Washington County, Arkansas air quality history

Daily Air Quality Index summaries from EPA monitors in Washington, Arkansas, 1989–2025.

83%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

365

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Washington, Arkansas on 365 days. 304 of those days (83%) were in the Good range, and the median daily AQI was 40. That median is lower than the typical monitored county in Arkansas (median 46 across 11 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 294 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 81% in 2007–2009 versus 80% in 2023–2025.

Years with fewer than 120 monitored days (2000, 2001, 2002, 2003, 2004, 2006…) 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, 2025

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	294	81%
Fine particles (PM2.5)	71	19%

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
2025	365	304	61	0	0	40	54	74	Ozone
2024	366	304	61	1	0	41	54	101	Ozone
2023	365	265	95	5	0	44	64	119	Ozone
2022	365	214	148	3	0	47	61	119	PM2.5
2021	365	206	158	1	0	48	66	119	PM2.5
2020	366	251	114	1	0	44	58	150	PM2.5
2019	365	193	172	0	0	48	61	97	PM2.5
2018	365	196	169	0	0	48	67	87	PM2.5
2017	365	174	191	0	0	51	62	83	PM2.5
2016	366	311	55	0	0	40	53	77	Ozone
2015	365	313	52	0	0	38	54	90	Ozone
2014	365	300	65	0	0	41	58	88	Ozone
2013	365	258	107	0	0	44	64	97	Ozone
2012	366	247	102	16	1	44	80	151	Ozone
2011	365	236	124	5	0	45	73	140	Ozone
2010	365	255	109	1	0	42	67	112	Ozone
2009	361	285	74	2	0	39	59	122	Ozone
2008	366	278	88	0	0	38	58	87	Ozone
2007	365	324	39	2	0	35	54	115	Ozone
2006	89	88	1	0	0	30	42	54	Ozone
2004	92	44	48	0	0	51	62	77	PM2.5
2003	113	52	61	0	0	52	64	87	PM2.5
2002	112	46	66	0	0	54	65	90	PM2.5
2001	99	39	60	0	0	55	68	85	PM2.5
2000	96	29	67	0	0	56	72	98	PM2.5
1999	44	14	30	0	0	58	71	91	PM2.5
1997	54	54	0	0	0	19	29	50	PM10
1996	59	58	1	0	0	20	33	52	PM10
1995	58	58	0	0	0	23	33	48	PM10
1994	52	52	0	0	0	21	37	49	PM10
1993	51	49	2	0	0	19	36	53	PM10
1992	60	59	1	0	0	19	30	55	PM10
1991	58	58	0	0	0	19	35	44	PM10
1990	59	57	2	0	0	19	35	53	PM10
1989	36	34	2	0	0	25	34	56	PM10

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 Arkansas with a similar median AQI in 2025

All monitored counties in Arkansas

Source: U.S. EPA AirData, “Annual AQI by County” files for 1989–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem