Ellis County, Oklahoma air quality history

Daily Air Quality Index summaries from EPA monitors in Ellis, Oklahoma, 2002–2015.

64%

Good days in 2003

Median daily AQI, 2003

Days above 100 in 2003

120

Days with an AQI in 2003 (of 365)

In 2003, EPA reported a daily Air Quality Index (AQI) for Ellis, Oklahoma on 120 days. 77 of those days (64%) were in the Good range, and the median daily AQI was 38. That median is lower than the typical monitored county in Oklahoma (median 43.5 across 20 counties), and lower than the typical monitored U.S. county (44). The main pollutant was fine particles (PM2.5) on 120 days.

EPA did not report an AQI for every day of 2003 here (120 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 2015; EPA's files for 2016–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2010, 2011, 2012, 2013, 2014, 2015…) 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, 2003

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)	120	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
2015	86	75	11	0	31	52	94	PM2.5
2014	116	96	20	0	32	53	62	PM2.5
2013	114	98	16	0	27	54	61	PM2.5
2012	115	100	15	0	33	52	64	PM2.5
2011	118	98	20	0	31	56	87	PM2.5
2010	119	105	14	0	27	52	64	PM2.5
2009	105	94	11	0	24	52	62	PM2.5
2008	118	101	17	0	28	55	63	PM2.5
2007	105	88	17	0	33	54	79	PM2.5
2006	117	101	16	0	27	52	64	PM2.5
2005	118	86	32	0	34	60	75	PM2.5
2004	117	91	26	0	33	56	69	PM2.5
2003	120	77	42	1	38	58	108	PM2.5
2002	88	64	23	1	34	63	117	PM2.5

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 Oklahoma

Source: U.S. EPA AirData, “Annual AQI by County” files for 2002–2015 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem