EnviroNearby

Charles County, Maryland air quality history

Daily Air Quality Index summaries from EPA monitors in Charles, Maryland, 1984–2025.

92%
Good days in 2025
38
Median daily AQI, 2025
0
Days above 100 in 2025
236
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Charles, Maryland on 236 days. 218 of those days (92%) were in the Good range, and the median daily AQI was 38. That median is about the same as the typical monitored county in Maryland (median 39.5 across 16 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 236 days. Across the years with fuller monitoring, the share of Good days rose: an average of 61% in 1985–1987 versus 88% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (236 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 (1984) 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%1984: Good 58 of 60 days1984: Moderate 2 of 60 days19841985: Good 142 of 251 days1985: Moderate 58 of 251 days1985: Unhealthy for Sensitive Groups 35 of 251 days1985: Unhealthy 15 of 251 days1985: Very Unhealthy 1 of 251 days1986: Good 225 of 354 days1986: Moderate 69 of 354 days1986: Unhealthy for Sensitive Groups 40 of 354 days1986: Unhealthy 19 of 354 days1986: Very Unhealthy 1 of 354 days1987: Good 215 of 335 days1987: Moderate 59 of 335 days1987: Unhealthy for Sensitive Groups 34 of 335 days1987: Unhealthy 21 of 335 days1987: Very Unhealthy 6 of 335 days1988: Good 169 of 286 days1988: Moderate 51 of 286 days1988: Unhealthy for Sensitive Groups 35 of 286 days1988: Unhealthy 17 of 286 days1988: Very Unhealthy 14 of 286 days1989: Good 256 of 333 days1989: Moderate 54 of 333 days1989: Unhealthy for Sensitive Groups 21 of 333 days1989: Unhealthy 2 of 333 days19891990: Good 227 of 326 days1990: Moderate 70 of 326 days1990: Unhealthy for Sensitive Groups 25 of 326 days1990: Unhealthy 3 of 326 days1990: Very Unhealthy 1 of 326 days1991: Good 103 of 209 days1991: Moderate 57 of 209 days1991: Unhealthy for Sensitive Groups 33 of 209 days1991: Unhealthy 16 of 209 days1992: Good 129 of 204 days1992: Moderate 57 of 204 days1992: Unhealthy for Sensitive Groups 14 of 204 days1992: Unhealthy 3 of 204 days1992: Very Unhealthy 1 of 204 days1993: Good 96 of 202 days1993: Moderate 58 of 202 days1993: Unhealthy for Sensitive Groups 33 of 202 days1993: Unhealthy 11 of 202 days1993: Very Unhealthy 4 of 202 days1994: Good 119 of 191 days1994: Moderate 48 of 191 days1994: Unhealthy for Sensitive Groups 21 of 191 days1994: Unhealthy 3 of 191 days19941995: Good 103 of 207 days1995: Moderate 63 of 207 days1995: Unhealthy for Sensitive Groups 31 of 207 days1995: Unhealthy 10 of 207 days1996: Good 108 of 207 days1996: Moderate 69 of 207 days1996: Unhealthy for Sensitive Groups 25 of 207 days1996: Unhealthy 5 of 207 days1997: Good 104 of 206 days1997: Moderate 58 of 206 days1997: Unhealthy for Sensitive Groups 30 of 206 days1997: Unhealthy 12 of 206 days1997: Very Unhealthy 2 of 206 days1998: Good 91 of 210 days1998: Moderate 55 of 210 days1998: Unhealthy for Sensitive Groups 35 of 210 days1998: Unhealthy 26 of 210 days1998: Very Unhealthy 3 of 210 days1999: Good 93 of 213 days1999: Moderate 64 of 213 days1999: Unhealthy for Sensitive Groups 30 of 213 days1999: Unhealthy 21 of 213 days1999: Very Unhealthy 5 of 213 days19992000: Good 134 of 213 days2000: Moderate 46 of 213 days2000: Unhealthy for Sensitive Groups 28 of 213 days2000: Unhealthy 4 of 213 days2000: Very Unhealthy 1 of 213 days2001: Good 137 of 212 days2001: Moderate 49 of 212 days2001: Unhealthy for Sensitive Groups 17 of 212 days2001: Unhealthy 9 of 212 days2002: Good 107 of 207 days2002: Moderate 59 of 207 days2002: Unhealthy for Sensitive Groups 27 of 207 days2002: Unhealthy 12 of 207 days2002: Very Unhealthy 2 of 207 days2003: Good 140 of 203 days2003: Moderate 49 of 203 days2003: Unhealthy for Sensitive Groups 9 of 203 days2003: Unhealthy 2 of 203 days2003: Very Unhealthy 3 of 203 days2004: Good 141 of 205 days2004: Moderate 49 of 205 days2004: Unhealthy for Sensitive Groups 14 of 205 days2004: Unhealthy 1 of 205 days20042005: Good 133 of 212 days2005: Moderate 56 of 212 days2005: Unhealthy for Sensitive Groups 18 of 212 days2005: Unhealthy 5 of 212 days2006: Good 134 of 213 days2006: Moderate 58 of 213 days2006: Unhealthy for Sensitive Groups 18 of 213 days2006: Unhealthy 3 of 213 days2007: Good 106 of 214 days2007: Moderate 86 of 214 days2007: Unhealthy for Sensitive Groups 20 of 214 days2007: Unhealthy 2 of 214 days2008: Good 127 of 206 days2008: Moderate 61 of 206 days2008: Unhealthy for Sensitive Groups 16 of 206 days2008: Unhealthy 2 of 206 days2009: Good 168 of 214 days2009: Moderate 44 of 214 days2009: Unhealthy for Sensitive Groups 2 of 214 days20092010: Good 128 of 213 days2010: Moderate 72 of 213 days2010: Unhealthy for Sensitive Groups 10 of 213 days2010: Unhealthy 3 of 213 days2011: Good 142 of 207 days2011: Moderate 54 of 207 days2011: Unhealthy for Sensitive Groups 8 of 207 days2011: Unhealthy 3 of 207 days2012: Good 142 of 196 days2012: Moderate 41 of 196 days2012: Unhealthy for Sensitive Groups 10 of 196 days2012: Unhealthy 3 of 196 days2013: Good 167 of 198 days2013: Moderate 31 of 198 days2014: Good 173 of 209 days2014: Moderate 33 of 209 days2014: Unhealthy for Sensitive Groups 3 of 209 days20142015: Good 153 of 212 days2015: Moderate 58 of 212 days2015: Unhealthy for Sensitive Groups 1 of 212 days2016: Good 166 of 213 days2016: Moderate 41 of 213 days2016: Unhealthy for Sensitive Groups 6 of 213 days2017: Good 189 of 241 days2017: Moderate 52 of 241 days2018: Good 202 of 235 days2018: Moderate 32 of 235 days2018: Unhealthy for Sensitive Groups 1 of 235 days2019: Good 202 of 221 days2019: Moderate 19 of 221 days20192020: Good 235 of 236 days2020: Moderate 1 of 236 days2021: Good 215 of 242 days2021: Moderate 26 of 242 days2021: Unhealthy for Sensitive Groups 1 of 242 days2022: Good 225 of 245 days2022: Moderate 20 of 245 days2023: Good 199 of 243 days2023: Moderate 42 of 243 days2023: Unhealthy for Sensitive Groups 2 of 243 days2024: Good 209 of 232 days2024: Moderate 21 of 232 days2024: Unhealthy for Sensitive Groups 2 of 232 days20242025: Good 218 of 236 days2025: Moderate 18 of 236 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 year0501001502001984: 90th percentile AQI 431985: 90th percentile AQI 1331986: 90th percentile AQI 1291987: 90th percentile AQI 1401988: 90th percentile AQI 1611989: 90th percentile AQI 901990: 90th percentile AQI 1001991: 90th percentile AQI 1401992: 90th percentile AQI 1001993: 90th percentile AQI 1361994: 90th percentile AQI 1011995: 90th percentile AQI 1291996: 90th percentile AQI 1121997: 90th percentile AQI 1401998: 90th percentile AQI 1611999: 90th percentile AQI 1592000: 90th percentile AQI 1152001: 90th percentile AQI 1122002: 90th percentile AQI 1402003: 90th percentile AQI 972004: 90th percentile AQI 932005: 90th percentile AQI 1052006: 90th percentile AQI 1002007: 90th percentile AQI 1012008: 90th percentile AQI 932009: 90th percentile AQI 612010: 90th percentile AQI 872011: 90th percentile AQI 902012: 90th percentile AQI 872013: 90th percentile AQI 612014: 90th percentile AQI 642015: 90th percentile AQI 712016: 90th percentile AQI 712017: 90th percentile AQI 642018: 90th percentile AQI 542019: 90th percentile AQI 502020: 90th percentile AQI 442021: 90th percentile AQI 512022: 90th percentile AQI 502023: 90th percentile AQI 642024: 90th percentile AQI 502025: 90th percentile AQI 491984: Median AQI 241985: Median AQI 451986: Median AQI 411987: Median AQI 421988: Median AQI 461989: Median AQI 341990: Median AQI 391991: Median AQI 511992: Median AQI 441993: Median AQI 581994: Median AQI 471995: Median AQI 511996: Median AQI 491997: Median AQI 501998: Median AQI 611999: Median AQI 612000: Median AQI 452001: Median AQI 462002: Median AQI 502003: Median AQI 442004: Median AQI 442005: Median AQI 452006: Median AQI 442007: Median AQI 512008: Median AQI 452009: Median AQI 422010: Median AQI 472011: Median AQI 452012: Median AQI 452013: Median AQI 402014: Median AQI 442015: Median AQI 442016: Median AQI 422017: Median AQI 442018: Median AQI 392019: Median AQI 402020: Median AQI 342021: Median AQI 382022: Median AQI 412023: Median AQI 422024: Median AQI 402025: Median AQI 381984198919941999200420092014201920242025
  • 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
Ozone236100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025236218180000384997Ozone
20242322092120004050119Ozone
20232431994220004264115Ozone
2022245225200000415087Ozone
20212422152610003851105Ozone
202023623510000344458Ozone
2019221202190000405077Ozone
20182352023210003954133Ozone
20172411895200004464100Ozone
20162131664160004271133Ozone
20152121535810004471122Ozone
20142091733330004464122Ozone
2013198167310000406197Ozone
201219614241103004587192Ozone
20112071425483004590182Ozone
201021312872103004787169Ozone
20092141684420004261105Ozone
200820612761162004593159Ozone
2007214106862020051101187Ozone
2006213134581830044100185Ozone
2005212133561850045105179Ozone
200420514149141004493179Ozone
20032031404992304497217Ozone
20022071075927122050140207Ozone
2001212137491790046112179Ozone
2000213134462841045115207Ozone
1999213936430215061159208Ozone
1998210915535263061161208Ozone
19972061045830122050140206Ozone
1996207108692550049112172Ozone
19952071036331100051129190Ozone
1994191119482130047101161Ozone
1993202965833114058136210Ozone
1992204129571431044100212Ozone
19912091035733160051140197Ozone
1990326227702531039100208Ozone
198933325654212003490156Ozone
198828616951351714046161234Ozone
19873352155934216042140216Ozone
19863542256940191041129204Ozone
19852511425835151045133209Ozone
1984605820000244354Ozone

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 Maryland with a similar median AQI in 2025

All monitored counties in Maryland

Source: U.S. EPA AirData, “Annual AQI by County” files for 1984–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem