EnviroNearby

Blair County, Pennsylvania air quality history

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

77%
Good days in 2025
40
Median daily AQI, 2025
1
Days above 100 in 2025
363
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Blair, Pennsylvania on 363 days. 279 of those days (77%) were in the Good range, and the median daily AQI was 40. That median is about the same as the typical monitored county in Pennsylvania (median 40 across 38 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 215 days. Across the years with fuller monitoring, the share of Good days fell: an average of 81% in 1981–1983 versus 74% in 2023–2025.

Years with fewer than 120 monitored days (1980) 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 43 of 59 days1980: Moderate 7 of 59 days1980: Unhealthy for Sensitive Groups 6 of 59 days1980: Unhealthy 3 of 59 days19801981: Good 268 of 314 days1981: Moderate 30 of 314 days1981: Unhealthy for Sensitive Groups 13 of 314 days1981: Unhealthy 3 of 314 days1982: Good 289 of 362 days1982: Moderate 52 of 362 days1982: Unhealthy for Sensitive Groups 16 of 362 days1982: Unhealthy 5 of 362 days1983: Good 285 of 365 days1983: Moderate 51 of 365 days1983: Unhealthy for Sensitive Groups 17 of 365 days1983: Unhealthy 12 of 365 days1984: Good 310 of 363 days1984: Moderate 39 of 363 days1984: Unhealthy for Sensitive Groups 12 of 363 days1984: Unhealthy 1 of 363 days1984: Very Unhealthy 1 of 363 days1985: Good 276 of 358 days1985: Moderate 60 of 358 days1985: Unhealthy for Sensitive Groups 18 of 358 days1985: Unhealthy 4 of 358 days19851986: Good 286 of 355 days1986: Moderate 48 of 355 days1986: Unhealthy for Sensitive Groups 19 of 355 days1986: Unhealthy 2 of 355 days1987: Good 268 of 352 days1987: Moderate 58 of 352 days1987: Unhealthy for Sensitive Groups 18 of 352 days1987: Unhealthy 7 of 352 days1987: Very Unhealthy 1 of 352 days1988: Good 271 of 358 days1988: Moderate 36 of 358 days1988: Unhealthy for Sensitive Groups 22 of 358 days1988: Unhealthy 21 of 358 days1988: Very Unhealthy 8 of 358 days1989: Good 307 of 362 days1989: Moderate 50 of 362 days1989: Unhealthy for Sensitive Groups 3 of 362 days1989: Unhealthy 2 of 362 days1990: Good 301 of 356 days1990: Moderate 40 of 356 days1990: Unhealthy for Sensitive Groups 12 of 356 days1990: Unhealthy 3 of 356 days19901991: Good 270 of 365 days1991: Moderate 65 of 365 days1991: Unhealthy for Sensitive Groups 22 of 365 days1991: Unhealthy 8 of 365 days1992: Good 315 of 363 days1992: Moderate 39 of 363 days1992: Unhealthy for Sensitive Groups 7 of 363 days1992: Unhealthy 2 of 363 days1993: Good 291 of 365 days1993: Moderate 53 of 365 days1993: Unhealthy for Sensitive Groups 17 of 365 days1993: Unhealthy 4 of 365 days1994: Good 268 of 365 days1994: Moderate 77 of 365 days1994: Unhealthy for Sensitive Groups 14 of 365 days1994: Unhealthy 6 of 365 days1995: Good 293 of 362 days1995: Moderate 48 of 362 days1995: Unhealthy for Sensitive Groups 14 of 362 days1995: Unhealthy 7 of 362 days19951996: Good 298 of 366 days1996: Moderate 51 of 366 days1996: Unhealthy for Sensitive Groups 15 of 366 days1996: Unhealthy 2 of 366 days1997: Good 296 of 365 days1997: Moderate 48 of 365 days1997: Unhealthy for Sensitive Groups 15 of 365 days1997: Unhealthy 5 of 365 days1997: Very Unhealthy 1 of 365 days1998: Good 268 of 365 days1998: Moderate 64 of 365 days1998: