EnviroNearby

Chesterfield County, South Carolina air quality history

Daily Air Quality Index summaries from EPA monitors in Chesterfield, South Carolina, 2000–2025.

64%
Good days in 2025
44
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 Chesterfield, South Carolina on 365 days. 234 of those days (64%) 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 254 days. Across the years with fuller monitoring, the share of Good days rose: an average of 61% in 2002–2004 versus 65% in 2023–2025.

Years with fewer than 120 monitored days (2000, 2001) 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%2000: Good 24 of 103 days2000: Moderate 79 of 103 days20002001: Good 36 of 113 days2001: Moderate 77 of 113 days2002: Good 158 of 308 days2002: Moderate 112 of 308 days2002: Unhealthy for Sensitive Groups 28 of 308 days2002: Unhealthy 10 of 308 days20022003: Good 236 of 359 days2003: Moderate 111 of 359 days2003: Unhealthy for Sensitive Groups 11 of 359 days2003: Unhealthy 1 of 359 days2004: Good 235 of 359 days2004: Moderate 114 of 359 days2004: Unhealthy for Sensitive Groups 9 of 359 days2004: Unhealthy 1 of 359 days20042005: Good 227 of 353 days2005: Moderate 113 of 353 days2005: Unhealthy for Sensitive Groups 13 of 353 days2006: Good 206 of 359 days2006: Moderate 146 of 359 days2006: Unhealthy for Sensitive Groups 6 of 359 days2006: Unhealthy 1 of 359 days20062007: Good 211 of 360 days2007: Moderate 139 of 360 days2007: Unhealthy for Sensitive Groups 10 of 360 days2008: Good 243 of 363 days2008: Moderate 114 of 363 days2008: Unhealthy for Sensitive Groups 6 of 363 days20082009: Good 272 of 361 days2009: Moderate 89 of 361 days2010: Good 225 of 345 days2010: Moderate 117 of 345 days2010: Unhealthy for Sensitive Groups 3 of 345 days20102011: Good 197 of 299 days2011: Moderate 100 of 299 days2011: Unhealthy for Sensitive Groups 2 of 299 days2012: Good 185 of 261 days2012: Moderate 74 of 261 days2012: Unhealthy for Sensitive Groups 1 of 261 days2012: Unhealthy 1 of 261 days20122013: Good 183 of 350 days2013: Moderate 167 of 350 days2014: Good 147 of 351 days2014: Moderate 204 of 351 days20142015: Good 218 of 357 days2015: Moderate 139 of 357 days2016: Good 250 of 356 days2016: Moderate 105 of 356 days2016: Unhealthy for Sensitive Groups 1 of 356 days20162017: Good 288 of 358 days2017: Moderate 69 of 358 days2017: Unhealthy for Sensitive Groups 1 of 358 days2018: Good 266 of 338 days2018: Moderate 71 of 338 days2018: Unhealthy for Sensitive Groups 1 of 338 days20182019: Good 284 of 364 days2019: Moderate 80 of 364 days2020: Good 287 of 346 days2020: Moderate 59 of 346 days20202021: Good 268 of 358 days2021: Moderate 90 of 358 days2022: Good 273 of 343 days2022: Moderate 70 of 343 days20222023: Good 242 of 365 days2023: Moderate 122 of 365 days2023: Unhealthy for Sensitive Groups 1 of 365 days2024: Good 234 of 364 days2024: Moderate 128 of 364 days2024: Unhealthy for Sensitive Groups 2 of 364 days20242025: Good 234 of 365 days2025: Moderate 130 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 year0501001502000: 90th percentile AQI 762001: 90th percentile AQI 742002: 90th percentile AQI 1122003: 90th percentile AQI 772004: 90th percentile AQI 772005: 90th percentile AQI 802006: 90th percentile AQI 842007: 90th percentile AQI 842008: 90th percentile AQI 712009: 90th percentile AQI 612010: 90th percentile AQI 672011: 90th percentile AQI 672012: 90th percentile AQI 582013: 90th percentile AQI 632014: 90th percentile AQI 632015: 90th percentile AQI 602016: 90th percentile AQI 592017: 90th percentile AQI 552018: 90th percentile AQI 562019: 90th percentile AQI 562020: 90th percentile AQI 532021: 90th percentile AQI 582022: 90th percentile AQI 552023: 90th percentile AQI 622024: 90th percentile AQI 602025: 90th percentile AQI 582000: Median AQI 562001: Median AQI 562002: Median AQI 492003: Median AQI 432004: Median AQI 412005: Median AQI 442006: Median AQI 462007: Median AQI 472008: Median AQI 432009: Median AQI 412010: Median AQI 442011: Median AQI 452012: Median AQI 432013: Median AQI 492014: Median AQI 522015: Median AQI 472016: Median AQI 422017: Median AQI 402018: Median AQI 362019: Median AQI 342020: Median AQI 392021: Median AQI 412022: Median AQI 402023: Median AQI 422024: Median AQI 442025: Median AQI 4420002002200420062008201020122014201620182020202220242025
  • 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)25470%
Ozone11130%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536523413010004458103PM2.5
202436423412820004460143PM2.5
202336524212210004262134PM2.5
2022343273700000405597PM2.5
2021358268900000415881PM2.5
2020346287590000395391PM2.5
2019364284800000345677PM2.5
20183382667110003656104PM2.5
20173582886910004055112Ozone
201635625010510004259139PM2.5
20153572181390000476091PM2.5
20143511472040000526380PM2.5
20133501831670000496380PM2.5
20122611857411004358151Ozone
201129919710020004567108Ozone
201034522511730004467126Ozone
2009361272890000416193Ozone
200836324311460004371126Ozone
2007360211139100004784136Ozone
200635920614661004684160Ozone
2005353227113130004480143Ozone
200435923511491004177154Ozone
2003359236111111004377151Ozone
200230815811228100049112172Ozone
200111336770000567486PM2.5
200010324790000567691PM2.5

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 2000–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem