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

under 1 bad air days a year

Rare: among the cleanest-air counties EPA monitors. Ranked 872 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (0% particle days).

Which months to watch

Most bad days here fall in April and June. 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 record for Berkeley

In 2000 to 2009 this county averaged 5 bad days a year; in 2016 to 2025, under 1. The air has improved. The worst recent year was 2023, with 2 bad days on 273 monitored days.

Date	AQI	Main pollutant
2023-06-10	105	Ozone
2023-04-20	101	Ozone
2023-04-19	97	Ozone
2017-05-10	90	Ozone
2024-03-14	90	Ozone

Most days, not the worst ones

Across 2,208 monitored days from 2016 to 2025, the air in Berkeley County rated Good on 95% of them, more often than the 72% typical of monitored counties, and Moderate on 5%. The median day sat at AQI 34; one day in ten went above 47.

The pollutant setting the AQI on an ordinary day here:

ozone100%2,208 days

Year by year

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	270	252	18	0	35	84
2024	278	255	23	0	37	90
2023	273	260	11	2	36	105
2022	234	221	13	0	36	80
2021	258	250	8	0	34	80
2020	220	219	1	0	31	51
2019	79	79	0	0	31	47
2018	152	143	9	0	33	67
2017	248	234	14	0	33	90
2016	196	186	10	0	34	74
2015	211	208	3	0	33	61
2014	212	199	13	0	34	87
2013	234	230	4	0	32	71
2012	205	186	19	0	35	80
2011	264	235	29	0	37	90
2010	323	300	22	1	35	108

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

South Carolina compared

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.