Bad Air Days in Roosevelt County, Montana

Not enough data

EPA monitors in Roosevelt County ran on too few days between 2016 and 2025 to give a fair yearly count (about 26% of days covered). Neighbouring counties below are a better guide.

Is a purifier worth it here?

EPA monitors here ran too few days to give a fair yearly count. Use AirNow for today's air.

Better or worse than it was

The worst recent year was 2018, with 2 bad days on 105 monitored days.

Date	AQI	Main pollutant
2025-07-12	196	PM2.5
2023-07-14	161	PM2.5
2018-08-18	134	PM2.5
2018-05-08	109	PM2.5
2024-07-23	109	PM2.5

An ordinary day in Roosevelt

Across 934 monitored days from 2016 to 2025, the air in Roosevelt 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 14; one day in ten went above 42.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%934 days

Roosevelt County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	94	82	11	1	1	16	196
2024	98	87	10	1	0	13	109
2023	72	62	9	1	1	13	161
2022	101	98	3	0	0	14	64
2021	100	89	11	0	0	16	99
2020	77	74	3	0	0	12	60
2019	93	89	4	0	0	13	54
2018	105	93	10	2	0	17	134
2017	90	85	5	0	0	15	76
2016	104	100	4	0	0	13	80
2015	102	95	3	4	1	14	153
2014	109	105	4	0	0	15	74
2013	106	103	3	0	0	17	58
2012	103	99	4	0	0	18	54
2011	103	99	4	0	0	17	64
2010	97	90	7	0	0	20	75

*2025 may be a partial year in EPA's file.

Elsewhere in Montana

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.