EnviroNearby

Anderson County, South Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Anderson, South Carolina, 1991–2025.

91%
Good days in 2025
40
Median daily AQI, 2025
0
Days above 100 in 2025
264
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Anderson, South Carolina on 264 days. 241 of those days (91%) were in the Good range, and the median daily AQI was 40. That median is lower than the typical monitored county in South Carolina (median 43 across 13 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 264 days. Across the years with fuller monitoring, the share of Good days rose: an average of 75% in 1991–1993 versus 87% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (264 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

Years with fewer than 120 monitored days (2019) 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.

Share of monitored days in each AQI category, by year0%25%50%75%100%1991: Good 142 of 181 days1991: Moderate 31 of 181 days1991: Unhealthy for Sensitive Groups 8 of 181 days19911992: Good 276 of 342 days1992: Moderate 58 of 342 days1992: Unhealthy for Sensitive Groups 7 of 342 days1992: Unhealthy 1 of 342 days1993: Good 235 of 357 days1993: Moderate 80 of 357 days1993: Unhealthy for Sensitive Groups 35 of 357 days1993: Unhealthy 5 of 357 days1993: Very Unhealthy 2 of 357 days1994: Good 263 of 349 days1994: Moderate 71 of 349 days1994: Unhealthy for Sensitive Groups 11 of 349 days1994: Unhealthy 4 of 349 days1995: Good 240 of 342 days1995: Moderate 69 of 342 days1995: Unhealthy for Sensitive Groups 28 of 342 days1995: Unhealthy 4 of 342 days1995: Very Unhealthy 1 of 342 days1996: Good 267 of 355 days1996: Moderate 69 of 355 days1996: Unhealthy for Sensitive Groups 15 of 355 days1996: Unhealthy 3 of 355 days1996: Very Unhealthy 1 of 355 days19961997: Good 245 of 361 days1997: Moderate 74 of 361 days1997: Unhealthy for Sensitive Groups 38 of 361 days1997: Unhealthy 4 of 361 days1998: Good 218 of 360 days1998: Moderate 71 of 360 days1998: Unhealthy for Sensitive Groups 51 of 360 days1998: Unhealthy 18 of 360 days1998: Very Unhealthy 2 of 360 days1999: Good 198 of 326 days1999: Moderate 68 of 326 days1999: Unhealthy for Sensitive Groups 46 of 326 days1999: Unhealthy 13 of 326 days1999: Very Unhealthy 1 of 326 days2000: Good 164 of 308 days2000: Moderate 89 of 308 days2000: Unhealthy for Sensitive Groups 52 of 308 days2000: Unhealthy 3 of 308 days2001: Good 124 of 231 days2001: Moderate 70 of 231 days2001: Unhealthy for Sensitive Groups 30 of 231 days2001: Unhealthy 7 of 231 days20012002: Good 129 of 234 days2002: Moderate 56 of 234 days2002: Unhealthy for Sensitive Groups 33 of 234 days2002: Unhealthy 16 of 234 days2003: Good 129 of 221 days2003: Moderate 74 of 221 days2003: Unhealthy for Sensitive Groups 18 of 221 days2004: Good 143 of 216 days2004: Moderate 60 of 216 days2004: Unhealthy for Sensitive Groups 13 of 216 days2005: Good 114 of 211 days2005: Moderate 78 of 211 days2005: Unhealthy for Sensitive Groups 19 of 211 days2006: Good 178 of 215 days2006: Moderate 36 of 215 days2006: Unhealthy for Sensitive Groups 1 of 215 days20062008: Good 152 of 192 days2008: Moderate 38 of 192 days2008: Unhealthy for Sensitive Groups 2 of 192 days2009: Good 339 of 363 days2009: Moderate 24 of 363 days2010: Good 253 of 337 days2010: Moderate 79 of 337 days2010: Unhealthy for Sensitive Groups 5 of 337 days2011: Good 175 of 263 days2011: Moderate 82 of 263 days2011: Unhealthy for Sensitive Groups 6 of 263 days2012: Good 154 of 186 days2012: Moderate 27 of 186 days2012: Unhealthy for Sensitive Groups 4 of 186 days2012: Unhealthy 1 of 186 days20122013: Good 211 of 221 days2013: Moderate 10 of 221 days2014: Good 199 of 218 days2014: Moderate 19 of 218 