Bad Air Days in Madison County, Virginia: under 1 a Year

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 744 of 996 monitored counties, where 1 is worst.

What makes them bad: a mix of particles and ozone (57% particle days).

Which months to watch

Most bad days here fall in June and April and July. Averaged over 2016 to 2025.

What actually helps here

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 18 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2023, with 6 bad days on 330 monitored days.

Date	AQI	Main pollutant
2023-06-29	157	PM2.5
2023-06-08	151	PM2.5
2023-06-01	122	Ozone
2023-06-02	115	Ozone
2016-04-19	108	Ozone

An ordinary day in Madison

Across 3,538 monitored days from 2016 to 2025, the air in Madison County rated Good on 88% of them, more often than the 72% typical of monitored counties, and Moderate on 12%. The median day sat at AQI 40; one day in ten went above 53.

The pollutant setting the AQI on an ordinary day here:

ozone87%3,073 days
fine particles (PM2.5)13%464 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	330	283	47	0	0	40	87
2024	351	313	38	0	0	41	90
2023	330	279	45	6	2	42	157
2022	358	323	35	0	0	40	93
2021	365	313	52	0	0	39	89
2020	363	351	12	0	0	37	55
2019	362	326	36	0	0	41	67
2018	356	304	52	0	0	39	90
2017	362	313	49	0	0	41	84
2016	361	302	58	1	0	41	108
2015	361	280	81	0	0	44	89
2014	360	291	69	0	0	43	80
2013	357	298	59	0	0	42	80
2012	352	249	97	6	0	44	140
2011	360	213	142	5	0	47	119
2010	318	211	99	8	0	44	140

*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, and on why a purifier does not touch ozone in smoke vs ozone.