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

under 1 bad air days a year

Rare: among the cleanest-air counties EPA monitors. Ranked 862 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (33% particle days).

Which months to watch

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

Is a purifier worth it 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.

Better or worse than it was

In 2000 to 2009 this county averaged 21 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2016, with 1 bad day on 265 monitored days.

Date	AQI	Main pollutant
2023-06-29	139	PM2.5
2016-04-19	115	Ozone
2021-05-20	101	Ozone
2023-06-08	99	PM2.5
2021-08-25	97	Ozone

Most days, not the worst ones

Across 2,949 monitored days from 2016 to 2025, the air in Chesterfield County rated Good on 85% of them, more often than the 72% typical of monitored counties, and Moderate on 15%. The median day sat at AQI 39; one day in ten went above 53.

The pollutant setting the AQI on an ordinary day here:

ozone63%1,851 days
fine particles (PM2.5)37%1,094 days

Chesterfield County by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	364	294	70	0	0	39	80
2024	361	273	88	0	0	41	77
2023	278	242	35	1	0	41	139
2022	286	264	22	0	0	38	80
2021	283	243	39	1	0	38	101
2020	279	265	14	0	0	34	61
2019	280	235	45	0	0	40	87
2018	275	238	37	0	0	36	77
2017	278	236	42	0	0	40	77
2016	265	212	52	1	0	39	115
2015	247	186	61	0	0	41	100
2014	241	187	54	0	0	41	90
2013	260	207	53	0	0	39	87
2012	259	182	71	6	0	44	133
2011	254	167	82	5	0	44	126
2010	258	149	102	7	3	48	182

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

Elsewhere in Virginia

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.