Unhealthy for Sensitive Groups 17 of 365 days1998: Unhealthy 16 of 365 days1999: Good 270 of 363 days1999: Moderate 67 of 363 days1999: Unhealthy for Sensitive Groups 20 of 363 days1999: Unhealthy 6 of 363 days2000: Good 319 of 366 days2000: Moderate 36 of 366 days2000: Unhealthy for Sensitive Groups 9 of 366 days2000: Unhealthy 2 of 366 days20002001: Good 284 of 365 days2001: Moderate 58 of 365 days2001: Unhealthy for Sensitive Groups 20 of 365 days2001: Unhealthy 3 of 365 days2002: Good 283 of 365 days2002: Moderate 47 of 365 days2002: Unhealthy for Sensitive Groups 27 of 365 days2002: Unhealthy 7 of 365 days2002: Very Unhealthy 1 of 365 days2003: Good 307 of 365 days2003: Moderate 48 of 365 days2003: Unhealthy for Sensitive Groups 7 of 365 days2003: Unhealthy 3 of 365 days2004: Good 305 of 366 days2004: Moderate 54 of 366 days2004: Unhealthy for Sensitive Groups 7 of 366 days2005: Good 299 of 365 days2005: Moderate 54 of 365 days2005: Unhealthy for Sensitive Groups 12 of 365 days20052006: Good 313 of 365 days2006: Moderate 48 of 365 days2006: Unhealthy for Sensitive Groups 4 of 365 days2007: Good 315 of 365 days2007: Moderate 46 of 365 days2007: Unhealthy for Sensitive Groups 4 of 365 days2008: Good 307 of 365 days2008: Moderate 53 of 365 days2008: Unhealthy for Sensitive Groups 5 of 365 days2009: Good 338 of 365 days2009: Moderate 27 of 365 days2010: Good 285 of 365 days2010: Moderate 71 of 365 days2010: Unhealthy for Sensitive Groups 9 of 365 days20102011: Good 146 of 365 days2011: Moderate 210 of 365 days2011: Unhealthy for Sensitive Groups 8 of 365 days2011: Unhealthy 1 of 365 days2012: Good 139 of 365 days2012: Moderate 212 of 365 days2012: Unhealthy for Sensitive Groups 12 of 365 days2012: Unhealthy 2 of 365 days2013: Good 120 of 365 days2013: Moderate 242 of 365 days2013: Unhealthy for Sensitive Groups 3 of 365 days2014: Good 151 of 365 days2014: Moderate 212 of 365 days2014: Unhealthy for Sensitive Groups 2 of 365 days2015: Good 168 of 365 days2015: Moderate 195 of 365 days2015: Unhealthy for Sensitive Groups 2 of 365 days20152016: Good 230 of 366 days2016: Moderate 134 of 366 days2016: Unhealthy for Sensitive Groups 2 of 366 days2017: Good 223 of 362 days2017: Moderate 139 of 362 days2018: Good 244 of 359 days2018: Moderate 114 of 359 days2018: Unhealthy for Sensitive Groups 1 of 359 days2019: Good 220 of 352 days2019: Moderate 132 of 352 days2020: Good 262 of 360 days2020: Moderate 98 of 360 days20202021: Good 206 of 336 days2021: Moderate 128 of 336 days2021: Unhealthy for Sensitive Groups 2 of 336 days2022: Good 234 of 363 days2022: Moderate 129 of 363 days2023: Good 229 of 358 days2023: Moderate 123 of 358 days2023: Unhealthy for Sensitive Groups 1 of 358 days2023: Unhealthy 4 of 358 days2023: Very Unhealthy 1 of 358 days2024: Good 296 of 366 days2024: Moderate 70 of 366 days2025: Good 279 of 363 days2025: Moderate 83 of 363 days2025: Unhealthy for Sensitive Groups 1 of 363 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 1151981: 90th percentile AQI 651982: 90th percentile AQI 841983: 90th percentile AQI 901984: 90th percentile AQI 611985: 90th percentile AQI 771986: 90th percentile AQI 741987: 90th percentile AQI 931988: 90th percentile AQI 1431989: 90th percentile AQI 641990: 90th percentile AQI 711991: 90th percentile AQI 901992: 90th percentile AQI 611993: 90th percentile AQI 771994: 