Bad Air Days in Perry County, Indiana: under 1 a Year

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 711 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (0% particle days).

Which months to watch

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

What actually helps 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 Perry

The worst recent year was 2016, with 3 bad days on 183 monitored days.

Date	AQI	Main pollutant
2016-06-25	136	Ozone
2016-06-11	126	Ozone
2022-06-21	119	Ozone
2023-06-24	112	Ozone
2016-05-23	108	Ozone

Most days, not the worst ones

Across 3,232 monitored days from 2016 to 2025, the air in Perry County rated Good on 91% of them, more often than the 72% typical of monitored counties, and Moderate on 9%. The median day sat at AQI 37; one day in ten went above 51.

The pollutant setting the AQI on an ordinary day here:

ozone100%3,232 days

Perry County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	317	294	23	0	0	36	84
2024	330	286	44	0	0	39	90
2023	357	318	37	2	0	38	112
2022	365	344	20	1	0	36	119
2021	363	334	29	0	0	36	97
2020	366	352	13	1	0	34	105
2019	358	322	36	0	0	37	80
2018	350	324	26	0	0	35	80
2017	243	212	30	1	0	40	101
2016	183	140	40	3	0	41	136
2015	183	147	34	2	0	43	112
2014	175	131	43	1	0	45	101
2013	183	151	32	0	0	42	100
2012	183	96	66	21	2	49	166
2011	182	129	44	9	0	45	133
2010	183	110	67	6	0	48	122

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

Nearby counties on file

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.