Bad Air Days in Simpson County, Kentucky: 1 a Year
1 bad air day a year
Fewer bad air days than most monitored US counties. Ranked 636 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (0% 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. Averaged over 2016 to 2025.
Is a purifier worth it here?
- 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 record for Simpson
In 2000 to 2009 this county averaged 22 bad days a year; in 2016 to 2025, 1. The air has improved. The worst recent year was 2023, with 7 bad days on 244 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-06-28 | 122 | Ozone |
| 2023-06-06 | 119 | Ozone |
| 2023-06-10 | 112 | Ozone |
| 2023-06-05 | 108 | Ozone |
| 2023-06-16 | 105 | Ozone |
The air on a normal day
Across 2,401 monitored days from 2016 to 2025, the air in Simpson County rated Good on 90% of them, more often than the 72% typical of monitored counties, and Moderate on 10%. The median day sat at AQI 40; one day in ten went above 52.
The pollutant setting the AQI on an ordinary day here:
- ozone100%2,401 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 243 | 227 | 16 | 0 | 0 | 39 | 74 |
| 2024 | 242 | 204 | 38 | 0 | 0 | 43 | 97 |
| 2023 | 244 | 204 | 33 | 7 | 0 | 43 | 122 |
| 2022 | 241 | 217 | 24 | 0 | 0 | 39 | 93 |
| 2021 | 243 | 222 | 21 | 0 | 0 | 37 | 90 |
| 2020 | 221 | 217 | 4 | 0 | 0 | 36 | 67 |
| 2019 | 244 | 222 | 22 | 0 | 0 | 40 | 67 |
| 2018 | 243 | 212 | 31 | 0 | 0 | 38 | 93 |
| 2017 | 237 | 220 | 17 | 0 | 0 | 40 | 87 |
| 2016 | 243 | 217 | 25 | 1 | 0 | 40 | 101 |
| 2015 | 208 | 179 | 28 | 1 | 0 | 39 | 101 |
| 2014 | 245 | 217 | 28 | 0 | 0 | 39 | 87 |
| 2013 | 235 | 222 | 13 | 0 | 0 | 38 | 67 |
| 2012 | 239 | 192 | 42 | 5 | 0 | 43 | 129 |
| 2011 | 241 | 164 | 72 | 5 | 0 | 45 | 143 |
| 2010 | 243 | 160 | 76 | 7 | 0 | 46 | 112 |
*2025 may be a partial year in EPA's file.
Nearby counties on file
- Jefferson County9/yr
- Oldham County3/yr
- Henderson County2/yr
- Campbell County2/yr
- Boone County2/yr
- Bullitt County2/yr
- McCracken County2/yr
- Daviess 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.