Gibson County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Gibson, Indiana, 1999–2011.

85%

Good days in 2004

Median daily AQI, 2004

Days above 100 in 2004

363

Days with an AQI in 2004 (of 366)

In 2004, EPA reported a daily Air Quality Index (AQI) for Gibson, Indiana on 363 days. 310 of those days (85%) were in the Good range, and the median daily AQI was 31. That median is lower than the typical monitored county in Indiana (median 46 across 31 counties), and lower than the typical monitored U.S. county (42). The main pollutant was ozone on 182 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1999–2001 versus 86% in 2002–2004.

The most recent year with data for this county is 2011; EPA's files for 2012–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2008, 2009, 2010, 2011) 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, 2004

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
Ozone	182	50%
Nitrogen dioxide (NO₂)	181	50%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2011	116	44	72	0	0	53	67	88	PM2.5
2010	119	42	77	0	0	56	71	86	PM2.5
2009	118	46	72	0	0	54	65	85	PM2.5
2008	91	37	54	0	0	53	71	85	PM2.5
2004	363	310	46	7	0	31	61	140	Ozone
2003	355	299	48	7	1	30	67	161	Ozone
2002	365	322	30	13	0	29	58	143	NO2
2001	364	330	33	1	0	30	50	112	NO2
2000	366	344	20	2	0	27	44	112	NO2
1999	270	224	37	7	2	33	67	161	Ozone

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 1999–2011 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem