Bad Air Days in Blair County, Pennsylvania: 1 a Year

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 633 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (67% particle days).

Which months to watch

Most bad days here fall in June and July. Averaged over 2016 to 2025.

Is a purifier worth it 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 Blair

In 2000 to 2009 this county averaged 11 bad days a year; in 2016 to 2025, 1. The air has improved. The worst recent year was 2023, with 6 bad days on 358 monitored days.

Date	AQI	Main pollutant
2023-06-29	213	PM2.5
2023-06-28	171	PM2.5
2023-06-07	165	PM2.5
2023-06-30	162	PM2.5
2023-06-08	153	PM2.5

Most days, not the worst ones

Across 3,585 monitored days from 2016 to 2025, the air in Blair County rated Good on 68% of them, less often than the 72% typical of monitored counties, and Moderate on 32%. The median day sat at AQI 43; one day in ten went above 62.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)57%2,027 days
ozone43%1,555 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	363	279	83	1	0	40	115
2024	366	296	70	0	0	37	100
2023	358	229	123	6	5	43	213
2022	363	234	129	0	0	44	97
2021	336	206	128	2	0	45	120
2020	360	262	98	0	0	43	87
2019	352	220	132	0	0	46	93
2018	359	244	114	1	0	42	132
2017	362	223	139	0	0	45	89
2016	366	230	134	2	0	44	122
2015	365	168	195	2	0	52	108
2014	365	151	212	2	0	53	108
2013	365	120	242	3	0	54	115
2012	365	139	212	14	2	54	161
2011	365	146	210	9	1	53	159
2010	365	285	71	9	0	34	147

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

Elsewhere in Pennsylvania

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.