King William County, Virginia air quality history

Daily Air Quality Index summaries from EPA monitors in King William, Virginia, 1990–2016.

100%

Good days in 2016

Median daily AQI, 2016

Days above 100 in 2016

Days with an AQI in 2016 (of 366)

In 2016, EPA reported a daily Air Quality Index (AQI) for King William, Virginia on 29 days. 29 of those days (100%) were in the Good range, and the median daily AQI was 8. That median is lower than the typical monitored county in Virginia (median 38 across 27 counties), and lower than the typical monitored U.S. county (41). The main pollutant was coarse particles (PM10) on 29 days.

EPA did not report an AQI for every day of 2016 here (29 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 2016; EPA's files for 2017–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2011, 2012, 2013, 2014, 2015, 2016…) 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, 2016

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)	29	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Median AQI	90th pct.	Max AQI	Main pollutant
2016	29	29	0	8	14	20	PM10
2015	54	54	0	12	19	30	PM10
2014	57	57	0	10	19	27	PM10
2013	60	60	0	11	18	25	PM10
2012	59	59	0	11	19	28	PM10
2011	55	54	1	12	25	100	PM10
2010	57	57	0	13	27	42	PM10
2009	58	58	0	14	22	32	PM10
2008	59	59	0	16	27	33	PM10
2007	58	58	0	16	28	38	PM10
2006	60	60	0	16	33	48	PM10
2005	56	56	0	19	33	45	PM10
2004	25	25	0	10	18	20	PM10
2003	60	59	1	12	26	55	PM10
2002	56	56	0	14	27	42	PM10
2001	58	58	0	13	30	42	PM10
2000	61	61	0	15	31	40	PM10
1999	59	59	0	14	31	45	PM10
1998	60	60	0	15	33	48	PM10
1997	61	60	1	14	34	59	PM10
1996	60	58	2	15	34	57	PM10
1995	61	61	0	14	32	43	PM10
1994	61	61	0	16	28	41	PM10
1993	58	58	0	18	37	48	PM10
1992	61	61	0	15	30	49	PM10
1991	60	56	4	19	42	57	PM10
1990	60	59	1	20	31	52	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 Virginia with a similar median AQI in 2016

All monitored counties in Virginia

Source: U.S. EPA AirData, “Annual AQI by County” files for 1990–2016 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem