Winchester City, Virginia air quality history

Daily Air Quality Index summaries from EPA monitors in Winchester City, Virginia, 1989–2020.

100%

Good days in 2020

Median daily AQI, 2020

Days above 100 in 2020

Days with an AQI in 2020 (of 366)

In 2020, EPA reported a daily Air Quality Index (AQI) for Winchester City, Virginia on 58 days. 58 of those days (100%) were in the Good range, and the median daily AQI was 6. That median is lower than the typical monitored county in Virginia (median 34 across 24 counties), and lower than the typical monitored U.S. county (39). The main pollutant was coarse particles (PM10) on 58 days.

EPA did not report an AQI for every day of 2020 here (58 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 2020; EPA's files for 2021–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2015, 2016, 2017, 2018, 2019, 2020…) 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, 2020

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
Coarse particles (PM10)	58	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Median AQI	90th pct.	Max AQI	Main pollutant
2020	58	58	0	6	12	18	PM10
2019	57	57	0	8	14	24	PM10
2018	60	60	0	8	16	20	PM10
2017	59	59	0	11	17	19	PM10
2016	59	59	0	10	16	25	PM10
2015	59	59	0	11	17	31	PM10
2014	61	61	0	8	14	18	PM10
2013	57	57	0	9	14	19	PM10
2012	60	60	0	14	25	30	PM10
2011	60	60	0	12	19	32	PM10
2010	60	60	0	14	22	40	PM10
2009	57	57	0	16	23	27	PM10
2008	61	61	0	16	25	33	PM10
2007	60	60	0	19	31	47	PM10
2006	61	61	0	16	26	37	PM10
2005	60	60	0	19	30	38	PM10
2004	61	61	0	15	28	44	PM10
2003	61	61	0	16	24	50	PM10
2002	58	58	0	15	26	48	PM10
2001	57	57	0	14	29	47	PM10
2000	59	59	0	17	30	46	PM10
1999	59	59	0	19	32	45	PM10
1998	61	61	0	19	38	48	PM10
1997	59	58	1	19	41	67	PM10
1996	61	61	0	20	33	42	PM10
1995	59	59	0	19	36	46	PM10
1994	60	59	1	18	37	52	PM10
1993	61	60	1	19	39	54	PM10
1992	61	61	0	20	31	37	PM10
1991	60	57	3	25	45	53	PM10
1990	60	59	1	21	42	61	PM10
1989	19	18	1	25	50	53	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.

All monitored counties in Virginia

Source: U.S. EPA AirData, “Annual AQI by County” files for 1989–2020 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem