Bad Air Days in Powder River County, Montana: 6 a Year
6 bad air days a year
More bad air days than three quarters of monitored counties. Ranked 172 of 996 monitored counties, where 1 is worst.
What makes them bad: mostly particles: smoke and dust (88% particle days).
When the bad days come in Powder River
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Most bad days here fall in September and August and July. Averaged over 2016 to 2025.
What to buy, and what not to
- Particles (wildfire smoke, dust) cause enough bad days here to matter. A HEPA purifier sized to your bedroom removes them; run it with windows shut on bad days.
- Upgrade the furnace or AC filter to MERV 13 so the whole house is filtered, not just one room.
Better or worse than it was
The worst recent year was 2021, with 15 bad days on 358 monitored days.
| Date | AQI | Main pollutant |
|---|---|---|
| 2023-05-17 | 195 | PM2.5 |
| 2023-09-05 | 189 | PM2.5 |
| 2017-09-13 | 177 | PM2.5 |
| 2021-07-22 | 169 | Ozone |
| 2017-09-03 | 162 | PM2.5 |
The air on a normal day
Across 2,875 monitored days from 2016 to 2023, the air in Powder River County rated Good on 75% of them, close to the 72% typical of monitored counties, and Moderate on 24%. The median day sat at AQI 41; one day in ten went above 66.
The pollutant setting the AQI on an ordinary day here:
- ozone62%1,778 days
- fine particles (PM2.5)32%931 days
- coarse dust (PM10)6%164 days
Every recent year on file
| Year | Days monitored | Good | Moderate | Over 100 | Over 150 | Median AQI | Highest AQI |
|---|---|---|---|---|---|---|---|
| 2023 | 355 | 244 | 99 | 12 | 6 | 44 | 195 |
| 2022 | 365 | 292 | 70 | 3 | 0 | 39 | 108 |
| 2021 | 358 | 230 | 113 | 15 | 4 | 42 | 169 |
| 2020 | 350 | 254 | 91 | 5 | 2 | 41 | 159 |
| 2019 | 361 | 312 | 48 | 1 | 0 | 38 | 145 |
| 2018 | 362 | 272 | 86 | 4 | 0 | 41 | 117 |
| 2017 | 358 | 243 | 106 | 9 | 5 | 42 | 177 |
| 2016 | 366 | 299 | 67 | 0 | 0 | 39 | 100 |
| 2015 | 358 | 274 | 78 | 6 | 1 | 40 | 170 |
| 2014 | 347 | 286 | 60 | 1 | 0 | 38 | 110 |
| 2013 | 363 | 299 | 64 | 0 | 0 | 39 | 73 |
| 2012 | 358 | 236 | 122 | 0 | 0 | 43 | 94 |
| 2011 | 364 | 273 | 91 | 0 | 0 | 42 | 97 |
| 2010 | 364 | 308 | 56 | 0 | 0 | 39 | 80 |
Nearby counties on file
- Missoula County18/yr
- Ravalli County11/yr
- Lewis and Clark County9/yr
- Lincoln County8/yr
- Silver Bow County7/yr
- Sanders County7/yr
- Flathead County6/yr
- Lake Countythin data
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.