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

2 bad air days a year

About the middle of monitored US counties. Ranked 477 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (18% particle days).

When the bad days come in Vanderburgh

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.

Better or worse than it was

In 2000 to 2009 this county averaged 23 bad days a year; in 2016 to 2025, 2. The air has improved. The worst recent year was 2023, with 8 bad days on 365 monitored days.

Date	AQI	Main pollutant
2023-06-28	179	PM2.5
2018-07-13	143	Ozone
2016-06-10	140	Ozone
2016-06-25	140	Ozone
2023-06-06	126	Ozone

The air on a normal day

Across 3,651 monitored days from 2016 to 2025, the air in Vanderburgh County rated Good on 56% of them, less often than the 72% typical of monitored counties, and Moderate on 44%. The median day sat at AQI 48; one day in ten went above 64.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)64%2,349 days
ozone36%1,297 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	217	148	0	0	47	100
2024	366	227	137	2	0	46	119
2023	365	152	205	8	1	52	179
2022	365	172	193	0	0	51	100
2021	365	176	188	1	0	51	109
2020	366	248	116	2	0	43	101
2019	365	229	136	0	0	46	90
2018	365	200	162	3	0	48	143
2017	365	205	158	2	0	47	115
2016	364	202	158	4	0	47	140
2015	365	142	217	6	0	53	133
2014	365	116	245	4	0	56	108
2013	365	126	236	3	0	55	108
2012	366	102	242	22	2	57	161
2011	365	162	192	11	0	53	150
2010	365	76	281	8	0	61	122

*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.