days2015: Good 185 of 200 days2015: Moderate 15 of 200 days2016: Good 240 of 256 days2016: Moderate 16 of 256 days2017: Good 254 of 264 days2017: Moderate 10 of 264 days20172018: Good 147 of 148 days2018: Moderate 1 of 148 days2019: Good 66 of 85 days2019: Moderate 18 of 85 days2019: Unhealthy for Sensitive Groups 1 of 85 days2020: Good 257 of 265 days2020: Moderate 8 of 265 days2021: Good 240 of 263 days2021: Moderate 23 of 263 days2022: Good 230 of 246 days2022: Moderate 16 of 246 days20222023: Good 233 of 270 days2023: Moderate 37 of 270 days2024: Good 213 of 255 days2024: Moderate 41 of 255 days2024: Unhealthy for Sensitive Groups 1 of 255 days2025: Good 241 of 264 days2025: Moderate 23 of 264 days2025
  • 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 and 90th-percentile daily AQI, by year0501001501991: 90th percentile AQI 741992: 90th percentile AQI 711993: 90th percentile AQI 1011994: 90th percentile AQI 801995: 90th percentile AQI 971996: 90th percentile AQI 801997: 90th percentile AQI 1051998: 90th percentile AQI 1291999: 90th percentile AQI 1222000: 90th percentile AQI 1192001: 90th percentile AQI 1152002: 90th percentile AQI 1432003: 90th percentile AQI 972004: 90th percentile AQI 932005: 90th percentile AQI 1002006: 90th percentile AQI 582008: 90th percentile AQI 712009: 90th percentile AQI 492010: 90th percentile AQI 742011: 90th percentile AQI 802012: 90th percentile AQI 612013: 90th percentile AQI 462014: 90th percentile AQI 502015: 90th percentile AQI 492016: 90th percentile AQI 492017: 90th percentile AQI 452018: 90th percentile AQI 462019: 90th percentile AQI 672020: 90th percentile AQI 462021: 90th percentile AQI 502022: 90th percentile AQI 482023: 90th percentile AQI 582024: 90th percentile AQI 612025: 90th percentile AQI 501991: Median AQI 371992: Median AQI 371993: Median AQI 401994: Median AQI 391995: Median AQI 381996: Median AQI 401997: Median AQI 421998: Median AQI 461999: Median AQI 442000: Median AQI 482001: Median AQI 492002: Median AQI 482003: Median AQI 472004: Median AQI 452005: Median AQI 492006: Median AQI 412008: Median AQI 382009: Median AQI 352010: Median AQI 412011: Median AQI 452012: Median AQI 412013: Median AQI 342014: Median AQI 382015: Median AQI 382016: Median AQI 412017: Median AQI 372018: Median AQI 352019: Median AQI 422020: Median AQI 352021: Median AQI 382022: Median AQI 392023: Median AQI 422024: Median AQI 432025: Median AQI 4019911996200120062012201720222025
  • 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.

PollutantDays as main pollutantShare of monitored days
Ozone264100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025264241230000405084Ozone
20242552134110004361115Ozone
2023270233370000425897Ozone
2022246230160000394874Ozone
2021263240230000385087Ozone
202026525780000354671Ozone
201985661810004267108Ozone
201814814710000354651Ozone
2017264254100000374580Ozone
2016256240160000414990Ozone
2015200185150000384980Ozone
2014218199190000385074Ozone
2013221211100000344680Ozone
20121861542741004161161Ozone
20112631758260004580150Ozone
20103372537950004174126Ozone
2009363339240000354987Ozone
20081921523820003871136Ozone
20062151783610004158143Ozone
2005211114781900049100147Ozone
200421614360130004593140Ozone
200322112974180004797150Ozone
20022341295633160048143195Ozone
2001231124703070049115182Ozone
2000308164895230048119192Ozone
19993261986846131044122208Ozone
19983602187151182046129216Ozone
1997361245743840042105166Ozone
199635526769153104080208Ozone
199534224069284103897203Ozone
199434926371114003980179Ozone
1993357235803552040101212Ozone
19923422765871003771154Ozone
19911811423180003774136Ozone

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 1991–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem