Bad Air Days in Buchanan County, Missouri: 1 a Year

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 656 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (100% particle days).

When the bad days come in Buchanan

Most bad days here fall in July and August and September. Averaged over 2016 to 2025.

What to buy, and what not to

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

The worst days on file

In 2000 to 2009 this county averaged 2 bad days a year; in 2016 to 2025, 1. Not much has changed. The worst recent year was 2021, with 3 bad days on 365 monitored days.

Date	AQI	Main pollutant
2025-03-14	256	PM10
2025-08-01	131	PM2.5
2023-09-07	129	PM2.5
2020-07-04	126	PM2.5
2023-09-06	118	PM2.5

Most days, not the worst ones

Across 3,645 monitored days from 2016 to 2025, the air in Buchanan County rated Good on 60% of them, less often than the 72% typical of monitored counties, and Moderate on 39%. The median day sat at AQI 44; one day in ten went above 60.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)90%3,270 days
coarse dust (PM10)10%375 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	206	157	2	1	46	256
2024	366	219	147	0	0	44	77
2023	363	196	165	2	0	48	129
2022	365	237	126	2	0	42	106
2021	365	235	127	3	0	44	109
2020	365	248	116	1	0	42	126
2019	365	223	142	0	0	42	84
2018	363	201	162	0	0	47	77
2017	365	204	160	1	0	46	109
2016	363	229	134	0	0	44	96
2015	364	179	185	0	0	51	99
2014	363	157	203	3	0	52	141
2013	359	140	219	0	0	54	88
2012	349	145	204	0	0	53	80
2011	261	99	162	0	0	54	97
2010	341	125	216	0	0	54	89

*2025 may be a partial year in EPA's file.

Nearby counties on file

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day.