Daily Air Quality Index summaries from EPA monitors in Washington, Wisconsin, 1980–2010.
91%
Good days in 2010
39
Median daily AQI, 2010
0
Days above 100 in 2010
193
Days with an AQI in 2010 (of 365)
In 2010, EPA reported a daily Air Quality Index (AQI) for Washington, Wisconsin on 193 days. 175 of those days (91%) were in the Good range, and the median daily AQI was 39. That median is about the same as the typical monitored county in Wisconsin (median 40 across 31 counties), and lower than the typical monitored U.S. county (44). The main pollutant was ozone on 193 days. Across the years with fuller monitoring, the share of Good days rose: an average of 68% in 1980–1982 versus 91% in 2008–2010.
EPA did not report an AQI for every day of 2010 here (193 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 2010; EPA's files for 2011–2025 contain no row for it, which usually means its monitors stopped reporting.
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, 2010
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
Ozone
193
100%
Year-by-year data
Annual AQI summary by year
Year
Days with AQI
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Median AQI
90th pct.
Max AQI
Main pollutant
2010
193
175
18
0
0
0
0
39
50
97
Ozone
2009
192
171
20
1
0
0
0
37
51
101
Ozone
2008
188
174
14
0
0
0
0
38
50
71
Ozone
2007
190
158
28
4
0
0
0
39
67
108
Ozone
2006
185
150
35
0
0
0
0
41
64
97
Ozone
2005
185
127
45
13
0
0
0
42
93
140
Ozone
2004
182
154
26
2
0
0
0
38
61
122
Ozone
2003
184
137
37
9
1
0
0
44
87
166
Ozone
2002
179
116
46
13
4
0
0
44
100
179
Ozone
2001
174
132
30
9
3
0
0
42
93
164
Ozone
2000
182
154
22
6
0
0
0
40
71
147
Ozone
1999
162
111
31
15
5
0
0
44
112
177
Ozone
1998
170
115
45
9
1
0
0
46
87
154
Ozone
1997
182
157
20
3
2
0
0
39
64
172
Ozone
1996
184
148
26
8
2
0
0
41
80
192
Ozone
1995
184
126
38
14
5
1
0
44
105
212
Ozone
1994
199
157
31
10
1
0
0
39
74
161
Ozone
1993
208
179
26
3
0
0
0
35
61
119
Ozone
1992
213
175
26
11
1
0
0
35
80
179
Ozone
1991
166
110
37
13
6
0
0
40
112
190
Ozone
1990
210
158
43
7
2
0
0
41
80
166
Ozone
1989
195
128
43
21
1
2
0
45
105
205
Ozone
1988
183
92
41
28
20
2
0
50
154
206
Ozone
1987
183
114
50
11
4
4
0
44
101
216
Ozone
1986
180
128
35
13
4
0
0
41
100
169
Ozone
1985
178
132
32
11
3
0
0
42
93
164
Ozone
1984
172
132
31
8
1
0
0
38
84
164
Ozone
1983
168
105
39
12
12
0
0
44
119
200
Ozone
1982
190
132
40
14
4
0
0
39
100
197
Ozone
1981
121
79
23
10
7
2
0
43
136
206
Ozone
1980
146
103
26
12
4
1
0
38
105
210
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 2010
