Bad Air Days in Richland County, Montana: 3 a Year
3 bad air days a year
About the middle of monitored US counties. Ranked 382 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (97% 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 July and September and August. 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 Richland
In 2000 to 2009 this county averaged 0 bad days a year; in 2016 to 2025, 3. It has got worse. The worst recent year was 2023, with 10 bad days on 364 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-05-17 | 219 | PM2.5 |
| 2025-06-11 | 165 | PM2.5 |
| 2023-07-15 | 163 | PM2.5 |
| 2023-09-05 | 159 | PM2.5 |
| 2025-08-10 | 158 | PM2.5 |
The air on a normal day
Across 3,534 monitored days from 2016 to 2025, the air in Richland County rated Good on 84% of them, more often than the 72% typical of monitored counties, and Moderate on 15%. The median day sat at AQI 38; one day in ten went above 56.
The pollutant setting the AQI on an ordinary day here:
- ozone73%2,584 days
- fine particles (PM2.5)26%919 days
- coarse dust (PM10)1%30 days
Richland County by year
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2025* | 273 | 217 | 49 | 7 | 3 | 40 | 165 |
| 2024 | 366 | 307 | 54 | 5 | 0 | 36 | 118 |
| 2023 | 364 | 267 | 87 | 10 | 5 | 39 | 219 |
| 2022 | 361 | 322 | 39 | 0 | 0 | 39 | 79 |
| 2021 | 351 | 284 | 63 | 4 | 0 | 38 | 147 |
| 2020 | 366 | 343 | 23 | 0 | 0 | 37 | 72 |
| 2019 | 365 | 322 | 43 | 0 | 0 | 37 | 93 |
| 2018 | 364 | 298 | 65 | 1 | 0 | 41 | 139 |
| 2017 | 358 | 297 | 59 | 2 | 1 | 39 | 154 |
| 2016 | 366 | 327 | 39 | 0 | 0 | 37 | 99 |
| 2015 | 364 | 298 | 60 | 6 | 3 | 39 | 181 |
| 2014 | 365 | 297 | 67 | 1 | 0 | 37 | 107 |
| 2013 | 365 | 268 | 95 | 2 | 0 | 42 | 110 |
| 2012 | 365 | 228 | 137 | 0 | 0 | 44 | 90 |
| 2011 | 363 | 283 | 80 | 0 | 0 | 38 | 94 |
| 2010 | 365 | 322 | 43 | 0 | 0 | 38 | 84 |
*2025 may be a partial year in EPA's file.
Montana compared
- Missoula County18/yr
- Ravalli County11/yr
- Lewis and Clark County9/yr
- Lincoln County8/yr
- Silver Bow County7/yr
- Sanders County7/yr
- Powder River County6/yr
- Flathead County6/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.