EnviroNearby

York County, Pennsylvania air quality history

Daily Air Quality Index summaries from EPA monitors in York, Pennsylvania, 1980–2025.

59%
Good days in 2025
45
Median daily AQI, 2025
3
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 York, Pennsylvania on 365 days. 217 of those days (59%) were in the Good range, and the median daily AQI was 45. That median is higher than the typical monitored county in Pennsylvania (median 40 across 38 counties), and higher than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 188 days. Across the years with fuller monitoring, the share of Good days fell: an average of 64% in 1980–1982 versus 60% 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%1980: Good 211 of 354 days1980: Moderate 87 of 354 days1980: Unhealthy for Sensitive Groups 29 of 354 days1980: Unhealthy 22 of 354 days1980: Very Unhealthy 5 of 354 days19801981: Good 223 of 332 days1981: Moderate 94 of 332 days1981: Unhealthy for Sensitive Groups 9 of 332 days1981: Unhealthy 5 of 332 days1981: Very Unhealthy 1 of 332 days1982: Good 229 of 356 days1982: Moderate 98 of 356 days1982: Unhealthy for Sensitive Groups 24 of 356 days1982: Unhealthy 5 of 356 days1983: Good 222 of 365 days1983: Moderate 90 of 365 days1983: Unhealthy for Sensitive Groups 25 of 365 days1983: Unhealthy 23 of 365 days1983: Very Unhealthy 5 of 365 days1984: Good 263 of 366 days1984: Moderate 71 of 366 days1984: Unhealthy for Sensitive Groups 26 of 366 days1984: Unhealthy 5 of 366 days1984: Very Unhealthy 1 of 366 days1985: Good 224 of 364 days1985: Moderate 100 of 364 days1985: Unhealthy for Sensitive Groups 24 of 364 days1985: Unhealthy 16 of 364 days19851986: Good 239 of 365 days1986: Moderate 96 of 365 days1986: Unhealthy for Sensitive Groups 22 of 365 days1986: Unhealthy 8 of 365 days1987: Good 229 of 364 days1987: Moderate 102 of 364 days1987: Unhealthy for Sensitive Groups 19 of 364 days1987: Unhealthy 14 of 364 days1988: Good 249 of 365 days1988: Moderate 63 of 365 days1988: Unhealthy for Sensitive Groups 20 of 365 days1988: Unhealthy 28 of 365 days1988: Very Unhealthy 5 of 365 days1989: Good 272 of 365 days1989: Moderate 70 of 365 days1989: Unhealthy for Sensitive Groups 19 of 365 days1989: Unhealthy 4 of 365 days1990: Good 257 of 364 days1990: Moderate 78 of 364 days1990: Unhealthy for Sensitive Groups 21 of 364 days1990: Unhealthy 6 of 364 days1990: Very Unhealthy 2 of 364 days19901991: Good 246 of 365 days1991: Moderate 70 of 365 days1991: Unhealthy for Sensitive Groups 33 of 365 days1991: Unhealthy 15 of 365 days1991: Very Unhealthy 1 of 365 days1992: Good 284 of 366 days1992: Moderate 62 of 366 days1992: Unhealthy for Sensitive Groups 19 of 366 days1992: Unhealthy 1 of 366 days1993: Good 256 of 364 days1993: Moderate 78 of 364 days1993: Unhealthy for Sensitive Groups 22 of 364 days1993: Unhealthy 8 of 364 days1994: Good 246 of 364 days1994: Moderate 88 of 364 days1994: Unhealthy for Sensitive Groups 28 of 364 days1994: Unhealthy 1 of 364 days1994: Very Unhealthy 1 of 364 days1995: Good 277 of 364 days1995: Moderate 61 of 364 days1995: Unhealthy for Sensitive Groups 21 of 364 days1995: Unhealthy 5 of 364 days19951996: Good 287 of 365 days1996: Moderate 62 of 365 days1996: Unhealthy for Sensitive Groups 14 of 365 days1996: Unhealthy 2 of 365 days1997: Good 273 of 365 days1997: Moderate 53 of 365 days1997: Unhealthy for Sensitive Groups 28 of 365 days1997: Unhealthy 11 of 365 days1998: Good 264 of 365 days1998: Moderate 54 of 365 days1998: Unhealthy for Sensitive Groups 33 of 365 days1998: Unhealthy 14 of 365 days1999: Good 223 of 365 days1999: Moderate 110 of 365 days1999: Unhealthy for Sensitive Groups 22 of 365 days1999: Unhealthy 9 of 365 days1999: Very Unhealthy 1 of 365 days2000: Good 210 of 366 days2000: Moderate 129 of 366 days2000: Unhealthy for Sensitive Groups 22 of 366 days2000: Unhealthy 4 of 366 days2000: Very Unhealthy 1 of 366 days20002001: Good 194 of 365 days2001: Moderate 126 of 365 days2001: Unhealthy for Sensitive Groups 38 of 365 days2001: Unhealthy 7 of 365 days2002: Good 199 of 365 days2002: Moderate 118 of 365 days2002: Unhealthy for Sensitive Groups 33 of 365 days2002: Unhealthy 12 of 365 days2002: Very Unhealthy 3 of 365 days2003: Good 224 of 364 days2003: Moderate 112 of 364 days2003: Unhealthy for Sensitive Groups 25 of 364 days2003: Unhealthy 2 of 364 days2003: Very Unhealthy 1 of 364 days2004: Good 220 of 366 days2004: Moderate 130 of 366 days2004: Unhealthy for Sensitive Groups 14 of 366 days2004: Unhealthy 2 of 366 days2005: Good 193 of 365 days2005: Moderate 134 of 365 days2005: Unhealthy for Sensitive Groups 31 of 365 days2005: Unhealthy 7 of 365 days20052006: Good 235 of 365 days2006: Moderate 120 of 365 days2006: Unhealthy for Sensitive Groups 9 of 365 days2006: Unhealthy 1 of 365 days2007: Good 204 of 365 days2007: Moderate 127 of 365 days2007: Unhealthy for Sensitive Groups 31 of 365 days2007: Unhealthy 3 of 365 days2008: Good 217 of 365 days2008: Moderate 124 of 365 days2008: Unhealthy for Sensitive Groups 22 of 365 days2008: Unhealthy 2 of 365 days2009: Good 130 of 365 days2009: Moderate 230 of 365 days2009: Unhealthy for Sensitive Groups 5 of 365 days2010: Good 139 of 365 days2010: Moderate 206 of 365 days2010: Unhealthy for Sensitive Groups 18 of 365 days2010: Unhealthy 2 of 365 days20102011: Good 97 of 365 days2011: Moderate 255 of 365 days2011: Unhealthy for Sensitive Groups 13 of 365 days2012: Good 120 of 366 days2012: Moderate 232 of 366 days2012: Unhealthy for Sensitive Groups 13 of 366 days2012: Unhealthy 1 of 366 days2013: Good 169 of 365 days2013: Moderate 190 of 365 days2013: Unhealthy for Sensitive Groups 6 of 365 days2014: Good 155 of 365 days2014: Moderate 209 of 365 days2014: Unhealthy for Sensitive Groups 1 of 365 days2015: Good 135 of 365 days2015: Moderate 221 of 365 days2015: Unhealthy for Sensitive Groups 9 of 365 days20152016: Good 176 of 366 days2016: Moderate 185 of 366 days2016: Unhealthy for Sensitive Groups 5 of 366 days2017: Good 198 of 365 days2017: Moderate 167 of 365 days2018: Good 206 of 365 days2018: Moderate 158 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days2019: Good 232 of 365 days2019: Moderate 133 of 365 days2020: Good 221 of 366 days2020: Moderate 145 of 366 days20202021: Good 168 of 357 days2021: Moderate 187 of 357 days2021: Unhealthy for Sensitive Groups 2 of 357 days2022: Good 205 of 365 days2022: Moderate 159 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days2023: Good 198 of 356 days2023: Moderate 150 of 356 days2023: Unhealthy for Sensitive Groups 4 of 356 days2023: Unhealthy 3 of 356 days2023: Very Unhealthy 1 of 356 days2024: Good 240 of 366 days2024: Moderate 125 of 366 days2024: Unhealthy for Sensitive Groups 1 of 366 days2025: Good 217 of 365 days2025: Moderate 145 of 365 days2025: Unhealthy for Sensitive Groups 3 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 year0501001501980: 90th percentile AQI 1431981: 90th percentile AQI 801982: 90th percentile AQI 951983: 90th percentile AQI 1151984: 90th percentile AQI 931985: 90th percentile AQI 1021986: 90th percentile AQI 971987: 90th percentile AQI 931988: 90th percentile AQI 1361989: 90th percentile AQI 841990: 90th percentile AQI 871991: 90th percentile AQI 1121992: 90th percentile AQI 771993: 90th percentile AQI 931994: 90th percentile AQI 871995: 90th percentile AQI 801996: 90th percentile AQI 741997: 90th percentile AQI 1051998: 90th percentile AQI 1081999: 90th percentile AQI 972000: 90th percentile AQI 892001: 90th percentile AQI 1082002: 90th percentile AQI 1082003: 90th percentile AQI 892004: 90th percentile AQI 882005: 90th percentile AQI 1012006: 90th percentile AQI 802007: 90th percentile AQI 1002008: 90th percentile AQI 872009: 90th percentile AQI 752010: 90th percentile AQI 902011: 90th percentile AQI 822012: 90th percentile AQI 832013: 90th percentile AQI 762014: 90th percentile AQI 712015: 90th percentile AQI 822016: 90th percentile AQI 702017: 90th percentile AQI 662018: 90th percentile AQI 642019: 90th percentile AQI 602020: 90th percentile AQI 622021: 90th percentile AQI 712022: 90th percentile AQI 642023: 90th percentile AQI 722024: 90th percentile AQI 672025: 90th percentile AQI 671980: Median AQI 441981: Median AQI 431982: Median AQI 441983: Median AQI 461984: Median AQI 421985: Median AQI 441986: Median AQI 431987: Median AQI 461988: Median AQI 421989: Median AQI 391990: Median AQI 411991: Median AQI 411992: Median AQI 391993: Median AQI 411994: Median AQI 421995: Median AQI 391996: Median AQI 391997: Median AQI 401998: Median AQI 391999: Median AQI 452000: Median AQI 462001: Median AQI 492002: Median AQI 472003: Median AQI 442004: Median AQI 462005: Median AQI 492006: Median AQI 442007: Median AQI 472008: Median AQI 432009: Median AQI 542010: Median AQI 562011: Median AQI 592012: Median AQI 562013: Median AQI 522014: Median AQI 522015: Median AQI 552016: Median AQI 512017: Median AQI 472018: Median AQI 452019: Median AQI 442020: Median AQI 462021: Median AQI 512022: Median AQI 472023: Median AQI 482024: Median AQI 442025: Median AQI 451980198519901995200020052010201520202025
  • 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)18852%
Ozone17648%
Nitrogen dioxide (NO₂)1<1%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536521714530004567116PM2.5
202436624012510004467101Ozone
202335619815043104872256PM2.5
202236520515910004764105PM2.5
202135716818720005171148PM2.5
20203662211450000466297PM2.5
20193652321330000446094PM2.5
201836520615810004564101PM2.5
20173651981670000476693PM2.5
201636617618550005170133PM2.5
201536513522190005582126PM2.5
201436515520910005271108PM2.5
201336516919060005276143PM2.5
2012366120232131005683166PM2.5
201136597255130005982147PM2.5
2010365139206182005690156PM2.5
200936513023050005475127PM2.5
2008365217124222004387177Ozone
20073652041273130047100164Ozone
200636523512091004480160NO2
20053651931343170049101179Ozone
2004366220130142004688153Ozone
2003364224112252104489202Ozone
200236519911833123047108219Ozone
20013651941263870049108169NO2
2000366210129224104689201NO2
1999365223110229104597205NO2
19983652645433140039108192NO2
19973652735328110040105192NO2
199636528762142003974156NO2
199536427761215003980164NO2
199436424688281104287202NO2
199336425678228004193185NO2
199236628462191003977177NO2
19913652467033151041112204NO2
199036425778216204187206NO2
198936527270194003984164NO2
19883652496320285042136225NO2
19873642291021914004693197NO2
198636523996228004397187NO2
198536422410024160044102195NO2
198436626371265104293209NO2
19833652229025235046115217NO2
198235622998245004495195NO2
19813322239495104380212NO2
19803542118729225044143208NO2

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 Pennsylvania with a similar median AQI in 2025

All monitored counties in Pennsylvania

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem