Warren County, Mississippi air quality history

Daily Air Quality Index summaries from EPA monitors in Warren, Mississippi, 1987–2005.

50%

Good days in 2004

Median daily AQI, 2004

Days above 100 in 2004

167

Days with an AQI in 2004 (of 366)

In 2004, EPA reported a daily Air Quality Index (AQI) for Warren, Mississippi on 167 days. 83 of those days (50%) were in the Good range, and the median daily AQI was 51. That median is higher than the typical monitored county in Mississippi (median 46.5 across 14 counties), and higher than the typical monitored U.S. county (42). The main pollutant was fine particles (PM2.5) on 101 days. Across the years with fuller monitoring, the share of Good days fell: an average of 66% in 1987–1989 versus 59% in 2002–2004.

EPA did not report an AQI for every day of 2004 here (167 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 2005; EPA's files for 2006–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2005) 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
Fine particles (PM2.5)	101	60%
Ozone	66	40%

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
2005	109	35	71	3	0	0	55	74	137	PM2.5
2004	167	83	84	0	0	0	51	67	98	PM2.5
2003	268	167	97	4	0	0	45	72	126	Ozone
2002	281	179	95	7	0	0	43	66	146	Ozone
2001	277	164	94	19	0	0	46	93	136	Ozone
2000	279	123	131	24	1	0	53	100	156	Ozone
1999	240	109	116	15	0	0	54	93	136	Ozone
1998	236	164	60	9	3	0	42	93	159	Ozone
1997	236	153	72	11	0	0	45	90	133	Ozone
1996	280	222	48	10	0	0	37	71	150	Ozone
1995	289	205	67	17	0	0	41	87	126	Ozone
1994	289	224	56	7	2	0	39	77	159	Ozone
1993	289	225	59	5	0	0	39	71	133	Ozone
1992	285	245	34	6	0	0	40	61	112	Ozone
1991	279	223	50	6	0	0	38	71	140	Ozone
1990	271	200	56	14	1	0	42	87	164	Ozone
1989	271	197	60	13	0	1	42	80	207	Ozone
1988	267	153	62	46	6	0	47	126	195	Ozone
1987	265	180	74	10	1	0	43	87	154	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 1987–2005 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem