Douglas County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Douglas, Wisconsin, 1980–2005.

75%

Good days in 2002

Median daily AQI, 2002

Days above 100 in 2002

122

Days with an AQI in 2002 (of 365)

In 2002, EPA reported a daily Air Quality Index (AQI) for Douglas, Wisconsin on 122 days. 91 of those days (75%) were in the Good range, and the median daily AQI was 38. That median is lower than the typical monitored county in Wisconsin (median 43 across 31 counties), and lower than the typical monitored U.S. county (44). The main pollutant was fine particles (PM2.5) on 119 days. Across the years with fuller monitoring, the share of Good days fell: an average of 95% in 1980–1982 versus 70% in 2000–2002.

EPA did not report an AQI for every day of 2002 here (122 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 2005; EPA's files for 2006–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1996, 1997, 1998, 2003, 2004, 2005…) 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, 2002

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)	119	98%
Coarse particles (PM10)	3	2%

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
2005	51	51	0	0	19	33	49	PM10
2004	59	59	0	0	16	29	44	PM10
2003	70	60	10	0	20	57	72	PM10
2002	122	91	31	0	38	58	89	PM2.5
2001	122	84	38	0	41	61	82	PM2.5
2000	122	83	39	0	37	61	90	PM2.5
1999	122	86	36	0	39	62	90	PM2.5
1998	61	61	0	0	19	31	50	PM10
1997	62	61	1	0	19	33	59	PM10
1996	65	65	0	0	19	31	45	PM10
1995	62	61	1	0	19	32	56	PM10
1994	61	60	1	0	19	29	67	PM10
1993	62	61	1	0	20	33	51	PM10
1992	65	63	2	0	21	34	55	PM10
1991	62	59	3	0	26	42	60	PM10
1990	160	155	5	0	20	39	64	PM10
1989	181	171	10	0	21	40	76	PM10
1988	285	275	9	1	22	41	133	PM10
1987	56	47	9	0	28	59	87	PM10
1986	87	83	4	0	22	44	59	PM10
1985	154	147	7	0	22	43	62	PM10
1983	195	175	17	3	36	51	140	Ozone
1982	190	184	4	2	29	44	122	Ozone
1981	169	157	10	2	31	45	112	Ozone
1980	162	152	7	3	28	44	129	Ozone

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 Wisconsin with a similar median AQI in 2002

Wood

All monitored counties in Wisconsin

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2005 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem