Washington County, Vermont air quality history

Daily Air Quality Index summaries from EPA monitors in Washington, Vermont, 1983–2002.

98%

Good days in 1986

Median daily AQI, 1986

Days above 100 in 1986

133

Days with an AQI in 1986 (of 365)

In 1986, EPA reported a daily Air Quality Index (AQI) for Washington, Vermont on 133 days. 130 of those days (98%) were in the Good range, and the median daily AQI was 21. That median is lower than the typical monitored U.S. county (39). The main pollutant was coarse particles (PM10) on 133 days.

EPA did not report an AQI for every day of 1986 here (133 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 2002; EPA's files for 2003–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1997, 1998, 1999, 2000, 2001, 2002…) 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, 1986

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)	133	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
2002	119	63	55	1	48	77	102	PM2.5
2001	116	64	51	1	48	70	109	PM2.5
2000	117	64	52	1	46	69	121	PM2.5
1999	118	60	57	1	49	70	108	PM2.5
1998	58	58	0	0	18	37	48	PM10
1997	56	56	0	0	19	31	36	PM10
1996	56	56	0	0	18	31	36	PM10
1995	58	58	0	0	16	27	43	PM10
1994	57	57	0	0	16	37	46	PM10
1993	56	56	0	0	19	35	44	PM10
1992	51	48	3	0	19	43	54	PM10
1991	53	51	2	0	19	34	62	PM10
1990	51	51	0	0	20	36	45	PM10
1989	48	48	0	0	20	37	48	PM10
1988	56	55	1	0	20	37	56	PM10
1987	105	93	12	0	23	51	61	PM10
1986	133	130	3	0	21	41	70	PM10
1985	91	91	0	0	22	39	46	PM10
1984	49	47	2	0	24	44	53	PM10
1983	47	46	1	0	21	44	77	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 Vermont

Source: U.S. EPA AirData, “Annual AQI by County” files for 1983–2002 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem