Florence County, South Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Florence, South Carolina, 1999–2025.

65%

Good days in 2025

Median daily AQI, 2025

Days above 100 in 2025

361

Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Florence, South Carolina on 361 days. 235 of those days (65%) were in the Good range, and the median daily AQI was 44. That median is about the same as the typical monitored county in South Carolina (median 43 across 13 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 361 days. Across the years with fuller monitoring, the share of Good days rose: an average of 44% in 2013–2015 versus 61% in 2023–2025.

Years with fewer than 120 monitored days (2007, 2008, 2009, 2010, 2011, 2012…) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median daily AQI
90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

Pollutant	Days as main pollutant	Share of monitored days
Fine particles (PM2.5)	361	100%

Year-by-year data

Annual AQI summary by year
Year	Days with AQI	Good	Moderate	Unhealthy for Sensitive Groups	Median AQI	90th pct.	Max AQI	Main pollutant
2025	361	235	125	1	44	58	108	PM2.5
2024	359	230	129	0	44	59	99	PM2.5
2023	364	191	172	1	49	64	104	PM2.5
2022	333	210	123	0	44	59	79	PM2.5
2021	337	251	86	0	39	58	86	PM2.5
2020	352	290	62	0	37	53	95	PM2.5
2019	361	243	118	0	41	57	73	PM2.5
2018	359	270	89	0	39	57	76	PM2.5
2017	273	197	76	0	38	56	71	PM2.5
2016	232	158	74	0	41	57	85	PM2.5
2015	168	88	80	0	49	60	77	PM2.5
2014	220	81	139	0	54	63	85	PM2.5
2013	219	94	125	0	52	66	77	PM2.5
2012	110	58	52	0	49	61	80	PM2.5
2011	116	50	66	0	54	69	89	PM2.5
2010	110	45	65	0	53	66	91	PM2.5
2009	116	50	66	0	52	64	75	PM2.5
2008	115	42	73	0	55	67	80	PM2.5
2007	113	39	73	1	55	71	117	PM2.5
2006	106	31	75	0	57	75	96	PM2.5
2005	112	37	73	2	55	77	105	PM2.5
2004	112	38	74	0	57	72	95	PM2.5
2003	118	40	78	0	55	71	92	PM2.5
2002	110	43	67	0	54	72	93	PM2.5
2001	108	32	76	0	57	73	84	PM2.5
2000	114	28	85	1	59	79	130	PM2.5
1999	94	26	68	0	60	80	99	PM2.5

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in South Carolina with a similar median AQI in 2025

All monitored counties in South Carolina

Source: U.S. EPA AirData, “Annual AQI by County” files for 1999–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem