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

1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 686 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (80% particle days).

When the bad days come in Greenville

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

What to buy, and what not to

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 7 bad days a year; in 2016 to 2025, 1. The air has improved. The worst recent year was 2016, with 6 bad days on 366 monitored days.

Date	AQI	Main pollutant
2016-11-14	203	PM2.5
2016-11-15	181	PM2.5
2016-11-11	132	PM2.5
2016-11-16	126	PM2.5
2023-07-18	126	PM2.5

The air on a normal day

Across 3,650 monitored days from 2016 to 2025, the air in Greenville County rated Good on 55% of them, less often than the 72% typical of monitored counties, and Moderate on 45%. The median day sat at AQI 48; one day in ten went above 64.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)66%2,403 days
ozone33%1,202 days
nitrogen dioxide1%36 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Over 150	Median AQI	Highest AQI
2025*	365	203	162	0	0	47	93
2024	363	198	165	0	0	48	99
2023	365	167	196	2	0	52	126
2022	365	179	186	0	0	51	97
2021	365	180	184	1	0	51	101
2020	366	234	131	1	0	44	116
2019	365	211	154	0	0	46	97
2018	365	237	128	0	0	44	77
2017	365	195	170	0	0	49	97
2016	366	191	169	6	2	50	203
2015	365	186	177	2	0	49	112
2014	365	192	173	0	0	49	98
2013	365	216	149	0	0	46	93
2012	366	170	195	1	0	52	112
2011	365	126	234	5	0	56	145
2010	365	110	248	7	0	56	122

*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.