Bad Air Days in Oldham County, Kentucky: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 424 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly ozone: summer smog (0% particle days).
Which months to watch
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in June and August. Averaged over 2016 to 2025.
What actually helps 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 Oldham
In 2000 to 2009 this county averaged 33 bad days a year; in 2016 to 2025, 3. The air has improved. The worst recent year was 2024, with 5 bad days on 242 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2024-07-08 | 136 | Ozone |
| 2024-08-27 | 122 | Ozone |
| 2017-05-15 | 119 | Ozone |
| 2016-05-24 | 112 | Ozone |
| 2022-06-21 | 112 | Ozone |
An ordinary day in Oldham
Across 2,419 monitored days from 2016 to 2025, the air in Oldham County rated Good on 86% of them, more often than the 72% typical of monitored counties, and Moderate on 13%. The median day sat at AQI 40; one day in ten went above 56.
The pollutant setting the AQI on an ordinary day here:
- ozone100%2,419 days
Oldham County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 244 | 214 | 28 | 2 | 0 | 39 | 108 |
| 2024 | 242 | 194 | 43 | 5 | 0 | 43 | 136 |
| 2023 | 242 | 195 | 46 | 1 | 0 | 42 | 105 |
| 2022 | 245 | 221 | 22 | 2 | 0 | 41 | 112 |
| 2021 | 244 | 216 | 27 | 1 | 0 | 39 | 105 |
| 2020 | 239 | 218 | 21 | 0 | 0 | 38 | 97 |
| 2019 | 242 | 203 | 38 | 1 | 0 | 42 | 105 |
| 2018 | 243 | 214 | 28 | 1 | 0 | 38 | 108 |
| 2017 | 237 | 208 | 28 | 1 | 0 | 40 | 119 |
| 2016 | 241 | 204 | 34 | 3 | 0 | 41 | 112 |
| 2015 | 191 | 164 | 23 | 4 | 0 | 39 | 129 |
| 2014 | 245 | 205 | 39 | 1 | 0 | 42 | 101 |
| 2013 | 243 | 209 | 33 | 1 | 0 | 40 | 108 |
| 2012 | 245 | 154 | 69 | 22 | 7 | 47 | 204 |
| 2011 | 245 | 152 | 71 | 22 | 6 | 46 | 179 |
| 2010 | 243 | 138 | 89 | 16 | 1 | 48 | 161 |
*2025 may be a partial year in EPA's file.
Elsewhere in Kentucky
- Jefferson County9/yr
- Henderson County2/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.