Bad Air Days in Jerome County, Idaho: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 385 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (100% 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 August and September. 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 record for Jerome
The worst recent year was 2017, with 6 bad days on 287 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2017-09-06 | 154 | PM2.5 |
| 2017-09-05 | 146 | PM2.5 |
| 2018-08-24 | 145 | PM2.5 |
| 2018-08-22 | 138 | PM2.5 |
| 2018-08-23 | 134 | PM2.5 |
The air on a normal day
Across 1,372 monitored days from 2016 to 2020, the air in Jerome County rated Good on 92% of them, more often than the 72% typical of monitored counties, and Moderate on 7%. The median day sat at AQI 22; one day in ten went above 43.
The pollutant setting the AQI on an ordinary day here:
- fine particles (PM2.5)100%1,372 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2020 | 213 | 213 | 0 | 0 | 0 | 13 | 49 |
| 2019 | 353 | 345 | 8 | 0 | 0 | 20 | 55 |
| 2018 | 320 | 270 | 45 | 5 | 0 | 24 | 145 |
| 2017 | 287 | 235 | 46 | 6 | 1 | 30 | 154 |
| 2016 | 199 | 198 | 1 | 0 | 0 | 17 | 53 |
| 2015 | 22 | 20 | 2 | 0 | 0 | 16 | 59 |
Nearby counties on file
- Lemhi County15/yr
- Ada County12/yr
- Benewah County10/yr
- Boise County10/yr
- Shoshone County8/yr
- Canyon County7/yr
- Nez Perce County7/yr
- Idaho County7/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.