Bad Air Days in Carroll County, Indiana: 1 a Year

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 614 of 996 monitored counties, where 1 is worst.

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

When the bad days come in Carroll

Most bad days here fall in May and June. 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.

Better or worse than it was

The worst recent year was 2023, with 5 bad days on 351 monitored days.

Date	AQI	Main pollutant
2023-06-02	122	Ozone
2023-06-03	119	Ozone
2018-05-25	115	Ozone
2023-05-24	115	Ozone
2018-05-27	112	Ozone

The air on a normal day

Across 3,283 monitored days from 2016 to 2025, the air in Carroll County rated Good on 91% of them, more often than the 72% typical of monitored counties, and Moderate on 8%. The median day sat at AQI 35; one day in ten went above 50.

The pollutant setting the AQI on an ordinary day here:

ozone100%3,283 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	347	315	31	1	0	35	105
2024	361	317	44	0	0	36	90
2023	351	308	38	5	0	36	122
2022	364	343	21	0	0	34	93
2021	365	338	26	1	0	34	105
2020	364	352	12	0	0	31	100
2019	358	333	25	0	0	35	84
2018	359	337	19	3	0	32	115
2017	232	210	22	0	0	39	77
2016	182	147	33	2	0	39	101
2015	183	155	28	0	0	43	87
2014	173	144	28	1	0	41	108
2013	176	139	37	0	0	43	97
2012	182	122	50	10	1	47	156
2011	171	147	23	1	0	40	122
2010	182	139	39	4	0	45	119

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

Indiana compared

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.