Sullivan County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Sullivan, Indiana, 1980–2020.

60%

Good days in 2018

Median daily AQI, 2018

Days above 100 in 2018

181

Days with an AQI in 2018 (of 365)

In 2018, EPA reported a daily Air Quality Index (AQI) for Sullivan, Indiana on 181 days. 108 of those days (60%) were in the Good range, and the median daily AQI was 43. That median is higher than the typical monitored county in Indiana (median 38 across 35 counties), and about the same as the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 181 days. Across the years with fuller monitoring, the share of Good days fell: an average of 100% in 1980–1982 versus 74% in 1986–2018.

EPA did not report an AQI for every day of 2018 here (181 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

The most recent year with data for this county is 2020; EPA's files for 2021–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1987, 2019, 2020) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median daily AQI
90th-percentile daily AQI

Main pollutant by day, 2018

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

Pollutant	Days as main pollutant	Share of monitored days
Fine particles (PM2.5)	181	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Median AQI	90th pct.	Max AQI	Main pollutant
2020	31	23	8	0	39	57	59	PM2.5
2019	116	73	43	0	41	58	81	PM2.5
2018	181	108	73	0	43	62	92	PM2.5
2017	264	164	100	0	43	58	69	PM2.5
1987	46	46	0	0	17	29	33	NO2
1986	357	354	3	0	14	27	67	NO2
1985	359	355	4	0	16	27	61	NO2
1984	351	347	4	0	17	29	59	NO2
1983	352	348	2	2	16	29	107	NO2
1982	363	363	0	0	13	25	42	NO2
1981	351	350	1	0	13	24	52	NO2
1980	258	258	0	0	18	27	42	NO2

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

All monitored counties in Indiana

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2020 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem