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

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 675 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 Colleton

Most bad days here fall in November. 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.

The worst days on file

In 2000 to 2009 this county averaged 10 bad days a year; in 2016 to 2025, 1. The air has improved. The worst recent year was 2016, with 3 bad days on 343 monitored days.

Date	AQI	Main pollutant
2016-11-11	153	PM2.5
2016-11-15	136	PM2.5
2016-11-16	126	PM2.5
2017-03-09	84	PM2.5
2016-11-17	82	PM2.5

Most days, not the worst ones

Across 1,066 monitored days from 2016 to 2019, the air in Colleton County rated Good on 78% of them, more often than the 72% typical of monitored counties, and Moderate on 22%. The median day sat at AQI 39; one day in ten went above 56.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)66%708 days
ozone34%358 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2019	7	7	0	0	0	26	41
2018	359	294	65	0	0	36	79
2017	357	263	94	0	0	41	84
2016	343	264	76	3	1	39	153
2015	299	252	47	0	0	37	72
2014	336	233	102	1	1	42	152
2013	334	240	94	0	0	39	100
2012	325	192	133	0	0	46	76
2011	349	175	171	3	1	50	164
2010	345	311	32	2	0	36	108

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.