EnviroNearby

Dauphin County, Pennsylvania air quality history

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

62%
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 Dauphin, Pennsylvania on 365 days. 228 of those days (62%) were in the Good range, and the median daily AQI was 44. 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 202 days. Across the years with fuller monitoring, the share of Good days fell: an average of 65% in 1980–1982 versus 55% 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 213 of 356 days1980: Moderate 109 of 356 days1980: Unhealthy for Sensitive Groups 26 of 356 days1980: Unhealthy 8 of 356 days19801981: Good 251 of 340 days1981: Moderate 64 of 340 days1981: Unhealthy for Sensitive Groups 19 of 340 days1981: Unhealthy 4 of 340 days1981: Very Unhealthy 2 of 340 days1982: Good 223 of 365 days1982: Moderate 95 of 365 days1982: Unhealthy for Sensitive Groups 33 of 365 days1982: Unhealthy 14 of 365 days1983: Good 236 of 365 days1983: Moderate 62 of 365 days1983: Unhealthy for Sensitive Groups 32 of 365 days1983: Unhealthy 28 of 365 days1983: Very Unhealthy 7 of 365 days1984: Good 268 of 366 days1984: Moderate 62 of 366 days1984: Unhealthy for Sensitive Groups 30 of 366 days1984: Unhealthy 6 of 366 days1985: Good 239 of 365 days1985: Moderate 89 of 365 days1985: Unhealthy for Sensitive Groups 28 of 365 days1985: Unhealthy 9 of 365 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 220 of 365 days1987: Moderate 102 of 365 days1987: Unhealthy for Sensitive Groups 25 of 365 days1987: Unhealthy 14 of 365 days1987: Very Unhealthy 4 of 365 days1988: Good 249 of 366 days1988: Moderate 65 of 366 days1988: Unhealthy for Sensitive Groups 22 of 366 days1988: Unhealthy 23 of 366 days1988: Very Unhealthy 7 of 366 days1989: Good 263 of 365 days1989: Moderate 75 of 365 days1989: Unhealthy for Sensitive Groups 18 of 365 days1989: Unhealthy 9 of 365 days1990: Good 271 of 365 days1990: Moderate 67 of 365 days1990: Unhealthy for Sensitive Groups 18 of 365 days1990: Unhealthy 7 of 365 days1990: Very Unhealthy 2 of 365 days19901991: Good 241 of 365 days1991: Moderate 74 of 365 days1991: Unhealthy for Sensitive Groups 32 of 365 days1991: Unhealthy 18 of 365 days1992: Good 290 of 366 days1992: Moderate 60 of 366 days1992: Unhealthy for Sensitive Groups 15 of 366 days1992: Unhealthy 1 of 366 days1993: Good 264 of 362 days1993: Moderate 60 of 362 days1993: Unhealthy for Sensitive Groups 25 of 362 days1993: Unhealthy 13 of 362 days1994: Good 227 of 361 days1994: Moderate 98 of 361 days1994: Unhealthy for Sensitive Groups 27 of 361 days1994: Unhealthy 7 of 361 days1994: Very Unhealthy 2 of 361 days1995: Good 281 of 364 days1995: Moderate 50 of 364 days1995: Unhealthy for Sensitive Groups 25 of 364 days1995: Unhealthy 7 of 364 days1995: Very Unhealthy 1 of 364 days19951996: Good 272 of 366 days1996: Moderate 67 of 366 days1996: Unhealthy for Sensitive Groups 24 of 366 days1996: Unhealthy 3 of 366 days1997: Good 290 of 365 days1997: Moderate 49 of 365 days1997: Unhealthy for Sensitive Groups 17 of 365 days1997: Unhealthy 9 of 365 days1998: Good 251 of 365 days1998: Moderate 61 of 365 days1998: Unhealthy for Sensitive Groups 32 of 365 days1998: Unhealthy 20 of 365 days1998: Very Unhealthy 1 of 365 days1999: Good 159 of 365 days1999: Moderate 161 of 365 days1999: Unhealthy for Sensitive Groups 29 of 365 days1999: Unhealthy 14 of 365 days1999: Very Unhealthy 2 of 365 days2000: Good 146 of 366 days2000: Moderate 192 of 366 days2000: Unhealthy for Sensitive Groups 21 of 366 days2000: Unhealthy 7 of 366 days20002001: Good 96 of 365 days2001: Moderate 211 of 365 days2001: Unhealthy for Sensitive Groups 44 of 365 days2001: Unhealthy 14 of 365 days2002: Good 103 of 365 days2002: Moderate 220 of 365 days2002: Unhealthy for Sensitive Groups 25 of 365 days2002: Unhealthy 15 of 365 days2002: Very Unhealthy 2 of 365 days2003: Good 104 of 365 days2003: Moderate 236 of 365 days2003: Unhealthy for Sensitive Groups 22 of 365 days2003: Unhealthy 2 of 365 days2003: Very Unhealthy 1 of 365 days2004: Good 100 of 366 days2004: Moderate 248 of 366 days2004: Unhealthy for Sensitive Groups 17 of 366 days2004: Unhealthy 1 of 366 days2005: Good 101 of 365 days2005: Moderate 232 of 365 days2005: Unhealthy for Sensitive Groups 28 of 365 days2005: Unhealthy 4 of 365 days20052006: Good 134 of 365 days2006: Moderate 213 of 365 days2006: Unhealthy for Sensitive Groups 17 of 365 days2006: Unhealthy 1 of 365 days2007: Good 125 of 365 days2007: Moderate 207 of 365 days2007: Unhealthy for Sensitive Groups 32 of 365 days2007: Unhealthy 1 of 365 days2008: Good 128 of 366 days2008: Moderate 217 of 366 days2008: Unhealthy for Sensitive Groups 20 of 366 days2008: Unhealthy 1 of 366 days2009: Good 152 of 364 days2009: Moderate 205 of 364 days2009: Unhealthy for Sensitive Groups 7 of 364 days2010: Good 165 of 365 days2010: Moderate 188 of 365 days2010: Unhealthy for Sensitive Groups 11 of 365 days2010: Unhealthy 1 of 365 days20102011: Good 147 of 365 days2011: Moderate 204 of 365 days2011: Unhealthy for Sensitive Groups 14 of 365 days2012: Good 144 of 365 days2012: Moderate 212 of 365 days2012: Unhealthy for Sensitive Groups 9 of 365 days2013: Good 139 of 365 days2013: Moderate 217 of 365 days2013: Unhealthy for Sensitive Groups 9 of 365 days2014: Good 149 of 365 days2014: Moderate 212 of 365 days2014: Unhealthy for Sensitive Groups 4 of 365 days2015: Good 120 of 365 days2015: Moderate 237 of 365 days2015: Unhealthy for Sensitive Groups 8 of 365 days20152016: Good 188 of 366 days2016: Moderate 172 of 366 days2016: Unhealthy for Sensitive Groups 6 of 366 days2017: Good 204 of 365 days2017: Moderate 160 of 365 days2017: Unhealthy for Sensitive Groups 1 of 365 days2018: Good 222 of 365 days2018: Moderate 142 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days2019: Good 232 of 365 days2019: Moderate 129 of 365 days2019: Unhealthy for Sensitive Groups 3 of 365 days2019: Unhealthy 1 of 365 days2020: Good 219 of 366 days2020: Moderate 144 of 366 days2020: Unhealthy for Sensitive Groups 3 of 366 days20202021: Good 155 of 359 days2021: Moderate 202 of 359 days2021: Unhealthy for Sensitive Groups 2 of 359 days2022: Good 198 of 365 days2022: Moderate 164 of 365 days2022: Unhealthy for Sensitive Groups 3 of 365 days2023: Good 169 of 365 days2023: Moderate 184 of 365 days2023: Unhealthy for Sensitive Groups 7 of 365 days2023: Unhealthy 3 of 365 days2023: Very Unhealthy 2 of 365 days2024: Good 206 of 366 days2024: Moderate 158 of 366 days2024: Unhealthy for Sensitive Groups 2 of 366 days2025: Good 228 of 365 days2025: Moderate 136 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 year0501001501980: 90th percentile AQI 971981: 90th percentile AQI 801982: 90th percentile AQI 1151983: 90th percentile AQI 1501984: 90th percentile AQI 1001985: 90th percentile AQI 1051986: 90th percentile AQI 841987: 90th percentile AQI 1151988: 90th percentile AQI 1361989: 90th percentile AQI 931990: 90th percentile AQI 931991: 90th percentile AQI 1121992: 90th percentile AQI 671993: 90th percentile AQI 1011994: 90th percentile AQI 1001995: 90th percentile AQI 971996: 90th percentile AQI 801997: 90th percentile AQI 871998: 90th percentile AQI 1221999: 90th percentile AQI 1082000: 90th percentile AQI 972001: 90th percentile AQI 1222002: 90th percentile AQI 1082003: 90th percentile AQI 942004: 90th percentile AQI 902005: 90th percentile AQI 972006: 90th percentile AQI 902007: 90th percentile AQI 972008: 90th percentile AQI 872009: 90th percentile AQI 772010: 90th percentile AQI 842011: 90th percentile AQI 802012: 90th percentile AQI 812013: 90th percentile AQI 792014: 90th percentile AQI 752015: 90th percentile AQI 772016: 90th percentile AQI 702017: 90th percentile AQI 652018: 90th percentile AQI 692019: 90th percentile AQI 672020: 90th percentile AQI 652021: 90th percentile AQI 712022: 90th percentile AQI 672023: 90th percentile AQI 792024: 90th percentile AQI 702025: 90th percentile AQI 651980: Median AQI 451981: Median AQI 391982: Median AQI 441983: Median AQI 431984: Median AQI 411985: Median AQI 441986: Median AQI 441987: Median AQI 441988: Median AQI 431989: Median AQI 411990: Median AQI 411991: Median AQI 421992: Median AQI 381993: Median AQI 381994: Median AQI 431995: Median AQI 391996: Median AQI 411997: Median AQI 391998: Median AQI 411999: Median AQI 542000: Median AQI 552001: Median AQI 632002: Median AQI 582003: Median AQI 612004: Median AQI 602005: Median AQI 612006: Median AQI 572007: Median AQI 582008: Median AQI 552009: Median AQI 542010: Median AQI 532011: Median AQI 552012: Median AQI 542013: Median AQI 552014: Median AQI 542015: Median AQI 562016: Median AQI 502017: Median AQI 472018: Median AQI 442019: Median AQI 442020: Median AQI 462021: Median AQI 522022: Median AQI 482023: Median AQI 522024: Median AQI 482025: Median AQI 441980198519901995200020052010201520202025
  • 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)20255%
Ozone16345%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536522813610004465101PM2.5
202436620615820004870105PM2.5
202336516918473205279255PM2.5
202236519816430004867127PM2.5
202135915520220005271127PM2.5
202036621914430004665116PM2.5
201936523212931004467161PM2.5
201836522214210004469108PM2.5
201736520416010004765110PM2.5
201636618817260005070115PM2.5
201536512023780005677124PM2.5
201436514921240005475123PM2.5
201336513921790005579139PM2.5
201236514421290005481129PM2.5
2011365147204140005580150PM2.5
2010365165188111005384154PM2.5
200936415220570005477118PM2.5
2008366128217201005587174PM2.5
2007365125207321005897151PM2.5
2006365134213171005790156PM2.5
2005365101232284006197174PM2.5
2004366100248171006090151PM2.5
2003365104236222106194203PM2.5
200236510322025152058108216PM2.5
20013659621144140063122182PM2.5
2000366146192217005597190PM2.5
199936515916129142054108210PM2.5
19983652516132201041122202NO2
199736529049179003987200NO2
199636627267243004180174NO2
199536428150257103997201NO2
1994361227982772043100208NO2
19933622646025130038101200Ozone
199236629060151003867179Ozone
19913652417432180042112195Ozone
199036527167187204193212Ozone
198936526375189004193169NO2
19883662496522237043136221Ozone
198736522010225144044115218Ozone
198636523996228004484195Ozone
1985365239892890044105185Ozone
1984366268623060041100200Ozone
19833652366232287043150249Ozone
19823652239533140044115195Ozone
198134025164194203980235NO2
1980356213109268004597195NO2

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