Madison County, Mississippi air quality history

Daily Air Quality Index summaries from EPA monitors in Madison, Mississippi, 1980–2004.

81%

Good days in 2004

Median daily AQI, 2004

Days above 100 in 2004

226

Days with an AQI in 2004 (of 366)

In 2004, EPA reported a daily Air Quality Index (AQI) for Madison, Mississippi on 226 days. 182 of those days (81%) were in the Good range, and the median daily AQI was 41. That median is lower than the typical monitored county in Mississippi (median 46.5 across 14 counties), and about the same as the typical monitored U.S. county (42). The main pollutant was ozone on 226 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 77% in 1980–1982 versus 78% in 2002–2004.

EPA did not report an AQI for every day of 2004 here (226 of 366 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 2004; EPA's files for 2005–2025 contain no row for it, which usually means its monitors stopped reporting.

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	226	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Unhealthy	Very Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2004	226	182	39	5	0	0	41	71	140	Ozone
2003	240	178	54	8	0	0	42	74	133	Ozone
2002	236	189	40	6	1	0	40	71	156	Ozone
2001	245	167	63	15	0	0	44	90	122	Ozone
2000	244	119	98	27	0	0	51	105	140	Ozone
1999	214	118	73	22	1	0	49	101	177	Ozone
1998	210	115	69	22	4	0	48	108	185	Ozone
1997	208	122	76	10	0	0	48	90	140	Ozone
1996	270	189	65	16	0	0	43	87	143	Ozone
1995	269	182	76	11	0	0	44	84	136	Ozone
1994	262	197	56	9	0	0	41	77	147	Ozone
1993	270	218	44	8	0	0	42	64	147	Ozone
1992	264	208	46	10	0	0	42	74	126	Ozone
1991	246	202	39	5	0	0	39	61	140	Ozone
1990	271	182	66	23	0	0	44	97	150	Ozone
1989	263	213	44	5	1	0	37	67	159	Ozone
1988	251	171	57	22	1	0	44	100	154	Ozone
1982	201	169	24	5	1	2	38	64	203	Ozone
1981	249	178	58	13	0	0	43	84	147	Ozone
1980	287	216	42	26	2	1	36	101	205	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.

Counties in Mississippi with a similar median AQI in 2004

All monitored counties in Mississippi

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2004 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem