Daily Air Quality Index summaries from EPA monitors in Henderson, Kentucky, 1980–2019.
52%
Good days in 2018
49
Median daily AQI, 2018
2
Days above 100 in 2018
360
Days with an AQI in 2018 (of 365)
In 2018, EPA reported a daily Air Quality Index (AQI) for Henderson, Kentucky on 360 days. 188 of those days (52%) were in the Good range, and the median daily AQI was 49. That median is higher than the typical monitored county in Kentucky (median 39 across 27 counties), and higher than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 281 days. Across the years with fuller monitoring, the share of Good days fell: an average of 76% in 1980–1982 versus 46% in 2016–2018.
The most recent year with data for this county is 2019; EPA's files for 2020–2025 contain no row for it, which usually means its monitors stopped reporting.
Years with fewer than 120 monitored days (2019) 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, 2018
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)
281
78%
Ozone
79
22%
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
2019
59
29
30
0
0
0
0
53
65
71
PM2.5
2018
360
188
170
2
0
0
0
49
66
108
PM2.5
2017
365
156
208
1
0
0
0
52
64
103
PM2.5
2016
366
158
204
4
0
0
0
52
67
112
PM2.5
2015
365
202
161
2
0
0
0
47
67
101
PM2.5
2014
348
211
137
0
0
0
0
44
67
100
PM2.5
2013
361
222
139
0
0
0
0
45
64
97
PM2.5
2012
366
190
148
24
4
0
0
49
90
164
PM2.5
2011
363
200
154
9
0
0
0
48
70
140
PM2.5
2010
363
170
183
10
0
0
0
52
78
122
PM2.5
2009
361
189
168
4
0
0
0
49
71
108
PM2.5
2008
362
184
170
8
0
0
0
49
74
122
PM2.5
2007
359
198
133
27
1
0
0
48
93
156
Ozone
2006
361
222
128
11
0
0
0
43
77
126
Ozone
2005
361
220
120
21
0
0
0
45
90
147
Ozone
2004
364
250
111
3
0
0
0
41
67
112
Ozone
2003
322
190
115
17
0
0
0
46
84
143
Ozone
2002
324
174
122
23
5
0
0
49
100
197
Ozone
2001
365
228
120
16
1
0
0
44
79
154
Ozone
2000
366
205
138
23
0
0
0
45
82
150
Ozone
1999
365
218
105
33
9
0
0
44
105
185
Ozone
1998
362
258
84
17
3
0
0
39
87
177
Ozone
1997
365
280
70
12
3
0
0
36
74
166
NO2
1996
366
264
77
18
7
0
0
41
90
174
Ozone
1995
365
253
74
30
8
0
0
41
101
182
Ozone
1994
365
267
80
13
5
0
0
39
87
190
Ozone
1993
365
275
76
12
2
0
0
39
77
166
NO2
1992
366
286
69
10
1
0
0
38
67
177
NO2
1991
365
295
66
4
0
0
0
37
63
150
NO2
1990
365
304
54
7
0
0
0
37
58
147
NO2
1989
365
267
94
4
0
0
0
40
70
108
NO2
1988
366
253
80
23
9
1
0
42
97
209
NO2
1987
365
256
97
12
0
0
0
41
73
136
NO2
1986
364
286
66
10
2
0
0
38
71
166
NO2
1985
365
258
94
9
3
1
0
41
74
208
NO2
1984
366
259
99
7
1
0
0
40
70
154
NO2
1983
365
245
88
21
11
0
0
42
93
195
NO2
1982
364
251
108
5
0
0
0
42
74
140
NO2
1981
365
294
67
2
0
2
0
35
61
203
NO2
1980
364
286
65
10
3
0
0
34
71
154
NO2
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.