90th percentile AQI 871995: 90th percentile AQI 801996: 90th percentile AQI 711997: 90th percentile AQI 771998: 90th percentile AQI 1001999: 90th percentile AQI 842000: 90th percentile AQI 582001: 90th percentile AQI 872002: 90th percentile AQI 1002003: 90th percentile AQI 612004: 90th percentile AQI 612005: 90th percentile AQI 722006: 90th percentile AQI 612007: 90th percentile AQI 582008: 90th percentile AQI 642009: 90th percentile AQI 482010: 90th percentile AQI 712011: 90th percentile AQI 762012: 90th percentile AQI 772013: 90th percentile AQI 712014: 90th percentile AQI 682015: 90th percentile AQI 692016: 90th percentile AQI 642017: 90th percentile AQI 622018: 90th percentile AQI 632019: 90th percentile AQI 642020: 90th percentile AQI 602021: 90th percentile AQI 642022: 90th percentile AQI 592023: 90th percentile AQI 672024: 90th percentile AQI 582025: 90th percentile AQI 601980: Median AQI 291981: Median AQI 351982: Median AQI 371983: Median AQI 351984: Median AQI 341985: Median AQI 381986: Median AQI 311987: Median AQI 341988: Median AQI 351989: Median AQI 311990: Median AQI 311991: Median AQI 391992: Median AQI 341993: Median AQI 351994: Median AQI 391995: Median AQI 341996: Median AQI 351997: Median AQI 361998: Median AQI 361999: Median AQI 362000: Median AQI 352001: Median AQI 382002: Median AQI 362003: Median AQI 352004: Median AQI 342005: Median AQI 362006: Median AQI 342007: Median AQI 352008: Median AQI 332009: Median AQI 272010: Median AQI 342011: Median AQI 532012: Median AQI 542013: Median AQI 542014: Median AQI 532015: Median AQI 522016: Median AQI 442017: Median AQI 452018: Median AQI 422019: Median AQI 462020: Median AQI 432021: Median AQI 452022: Median AQI 442023: Median AQI 432024: Median AQI 372025: Median AQI 401980198519901995200020052010201520202025
  • 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
Ozone21559%
Fine particles (PM2.5)14841%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253632798310004060115Ozone
20243662967000003758100Ozone
202335822912314104367213PM2.5
20223632341290000445997PM2.5
202133620612820004564120PM2.5
2020360262980000436087PM2.5
20193522201320000466493PM2.5
201835924411410004263132Ozone
20173622231390000456289PM2.5
201636623013420004464122PM2.5
201536516819520005269108PM2.5
201436515121220005368108PM2.5
201336512024230005471115PM2.5
2012365139212122005477161PM2.5
201136514621081005376159PM2.5
20103652857190003471147Ozone
2009365338270000274897Ozone
20083653075350003364140Ozone
20073653154640003558122Ozone
20063653134840003461133Ozone
200536529954120003672150Ozone
20043663055470003461115Ozone
20033653074873003561197Ozone
2002365283472771036100203Ozone
200136528458203003887177Ozone
20003663193692003558177Ozone
199936327067206003684192Ozone
19983652686417160036100187Ozone
199736529648155103677203Ozone
199636629851152003571185Ozone
199536229348147003480179Ozone
199436526877146003987187Ozone
199336529153174003577169Ozone
19923633153972003461159Ozone
199136527065228003990179Ozone
199035630140123003171172Ozone
19893623075032003164172Ozone
19883582713622218035143224Ozone
198735226858187103493202Ozone
198635528648192003174161Ozone
198535827660184003877187Ozone
198436331039121103461284Ozone
1983365285511712003590192Ozone
198236228952165003784182Ozone
198131426830133003565161Ozone
198059437630029115177Ozone

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