EnviroNearby

Charleston County, South Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Charleston, South Carolina, 1981–2025.

61%
Good days in 2025
47
Median daily AQI, 2025
1
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Charleston, South Carolina on 365 days. 222 of those days (61%) were in the Good range, and the median daily AQI was 47. That median is higher than 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 227 days. Across the years with fuller monitoring, the share of Good days fell: an average of 94% in 1981–1983 versus 64% in 2023–2025.

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%1981: Good 192 of 199 days1981: Moderate 7 of 199 days19811982: Good 315 of 334 days1982: Moderate 19 of 334 days1983: Good 291 of 318 days1983: Moderate 26 of 318 days1983: Unhealthy for Sensitive Groups 1 of 318 days1984: Good 276 of 302 days1984: Moderate 26 of 302 days1985: Good 334 of 347 days1985: Moderate 13 of 347 days1986: Good 293 of 309 days1986: Moderate 16 of 309 days19861987: Good 290 of 363 days1987: Moderate 59 of 363 days1987: Unhealthy for Sensitive Groups 12 of 363 days1987: Unhealthy 2 of 363 days1988: Good 259 of 366 days1988: Moderate 75 of 366 days1988: Unhealthy for Sensitive Groups 25 of 366 days1988: Unhealthy 7 of 366 days1989: Good 303 of 328 days1989: Moderate 24 of 328 days1989: Unhealthy 1 of 328 days1990: Good 331 of 348 days1990: Moderate 17 of 348 days1991: Good 349 of 365 days1991: Moderate 12 of 365 days1991: Unhealthy for Sensitive Groups 4 of 365 days19911992: Good 309 of 366 days1992: Moderate 50 of 366 days1992: Unhealthy for Sensitive Groups 6 of 366 days1992: Very Unhealthy 1 of 366 days1993: Good 310 of 365 days1993: Moderate 53 of 365 days1993: Unhealthy for Sensitive Groups 2 of 365 days1994: Good 314 of 365 days1994: Moderate 51 of 365 days1995: Good 279 of 365 days1995: Moderate 81 of 365 days1995: Unhealthy for Sensitive Groups 4 of 365 days1995: Unhealthy 1 of 365 days1996: Good 295 of 366 days1996: Moderate 67 of 366 days1996: Unhealthy for Sensitive Groups 3 of 366 days1996: Unhealthy 1 of 366 days19961997: Good 258 of 365 days1997: Moderate 101 of 365 days1997: Unhealthy for Sensitive Groups 3 of 365 days1997: Unhealthy 3 of 365 days1998: Good 273 of 365 days1998: Moderate 83 of 365 days1998: Unhealthy for Sensitive Groups 9 of 365 days1999: Good 109 of 365 days1999: Moderate 241 of 365 days1999: Unhealthy for Sensitive Groups 14 of 365 days1999: Unhealthy 1 of 365 days2000: Good 82 of 366 days2000: Moderate 271 of 366 days2000: Unhealthy for Sensitive Groups 11 of 366 days2000: Unhealthy 2 of 366 days2001: Good 103 of 365 days2001: Moderate 259 of 365 days2001: Unhealthy for Sensitive Groups 3 of 365 days20012002: Good 114 of 365 days2002: Moderate 242 of 365 days2002: Unhealthy for Sensitive Groups 8 of 365 days2002: Unhealthy 1 of 365 days2003: Good 128 of 365 days2003: Moderate 232 of 365 days2003: Unhealthy for Sensitive Groups 5 of 365 days2004: Good 108 of 366 days2004: Moderate 251 of 366 days2004: Unhealthy for Sensitive Groups 6 of 366 days2004: Unhealthy 1 of 366 days2005: Good 94 of 365 days2005: Moderate 255 of 365 days2005: Unhealthy for Sensitive Groups 16 of 365 days2006: Good 104 of 365 days2006: Moderate 244 of 365 days2006: Unhealthy for Sensitive Groups 16 of 365 days2006: Unhealthy 1 of 365 days20062007: Good 129 of 365 days2007: Moderate 231 of 365 days2007: Unhealthy for Sensitive Groups 4 of 365 days2007: Unhealthy 1 of 365 days2008: Good 118 of 366 days2008: Moderate 242 of 366 days2008: Unhealthy for Sensitive Groups 6 of 366 days2009: Good 141 of 365 days2009: Moderate 224 of 365 days2010: Good 157 of 365 days2010: Moderate 206 of 365 days2010: Unhealthy for Sensitive Groups 2 of 365 days2011: Good 146 of 365 days2011: Moderate 215 of 365 days2011: Unhealthy for Sensitive Groups 3 of 365 days2011: Unhealthy 1 of 365 days20112012: Good 148 of 366 days2012: Moderate 217 of 366 days2012: Unhealthy for Sensitive Groups 1 of 366 days2013: Good 228 of 365 days2013: Moderate 137 of 365 days2014: Good 193 of 365 days2014: Moderate 172 of 365 days2015: Good 256 of 365 days2015: Moderate 108 of 365 days2015: Unhealthy for Sensitive Groups 1 of 365 days2016: Good 239 of 360 days2016: Moderate 116 of 360 days2016: Unhealthy for Sensitive Groups 3 of 360 days2016: Unhealthy 2 of 360 days20162017: Good 231 of 361 days2017: Moderate 129 of 361 days2017: Unhealthy for Sensitive Groups 1 of 361 days2018: Good 269 of 359 days2018: Moderate 90 of 359 days2019: Good 262 of 357 days2019: Moderate 95 of 357 days2020: Good 264 of 366 days2020: Moderate 101 of 366 days2020: Unhealthy for Sensitive Groups 1 of 366 days2021: Good 197 of 365 days2021: Moderate 168 of 365 days20212022: Good 209 of 365 days2022: Moderate 156 of 365 days2023: Good 212 of 365 days2023: Moderate 153 of 365 days2024: Good 269 of 366 days2024: Moderate 97 of 366 days2025: Good 222 of 365 days2025: Moderate 142 of 365 days2025: Unhealthy for Sensitive Groups 1 of 365 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 year0501001981: 90th percentile AQI 221982: 90th percentile AQI 441983: 90th percentile AQI 491984: 90th percentile AQI 491985: 90th percentile AQI 391986: 90th percentile AQI 431987: 90th percentile AQI 741988: 90th percentile AQI 971989: 90th percentile AQI 491990: 90th percentile AQI 421991: 90th percentile AQI 441992: 90th percentile AQI 611993: 90th percentile AQI 581994: 90th percentile AQI 541995: 90th percentile AQI 611996: 90th percentile AQI 581997: 90th percentile AQI 741998: 90th percentile AQI 711999: 90th percentile AQI 832000: 90th percentile AQI 872001: 90th percentile AQI 762002: 90th percentile AQI 772003: 90th percentile AQI 742004: 90th percentile AQI 772005: 90th percentile AQI 802006: 90th percentile AQI 862007: 90th percentile AQI 772008: 90th percentile AQI 712009: 90th percentile AQI 632010: 90th percentile AQI 672011: 90th percentile AQI 712012: 90th percentile AQI 662013: 90th percentile AQI 602014: 90th percentile AQI 612015: 90th percentile AQI 582016: 90th percentile AQI 582017: 90th percentile AQI 602018: 90th percentile AQI 552019: 90th percentile AQI 562020: 90th percentile AQI 572021: 90th percentile AQI 622022: 90th percentile AQI 592023: 90th percentile AQI 642024: 90th percentile AQI 582025: 90th percentile AQI 591981: Median AQI 91982: Median AQI 201983: Median AQI 111984: Median AQI 161985: Median AQI 191986: Median AQI 161987: Median AQI 361988: Median AQI 421989: Median AQI 261990: Median AQI 201991: Median AQI 311992: Median AQI 361993: Median AQI 381994: Median AQI 341995: Median AQI 371996: Median AQI 371997: Median AQI 421998: Median AQI 391999: Median AQI 572000: Median AQI 592001: Median AQI 572002: Median AQI 552003: Median AQI 552004: Median AQI 562005: Median AQI 572006: Median AQI 572007: Median AQI 552008: Median AQI 552009: Median AQI 532010: Median AQI 522011: Median AQI 532012: Median AQI 522013: Median AQI 442014: Median AQI 482015: Median AQI 432016: Median AQI 442017: Median AQI 442018: Median AQI 412019: Median AQI 422020: Median AQI 432021: Median AQI 482022: Median AQI 472023: Median AQI 472024: Median AQI 432025: Median AQI 471981198619911996200120062011201620212025
  • 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
Fine particles (PM2.5)22762%
Ozone13637%
Coarse particles (PM10)21%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536522214210004759105PM2.5
2024366269970000435877PM2.5
20233652121530000476493PM2.5
20223652091560000475984PM2.5
20213651971680000486293PM2.5
202036626410110004357117PM2.5
2019357262950000425676PM2.5
2018359269900000415579PM2.5
201736123112910004460101PM2.5
201636023911632004458160PM2.5
201536525610810004358114PM2.5
20143651931720000486180PM2.5
20133652281370000446084PM2.5
201236614821710005266134PM2.5
201136514621531005371153PM2.5
201036515720620005267112PM2.5
20093651412240000536386PM2.5
200836611824260005571115PM2.5
200736512923141005577162PM2.5
2006365104244161005786159PM2.5
200536594255160005780140PM2.5
200436610825161005677151PM2.5
200336512823250005574136PM2.5
200236511424281005577159PM2.5
200136510325930005776108PM2.5
200036682271112005987174PM2.5
1999365109241141005783151PM2.5
19983652738390003971133Ozone
199736525810133004274166Ozone
19963662956731003758177Ozone
19953652798141003761161Ozone
1994365314510000345497Ozone
19933653105320003858126Ozone
19923663095060103661203Ozone
19913653491240003144128Ozone
1990348331170000204276CO
19893283032401002649156Ozone
198836625975257004297185Ozone
198736329059122003674164Ozone
1986309293160000164385CO
1985347334130000193970CO
1984302276260000164993CO
19833182912610001149102CO
1982334315190000204493CO
19811991927000092284CO

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 1981–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem