Marion County, West Virginia air quality history

Daily Air Quality Index summaries from EPA monitors in Marion, West Virginia, 2000–2025.

74%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

120

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Marion, West Virginia on 120 days. 89 of those days (74%) were in the Good range, and the median daily AQI was 37. That median is about the same as the typical monitored county in West Virginia (median 39 across 12 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 120 days. Across the years with fuller monitoring, the share of Good days rose: an average of 34% in 2006–2011 versus 57% in 2012–2025.

EPA did not report an AQI for every day of 2025 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.

Years with fewer than 120 monitored days (2019, 2020, 2021, 2022, 2023, 2024…) 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
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	Unhealthy	Median AQI	90th pct.	Max AQI	Main pollutant
2025	120	89	31	0	0	37	56	71	PM2.5
2024	111	85	26	0	0	33	53	62	PM2.5
2023	118	84	33	0	1	39	58	170	PM2.5
2022	117	91	26	0	0	36	56	73	PM2.5
2021	91	61	30	0	0	40	58	82	PM2.5
2020	74	57	17	0	0	35	55	70	PM2.5
2019	99	70	29	0	0	41	59	66	PM2.5
2018	117	79	38	0	0	38	57	67	PM2.5
2017	114	80	34	0	0	42	57	74	PM2.5
2016	95	57	38	0	0	44	56	65	PM2.5
2015	119	60	59	0	0	49	62	90	PM2.5
2014	119	59	60	0	0	51	62	71	PM2.5
2013	122	64	58	0	0	49	61	78	PM2.5
2012	122	55	67	0	0	52	64	86	PM2.5
2011	121	51	70	0	0	53	68	93	PM2.5
2010	101	31	70	0	0	58	72	99	PM2.5
2009	121	41	80	0	0	55	67	83	PM2.5
2008	116	28	88	0	0	59	73	91	PM2.5
2007	118	26	90	2	0	60	82	111	PM2.5
2006	121	33	87	1	0	60	82	119	PM2.5
2005	118	22	94	2	0	61	84	122	PM2.5
2004	118	27	89	2	0	59	77	137	PM2.5
2003	114	20	92	2	0	61	77	130	PM2.5
2002	114	26	80	7	1	59	82	153	PM2.5
2001	110	24	82	4	0	59	84	141	PM2.5
2000	110	29	78	3	0	61	85	110	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.

Counties in West Virginia with a similar median AQI in 2025

All monitored counties in West Virginia

Source: U.S. EPA AirData, “Annual AQI by County” files for 2000–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem