EnviroNearby

Aiken County, South Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Aiken, South Carolina, 1985–2025.

91%
Good days in 2025
39
Median daily AQI, 2025
0
Days above 100 in 2025
266
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Aiken, South Carolina on 266 days. 241 of those days (91%) were in the Good range, and the median daily AQI was 39. 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 266 days. Across the years with fuller monitoring, the share of Good days rose: an average of 70% in 1986–1988 versus 90% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (266 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 (1985, 2018, 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%1985: Good 53 of 53 days19851986: Good 198 of 282 days1986: Moderate 54 of 282 days1986: Unhealthy for Sensitive Groups 20 of 282 days1986: Unhealthy 9 of 282 days1986: Very Unhealthy 1 of 282 days1987: Good 202 of 318 days1987: Moderate 72 of 318 days1987: Unhealthy for Sensitive Groups 37 of 318 days1987: Unhealthy 7 of 318 days1988: Good 265 of 352 days1988: Moderate 64 of 352 days1988: Unhealthy for Sensitive Groups 20 of 352 days1988: Unhealthy 3 of 352 days1989: Good 238 of 276 days1989: Moderate 34 of 276 days1989: Unhealthy for Sensitive Groups 4 of 276 days1990: Good 207 of 314 days1990: Moderate 76 of 314 days1990: Unhealthy for Sensitive Groups 21 of 314 days1990: Unhealthy 10 of 314 days19901991: Good 226 of 253 days1991: Moderate 25 of 253 days1991: Unhealthy for Sensitive Groups 2 of 253 days1992: Good 283 of 323 days1992: Moderate 33 of 323 days1992: Unhealthy for Sensitive Groups 7 of 323 days1993: Good 229 of 307 days1993: Moderate 64 of 307 days1993: Unhealthy for Sensitive Groups 13 of 307 days1993: Unhealthy 1 of 307 days1994: Good 295 of 359 days1994: Moderate 54 of 359 days1994: Unhealthy for Sensitive Groups 9 of 359 days1994: Unhealthy 1 of 359 days1995: Good 306 of 355 days1995: Moderate 44 of 355 days1995: Unhealthy for Sensitive Groups 5 of 355 days19951996: Good 266 of 340 days1996: Moderate 56 of 340 days1996: Unhealthy for Sensitive Groups 15 of 340 days1996: Unhealthy 3 of 340 days1997: Good 273 of 365 days1997: Moderate 64 of 365 days1997: Unhealthy for Sensitive Groups 25 of 365 days1997: Unhealthy 3 of 365 days1998: Good 236 of 364 days1998: Moderate 67 of 364 days1998: Unhealthy for Sensitive Groups 40 of 364 days1998: Unhealthy 21 of 364 days1999: Good 244 of 334 days1999: Moderate 50 of 334 days1999: Unhealthy for Sensitive Groups 37 of 334 days1999: Unhealthy 3 of 334 days2000: Good 202 of 322 days2000: Moderate 75 of 322 days2000: Unhealthy for Sensitive Groups 36 of 322 days2000: Unhealthy 9 of 322 days20002001: Good 255 of 364 days2001: Moderate 71 of 364 days2001: Unhealthy for Sensitive Groups 35 of 364 days2001: Unhealthy 3 of 364 days2002: Good 253 of 353 days2002: Moderate 71 of 353 days2002: Unhealthy for Sensitive Groups 22 of 353 days2002: Unhealthy 7 of 353 days2003: Good 291 of 339 days2003: Moderate 45 of 339 days2003: Unhealthy for Sensitive Groups 3 of 339 days2004: Good 261 of 364 days2004: Moderate 85 of 364 days2004: Unhealthy for Sensitive Groups 18 of 364 days2005: Good 229 of 363 days2005: Moderate 118 of 363 days2005: Unhealthy for Sensitive Groups 16 of 363 days20052006: Good 232 of 365 days2006: Moderate 122 of 365 days2006: Unhealthy for Sensitive Groups 11 of 365 days2007: Good 246 of 362 days2007: Moderate 98 of 362 days2007: Unhealthy for Sensitive Groups 18 of 362 days2008: Good 177 of 265 days2008: Moderate 77 of 265 days2008: Unhealthy for Sensitive Groups 11 of 265 days2009: Good 245 of 287 days2009: Moderate 40 of 287 days2009: Unhealthy for Sensitive Groups 2 of 287 days2010: Good 241 of 296 days2010: Moderate 55 of 296 days20102011: Good 195 of 259 days2011: Moderate 63 of 259 days2011: Unhealthy for Sensitive Groups 1 of 259 days2012: Good 215 of 226 days2012: Moderate 11 of 226 days2013: Good 209 of 219 days2013: Moderate 10 of 219 days2014: Good 188 of 213 days2014: Moderate 25 of 213 days2015: Good 236 