Bad Air Days in Indiana County, Pennsylvania: 2 a Year

2 bad air days a year

Fewer bad air days than most monitored US counties. Ranked 530 of 996 monitored counties, where 1 is worst.

What makes them bad: a mix of particles and ozone (44% particle days).

When the bad days come in Indiana

Most bad days here fall in June and July. 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.

Better or worse than it was

In 2000 to 2009 this county averaged 14 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2023, with 7 bad days on 363 monitored days.

Date	AQI	Main pollutant
2023-06-29	220	PM2.5
2023-06-28	188	PM2.5
2023-06-30	156	PM2.5
2016-07-21	136	Ozone
2023-06-07	127	PM2.5

The air on a normal day

Across 3,556 monitored days from 2016 to 2025, the air in Indiana County rated Good on 82% of them, more often than the 72% typical of monitored counties, and Moderate on 18%. The median day sat at AQI 39; one day in ten went above 55.

The pollutant setting the AQI on an ordinary day here:

ozone70%2,493 days
fine particles (PM2.5)30%1,063 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	273	90	2	0	39	122
2024	357	291	66	0	0	37	74
2023	363	264	92	7	3	41	220
2022	365	264	100	1	0	42	105
2021	348	218	128	2	0	44	122
2020	351	320	30	1	0	37	112
2019	350	324	26	0	0	38	93
2018	355	322	32	1	0	35	105
2017	348	315	33	0	0	38	100
2016	354	309	41	4	0	38	136
2015	363	300	59	4	0	37	119
2014	365	335	28	2	0	38	115
2013	352	305	42	5	1	36	169
2012	355	276	63	16	2	38	156
2011	306	255	44	7	0	39	140
2010	214	133	67	14	1	45	159

*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, and on why a purifier does not touch ozone in smoke vs ozone.