Bad Air Days in Madison County, Indiana: 3 a Year

3 bad air days a year

About the middle of monitored US counties. Ranked 408 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (33% particle days).

The bad-air season here

Most bad days here fall in June and May and July. 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 Madison

In 2000 to 2009 this county averaged 21 bad days a year; in 2016 to 2025, 3. The air has improved. The worst recent year was 2023, with 12 bad days on 365 monitored days.

Date	AQI	Main pollutant
2023-06-27	229	PM2.5
2023-06-28	193	PM2.5
2023-06-29	142	PM2.5
2018-05-25	136	Ozone
2022-06-20	133	Ozone

The air on a normal day

Across 3,643 monitored days from 2016 to 2025, the air in Madison County rated Good on 61% of them, less often than the 72% typical of monitored counties, and Moderate on 38%. The median day sat at AQI 46; one day in ten went above 63.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)61%2,227 days
ozone39%1,416 days

Madison County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	260	103	2	0	41	122
2024	365	263	102	0	0	42	97
2023	365	203	150	12	2	48	229
2022	365	224	137	4	0	45	133
2021	364	199	165	0	0	48	97
2020	366	233	133	0	0	44	97
2019	365	216	148	1	0	47	101
2018	365	199	159	7	0	48	136
2017	365	201	163	1	0	48	105
2016	358	224	134	0	0	44	97
2015	363	202	161	0	0	45	89
2014	335	151	182	2	0	52	141
2013	363	156	206	1	0	52	118
2012	352	146	196	10	1	53	151
2011	318	134	178	6	0	54	112
2010	290	136	154	0	0	53	100

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

Elsewhere in Indiana

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.