of 247 days2015: Moderate 11 of 247 days20152016: Good 217 of 242 days2016: Moderate 25 of 242 days2017: Good 259 of 269 days2017: Moderate 10 of 269 days2018: Good 92 of 110 days2018: Moderate 18 of 110 days2019: Good 103 of 113 days2019: Moderate 10 of 113 days2020: Good 258 of 259 days2020: Moderate 1 of 259 days20202021: Good 259 of 282 days2021: Moderate 23 of 282 days2022: Good 246 of 271 days2022: Moderate 25 of 271 days2023: Good 252 of 275 days2023: Moderate 23 of 275 days2024: Good 238 of 267 days2024: Moderate 29 of 267 days2025: Good 241 of 266 days2025: Moderate 25 of 266 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 year0501001501985: 90th percentile AQI 371986: 90th percentile AQI 1011987: 90th percentile AQI 1081988: 90th percentile AQI 871989: 90th percentile AQI 611990: 90th percentile AQI 1001991: 90th percentile AQI 511992: 90th percentile AQI 541993: 90th percentile AQI 871994: 90th percentile AQI 711995: 90th percentile AQI 611996: 90th percentile AQI 801997: 90th percentile AQI 901998: 90th percentile AQI 1261999: 90th percentile AQI 1082000: 90th percentile AQI 1122001: 90th percentile AQI 1012002: 90th percentile AQI 972003: 90th percentile AQI 612004: 90th percentile AQI 812005: 90th percentile AQI 872006: 90th percentile AQI 812007: 90th percentile AQI 842008: 90th percentile AQI 842009: 90th percentile AQI 542010: 90th percentile AQI 582011: 90th percentile AQI 712012: 90th percentile AQI 472013: 90th percentile AQI 492014: 90th percentile AQI 542015: 90th percentile AQI 492016: 90th percentile AQI 512017: 90th percentile AQI 482018: 90th percentile AQI 612019: 90th percentile AQI 502020: 90th percentile AQI 442021: 90th percentile AQI 492022: 90th percentile AQI 502023: 90th percentile AQI 492024: 90th percentile AQI 512025: 90th percentile AQI 501985: Median AQI 291986: Median AQI 371987: Median AQI 441988: Median AQI 401989: Median AQI 331990: Median AQI 441991: Median AQI 341992: Median AQI 331993: Median AQI 381994: Median AQI 351995: Median AQI 291996: Median AQI 341997: Median AQI 341998: Median AQI 401999: Median AQI 352000: Median AQI 412001: Median AQI 422002: Median AQI 392003: Median AQI 282004: Median AQI 352005: Median AQI 422006: Median AQI 432007: Median AQI 422008: Median AQI 442009: Median AQI 382010: Median AQI 392011: Median AQI 422012: Median AQI 362013: Median AQI 372014: Median AQI 402015: Median AQI 382016: Median AQI 402017: Median AQI 382018: Median AQI 422019: Median AQI 372020: Median AQI 322021: Median AQI 362022: Median AQI 372023: Median AQI 392024: Median AQI 392025: Median AQI 39198519901995200020052010201520202025
  • 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
Ozone266100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025266241250000395071Ozone
2024267238290000395184Ozone
2023275252230000394980Ozone
2022271246250000375087Ozone
2021282259230000364984Ozone
202025925810000324471Ozone
2019113103100000375097Ozone
201811092180000426193Ozone
2017269259100000384871Ozone
2016242217250000405184Ozone
2015247236110000384964Ozone
2014213188250000405487Ozone
2013219209100000374980Ozone
2012226215110000364793Ozone
20112591956310004271108Ozone
2010296241550000395897Ozone
20092872454020003854105Ozone
200826517777110004484150Ozone
200736224698180004284147Ozone
2006365232122110004381115Ozone
2005363229118160004287140Ozone
200436426185180003581147Ozone
20033392914530002861122Ozone
200235325371227003997185Ozone
2001364255713530042101197Ozone
2000322202753690041112197Ozone
1999334244503730035108190Ozone
19983642366740210040126190Ozone
199736527364253003490169Ozone
199634026656153003480190Ozone
19953553064450002961140Ozone
19943592955491003571169Ozone
199330722964131003887156Ozone
19923232833370003354136Ozone
19912532262520003451101Ozone
19903142077621100044100192Ozone
19892762383440003361122Ozone
198835226564203004087166Ozone
1987318202723770044108177Ozone
1986282198542091037101201Ozone
1985535300000293741Ozone

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 1985–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem