EnviroNearby

Colleton County, South Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Colleton, South Carolina, 1980–2019.

82%
Good days in 2018
36
Median daily AQI, 2018
0
Days above 100 in 2018
359
Days with an AQI in 2018 (of 365)

In 2018, EPA reported a daily Air Quality Index (AQI) for Colleton, South Carolina on 359 days. 294 of those days (82%) were in the Good range, and the median daily AQI was 36. That median is lower than the typical monitored county in South Carolina (median 39 across 17 counties), and lower than the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 274 days. Across the years with fuller monitoring, the share of Good days rose: an average of 73% in 1980–1982 versus 78% in 2016–2018.

The most recent year with data for this county is 2019; EPA's files for 2020–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (1985, 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%1980: Good 127 of 154 days1980: Moderate 26 of 154 days1980: Unhealthy for Sensitive Groups 1 of 154 days19801981: Good 131 of 198 days1981: Moderate 52 of 198 days1981: Unhealthy for Sensitive Groups 13 of 198 days1981: Unhealthy 2 of 198 days1982: Good 142 of 204 days1982: Moderate 45 of 204 days1982: Unhealthy for Sensitive Groups 15 of 204 days1982: Unhealthy 2 of 204 days1983: Good 164 of 235 days1983: Moderate 53 of 235 days1983: Unhealthy for Sensitive Groups 14 of 235 days1983: Unhealthy 4 of 235 days1984: Good 217 of 308 days1984: Moderate 70 of 308 days1984: Unhealthy for Sensitive Groups 21 of 308 days1985: Good 34 of 48 days1985: Moderate 11 of 48 days1985: Unhealthy for Sensitive Groups 3 of 48 days19851986: Good 96 of 137 days1986: Moderate 35 of 137 days1986: Unhealthy for Sensitive Groups 4 of 137 days1986: Unhealthy 2 of 137 days1987: Good 110 of 152 days1987: Moderate 33 of 152 days1987: Unhealthy for Sensitive Groups 8 of 152 days1987: Unhealthy 1 of 152 days1989: Good 95 of 126 days1989: Moderate 24 of 126 days1989: Unhealthy for Sensitive Groups 7 of 126 days1990: Good 162 of 264 days1990: Moderate 82 of 264 days1990: Unhealthy for Sensitive Groups 18 of 264 days1990: Unhealthy 2 of 264 days1991: Good 307 of 354 days1991: Moderate 45 of 354 days1991: Unhealthy for Sensitive Groups 2 of 354 days19911992: Good 194 of 239 days1992: Moderate 33 of 239 days1992: Unhealthy for Sensitive Groups 11 of 239 days1992: Unhealthy 1 of 239 days1993: Good 135 of 201 days1993: Moderate 51 of 201 days1993: Unhealthy for Sensitive Groups 15 of 201 days1994: Good 293 of 343 days1994: Moderate 43 of 343 days1994: Unhealthy for Sensitive Groups 5 of 343 days1994: Unhealthy 2 of 343 days1995: Good 248 of 314 days1995: Moderate 62 of 314 days1995: Unhealthy for Sensitive Groups 4 of 314 days1996: Good 291 of 357 days1996: Moderate 53 of 357 days1996: Unhealthy for Sensitive Groups 13 of 357 days19961997: Good 173 of 248 days1997: Moderate 58 of 248 days1997: Unhealthy for Sensitive Groups 17 of 248 days1998: Good 123 of 236 days1998: Moderate 91 of 236 days1998: Unhealthy for Sensitive Groups 17 of 236 days1998: Unhealthy 5 of 236 days1999: Good 105 of 222 days1999: Moderate 86 of 222 days1999: Unhealthy for Sensitive Groups 30 of 222 days1999: Unhealthy 1 of 222 days2000: Good 127 of 231 days2000: Moderate 81 of 231 days2000: Unhealthy for Sensitive Groups 22 of 231 days2000: Unhealthy 1 of 231 days2001: Good 165 of 248 days2001: Moderate 69 of 248 days2001: Unhealthy for Sensitive Groups 14 of 248 days20012002: Good 148 of 222 days2002: Moderate 62 of 222 days2002: Unhealthy for Sensitive Groups 9 of 222 days2002: Unhealthy 3 of 222 days2003: Good 189 of 230 days2003: Moderate 38 of 230 days2003: Unhealthy for Sensitive Groups 3 of 230 days2004: Good 187 of 231 days2004: Moderate 40 of 231 days2004: Unhealthy for Sensitive Groups 4 of 231 days2005: Good 226 of 284 days2005: Moderate 50 of 284 days2005: Unhealthy for Sensitive Groups 8 of 284 days2006: Good 265 of 349 days2006: Moderate 76 of 349 days2006: Unhealthy for Sensitive Groups 8 of 349 days20062007: Good 282 of 363 days2007: Moderate 76 of 363 days2007: Unhealthy for Sensitive Groups 5 of 363 days2008: Good 301 of 362 days2008: Moderate 58 of 362 days2008: Unhealthy for Sensitive Groups 3 of 362 days2009: Good 327 of 347 days2009: Moderate 20 of 347 days2010: Good 311 of 345 days2010: Moderate 32 of 345 days2010: Unhealthy for Sensitive Groups 2 of 345 days2011: Good 175 of 349 days2011: Moderate 171 of 349 days2011: Unhealthy for Sensitive Groups 2 of 349 days2011: Unhealthy 1 of 349 days20112012: Good 192 of 325 days2012: Moderate 133 of 325 days2013: Good 240 of 334 days2013: Moderate 94 of 334 days2014: Good 233 of 336 days2014: Moderate 102 of 336 days2014: Unhealthy 1 of 336 days2015: Good 252 of 299 days2015: Moderate 47 of 299 days2016: Good 264 of 343 days2016: Moderate 76 of 343 days2016: Unhealthy for Sensitive Groups 2 of 343 days2016: Unhealthy 1 of 343 days20162017: Good 263 of 357 days2017: Moderate 94 of 357 days2018: Good 294 of 359 days2018: Moderate 65 of 359 days2019: Good 7 of 7 days2019
  • 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 year0501001501980: 90th percentile AQI 641981: 90th percentile AQI 971982: 90th percentile AQI 931983: 90th percentile AQI 931984: 90th percentile AQI 871985: 90th percentile AQI 841986: 90th percentile AQI 871987: 90th percentile AQI 871989: 90th percentile AQI 671990: 90th percentile AQI 931991: 90th percentile AQI 611992: 90th percentile AQI 801993: 90th percentile AQI 901994: 90th percentile AQI 611995: 90th percentile AQI 641996: 90th percentile AQI 671997: 90th percentile AQI 841998: 90th percentile AQI 971999: 90th percentile AQI 1122000: 90th percentile AQI 1002001: 90th percentile AQI 842002: 90th percentile AQI 902003: 90th percentile AQI 642004: 90th percentile AQI 612005: 90th percentile AQI 742006: 90th percentile AQI 772007: 90th percentile AQI 712008: 90th percentile AQI 642009: 90th percentile AQI 482010: 90th percentile AQI 502011: 90th percentile AQI 682012: 90th percentile AQI 592013: 90th percentile AQI 582014: 90th percentile AQI 572015: 90th percentile AQI 522016: 90th percentile AQI 582017: 90th percentile AQI 572018: 90th percentile AQI 542019: 90th percentile AQI 411980: Median AQI 371981: Median AQI 441982: Median AQI 411983: Median AQI 401984: Median AQI 411985: Median AQI 371986: Median AQI 441987: Median AQI 401989: Median AQI 391990: Median AQI 471991: Median AQI 361992: Median AQI 361993: Median AQI 441994: Median AQI 321995: Median AQI 371996: Median AQI 361997: Median AQI 411998: Median AQI 501999: Median AQI 542000: Median AQI 492001: Median AQI 442002: Median AQI 432003: Median AQI 362004: Median AQI 382005: Median AQI 372006: Median AQI 402007: Median AQI 412008: Median AQI 372009: Median AQI 352010: Median AQI 362011: Median AQI 502012: Median AQI 462013: Median AQI 392014: Median AQI 422015: Median AQI 372016: Median AQI 392017: Median AQI 412018: Median AQI 362019: Median AQI 26198019851991199620012006201120162019
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2018

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)27476%
Ozone8524%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20197700000264141PM2.5
2018359294650000365479PM2.5
2017357263940000415784PM2.5
20163432647621003958153PM2.5
2015299252470000375272Ozone
201433623310201004257152PM2.5
20133342409400003958100PM2.5
20123251921330000465976PM2.5
201134917517121005068164PM2.5
20103453113220003650108Ozone
2009347327200000354880Ozone
20083623015830003764115Ozone
20073632827650004171119Ozone
20063492657680004077136Ozone
20052842265080003774126Ozone
20042311874040003861112Ozone
20032301893830003664119Ozone
20022221486293004390159Ozone
200124816569140004484147Ozone
2000231127812210049100179Ozone
1999222105863010054112151Ozone
199823612391175005097159Ozone
199724817358170004184143Ozone
199635729153130003667147Ozone
19953142486240003764143Ozone
19943432934352003261161Ozone
199320113551150004490147Ozone
199223919433111003680161Ozone
19913543074520003661115Ozone
199026416282182004793156Ozone
1989126952470003967133Ozone
19871521103381004087154Ozone
1986137963542004487169Ozone
198548341130003784150Ozone
198430821770210004187150Ozone
198323516453144004093174Ozone
198220414245152004193159Ozone
198119813152132004497161Ozone
19801541272610003764101Ozone

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 2018

All monitored counties in South Carolina

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2019 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem