Bad Air Days in Spencer County, Indiana

Not enough data

EPA monitors in Spencer County ran on too few days between 2016 and 2025 to give a fair yearly count (about 41% of days covered). Neighbouring counties below are a better guide.

What actually helps here

EPA monitors here ran too few days to give a fair yearly count. Use AirNow for today's air.

The record for Spencer

The worst recent year was 2023, with 1 bad day on 120 monitored days.

Date	AQI	Main pollutant
2023-10-30	170	PM2.5
2021-07-21	89	PM2.5
2025-01-09	88	PM2.5
2018-02-10	87	PM2.5
2023-06-08	86	PM2.5

The air on a normal day

Across 1,481 monitored days from 2016 to 2025, the air in Spencer County rated Good on 67% of them, less often than the 72% typical of monitored counties, and Moderate on 33%. The median day sat at AQI 40; one day in ten went above 59.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)100%1,481 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	246	119	0	0	39	88
2024	169	132	37	0	0	34	68
2023	120	80	39	1	1	43	170
2022	111	75	36	0	0	42	79
2021	120	78	42	0	0	42	89
2020	122	80	42	0	0	42	67
2019	117	81	36	0	0	41	76
2018	121	72	49	0	0	41	87
2017	118	79	39	0	0	43	71
2016	118	74	44	0	0	43	80
2015	115	63	52	0	0	45	78
2014	121	56	65	0	0	52	96
2013	118	52	66	0	0	52	77
2012	117	54	63	0	0	52	74
2011	113	37	76	0	0	55	93
2010	116	31	85	0	0	57	88

*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.