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

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 747 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (71% particle days).

When the bad days come in Chesterfield

Most bad days here fall in March and February and July and September and November. 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.

Better or worse than it was

In 2000 to 2009 this county averaged 12 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2024, with 2 bad days on 364 monitored days.

Date	AQI	Main pollutant
2024-02-17	143	PM2.5
2016-11-16	139	PM2.5
2023-07-18	134	PM2.5
2017-09-28	112	Ozone
2018-03-11	104	PM2.5

Most days, not the worst ones

Across 3,557 monitored days from 2016 to 2025, the air in Chesterfield County rated Good on 74% of them, close to the 72% typical of monitored counties, and Moderate on 26%. The median day sat at AQI 40; one day in ten went above 57.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)61%2,181 days
ozone39%1,370 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	234	130	1	0	44	103
2024	364	234	128	2	0	44	143
2023	365	242	122	1	0	42	134
2022	343	273	70	0	0	40	97
2021	358	268	90	0	0	41	81
2020	346	287	59	0	0	39	91
2019	364	284	80	0	0	34	77
2018	338	266	71	1	0	36	104
2017	358	288	69	1	0	40	112
2016	356	250	105	1	0	42	139
2015	357	218	139	0	0	47	91
2014	351	147	204	0	0	52	80
2013	350	183	167	0	0	49	80
2012	261	185	74	2	1	43	151
2011	299	197	100	2	0	45	108
2010	345	225	117	3	0	44	126

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

Elsewhere in South Carolina

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.