Daily Air Quality Index summaries from EPA monitors in Buchanan, Missouri, 1985–2025.
56%
Good days in 2025
46
Median daily AQI, 2025
2
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Buchanan, Missouri on 365 days. 206 of those days (56%) were in the Good range, and the median daily AQI was 46. That median is higher than the typical monitored county in Missouri (median 41 across 19 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 330 days. Across the years with fuller monitoring, the share of Good days fell: an average of 64% in 1985–1987 versus 57% in 2023–2025.
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, 2025
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)
330
90%
Coarse particles (PM10)
35
10%
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
2025
365
206
157
1
0
1
0
46
62
256
PM2.5
2024
366
219
147
0
0
0
0
44
58
77
PM2.5
2023
363
196
165
2
0
0
0
48
63
129
PM2.5
2022
365
237
126
2
0
0
0
42
58
106
PM2.5
2021
365
235
127
3
0
0
0
44
59
109
PM2.5
2020
365
248
116
1
0
0
0
42
58
126
PM2.5
2019
365
223
142
0
0
0
0
42
61
84
PM2.5
2018
363
201
162
0
0
0
0
47
60
77
PM2.5
2017
365
204
160
1
0
0
0
46
61
109
PM2.5
2016
363
229
134
0
0
0
0
44
58
96
PM2.5
2015
364
179
185
0
0
0
0
51
64
99
PM2.5
2014
363
157
203
3
0
0
0
52
69
141
PM2.5
2013
359
140
219
0
0
0
0
54
69
88
PM2.5
2012
349
145
204
0
0
0
0
53
65
80
PM2.5
2011
261
99
162
0
0
0
0
54
70
97
PM2.5
2010
341
125
216
0
0
0
0
54
72
89
PM2.5
2009
313
107
203
3
0
0
0
56
77
116
PM2.5
2008
317
19
298
0
0
0
0
65
80
95
PM2.5
2007
329
92
236
1
0
0
0
58
75
108
PM2.5
2006
163
49
114
0
0
0
0
54
70
85
PM2.5
2005
121
39
80
2
0
0
0
56
76
107
PM2.5
2004
122
49
73
0
0
0
0
53
67
100
PM2.5
2003
121
44
76
1
0
0
0
54
70
104
PM2.5
2002
122
45
75
2
0
0
0
56
72
120
PM2.5
2001
122
38
84
0
0
0
0
55
75
100
PM2.5
2000
122
43
79
0
0
0
0
56
70
93
PM2.5
1999
181
96
85
0
0
0
0
48
72
91
PM2.5
1998
361
275
86
0
0
0
0
31
62
93
PM10
1997
344
298
46
0
0
0
0
26
52
83
PM10
1996
216
197
18
1
0
0
0
25
48
106
PM10
1995
175
144
31
0
0
0
0
24
57
81
PM10
1994
176
149
27
0
0
0
0
29
54
71
PM10
1993
177
157
20
0
0
0
0
25
51
88
PM10
1992
357
273
84
0
0
0
0
33
58
78
PM10
1991
358
246
112
0
0
0
0
40
63
84
PM10
1990
331
249
82
0
0
0
0
34
59
75
PM10
1989
243
170
73
0
0
0
0
37
62
75
PM10
1988
175
112
62
1
0
0
0
41
62
106
PM10
1987
167
121
46
0
0
0
0
34
59
80
PM10
1986
343
222
121
0
0
0
0
43
64
85
PM10
1985
281
156
125
0
0
0
0
46
67
86
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 Missouri with a similar median AQI in 2025
