Bad Air Days in Henderson County, Kentucky: 2 a Year
2 bad air days a year
About the middle of monitored US counties. Ranked 470 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (14% particle days).
The bad-air season here
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and July. Averaged over 2016 to 2025.
What to buy, and what not to
- Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
- On the odd bad day, check AirNow and keep windows shut.
The worst days on file
In 2000 to 2009 this county averaged 16 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2016, with 4 bad days on 366 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2016-06-10 | 112 | Ozone |
| 2016-06-13 | 108 | Ozone |
| 2018-06-07 | 108 | Ozone |
| 2016-06-11 | 105 | Ozone |
| 2016-06-25 | 105 | Ozone |
The air on a normal day
Across 1,150 monitored days from 2016 to 2019, the air in Henderson County rated Good on 46% of them, less often than the 72% typical of monitored counties, and Moderate on 53%. The median day sat at AQI 51; one day in ten went above 66.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)82%947 days
- ozone18%203 days
Henderson County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2019 | 59 | 29 | 30 | 0 | 0 | 53 | 71 |
| 2018 | 360 | 188 | 170 | 2 | 0 | 49 | 108 |
| 2017 | 365 | 156 | 208 | 1 | 0 | 52 | 103 |
| 2016 | 366 | 158 | 204 | 4 | 0 | 52 | 112 |
| 2015 | 365 | 202 | 161 | 2 | 0 | 47 | 101 |
| 2014 | 348 | 211 | 137 | 0 | 0 | 44 | 100 |
| 2013 | 361 | 222 | 139 | 0 | 0 | 45 | 97 |
| 2012 | 366 | 190 | 148 | 28 | 4 | 49 | 164 |
| 2011 | 363 | 200 | 154 | 9 | 0 | 48 | 140 |
| 2010 | 363 | 170 | 183 | 10 | 0 | 52 | 122 |
Nearby counties on file
- Jefferson County9/yr
- Oldham County3/yr
- Campbell County2/yr
- Boone County2/yr
- Bullitt County2/yr
- McCracken County2/yr
- Daviess County2/yr
- Hancock County2/yr
How this is counted
A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day, and on why a purifier does not touch ozone in smoke vs ozone.