.
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
239
98%
Fine particles (PM2.5)
6
2%
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
245
229
16
0
0
0
0
35
47
74
Ozone
2024
364
202
162
0
0
0
0
48
64
86
PM2.5
2023
323
215
105
3
0
0
0
43
65
125
Ozone
2022
285
231
53
1
0
0
0
40
57
105
Ozone
2021
285
218
67
0
0
0
0
41
57
80
Ozone
2020
285
243
42
0
0
0
0
36
54
91
Ozone
2019
282
191
90
1
0
0
0
44
61
119
Ozone
2018
286
213
73
0
0
0
0
41
61
100
Ozone
2017
284
211
73
0
0
0
0
43
58
97
Ozone
2016
351
177
170
3
1
0
0
50
67
200
PM2.5
2015
359
182
176
1
0
0
0
50
62
112
PM2.5
2014
307
136
169
2
0
0
0
52
65
119
PM2.5
2013
355
180
173
2
0
0
0
50
66
108
PM2.5
2012
360
147
204
8
1
0
0
53
70
154
PM2.5
2011
317
105
195
17
0
0
0
55
87
140
PM2.5
2010
347
107
223
16
1
0
0
56
84
156
PM2.5
2009
361
131
225
3
2
0
0
54
71
164
PM2.5
2008
323
120
191
11
1
0
0
55
80
155
PM2.5
2007
283
100
148
30
5
0
0
60
105
172
Ozone
2006
289
111
136
33
8
1
0
59
112
203
Ozone
2005
286
116
143
26
1
0
0
56
100
154
Ozone
2004
286
147
131
8
0
0
0
50
82
129
Ozone
2003
285
128
139
15
2
1
0
53
93
203
Ozone
2002
282
124
115
32
9
2
0
54
122
207
Ozone
2001
277
120
122
29
6
0
0
58
108
174
Ozone
2000
279
113
112
35
15
4
0
60
136
205
Ozone
1999
130
37
75
10
8
0
0
67
126
192
PM2.5
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 Georgia with a similar median AQI in 2025
