EnviroNearby

Tioga County, Pennsylvania air quality history

Daily Air Quality Index summaries from EPA monitors in Tioga, Pennsylvania, 1999–2025.

82%
Good days in 2025
39
Median daily AQI, 2025
2
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Tioga, Pennsylvania on 364 days. 299 of those days (82%) were in the Good range, and the median daily AQI was 39. 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 259 days. Across the years with fuller monitoring, the share of Good days rose: an average of 65% in 1999–2001 versus 84% 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%1999: Good 88 of 143 days1999: Moderate 37 of 143 days1999: Unhealthy for Sensitive Groups 17 of 143 days1999: Unhealthy 1 of 143 days19992000: Good 161 of 214 days2000: Moderate 39 of 214 days2000: Unhealthy for Sensitive Groups 12 of 214 days2000: Unhealthy 2 of 214 days2001: Good 126 of 212 days2001: Moderate 55 of 212 days2001: Unhealthy for Sensitive Groups 29 of 212 days2001: Unhealthy 2 of 212 days20012002: Good 127 of 213 days2002: Moderate 51 of 213 days2002: Unhealthy for Sensitive Groups 27 of 213 days2002: Unhealthy 8 of 213 days2003: Good 133 of 197 days2003: Moderate 54 of 197 days2003: Unhealthy for Sensitive Groups 8 of 197 days2003: Unhealthy 2 of 197 days20032004: Good 160 of 205 days2004: Moderate 40 of 205 days2004: Unhealthy for Sensitive Groups 5 of 205 days2005: Good 140 of 211 days2005: Moderate 57 of 211 days2005: Unhealthy for Sensitive Groups 14 of 211 days20052006: Good 166 of 214 days2006: Moderate 44 of 214 days2006: Unhealthy for Sensitive Groups 4 of 214 days2007: Good 156 of 207 days2007: Moderate 44 of 207 days2007: Unhealthy for Sensitive Groups 7 of 207 days20072008: Good 163 of 195 days2008: Moderate 27 of 195 days2008: Unhealthy for Sensitive Groups 5 of 195 days2009: Good 182 of 199 days2009: Moderate 17 of 199 days20092010: Good 149 of 214 days2010: Moderate 55 of 214 days2010: Unhealthy for Sensitive Groups 10 of 214 days2011: Good 249 of 297 days2011: Moderate 46 of 297 days2011: Unhealthy for Sensitive Groups 2 of 297 days20112012: Good 294 of 345 days2012: Moderate 47 of 345 days2012: Unhealthy for Sensitive Groups 4 of 345 days2013: Good 326 of 365 days2013: Moderate 38 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days20132014: Good 326 of 362 days2014: Moderate 36 of 362 days2015: Good 224 of 365 days2015: Moderate 141 of 365 days20152016: Good 280 of 366 days2016: Moderate 84 of 366 days2016: Unhealthy for Sensitive Groups 2 of 366 days2017: Good 150 of 363 days2017: Moderate 213 of 363 days20172018: Good 286 of 347 days2018: Moderate 61 of 347 days2019: Good 317 of 361 days2019: Moderate 44 of 361 days20192020: Good 298 of 352 days2020: Moderate 54 of 352 days2021: Good 274 of 350 days2021: Moderate 75 of 350 days2021: Unhealthy for Sensitive Groups 1 of 350 days20212022: Good 248 of 302 days2022: Moderate 54 of 302 days2023: Good 254 of 304 days2023: Moderate 50 of 304 days20232024: Good 316 of 362 days2024: Moderate 46 of 362 days2025: Good 299 of 364 days2025: Moderate 63 of 364 days2025: Unhealthy for Sensitive Groups 2 of 364 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 year0501001501999: 90th percentile AQI 1152000: 90th percentile AQI 842001: 90th percentile AQI 1152002: 90th percentile AQI 1222003: 90th percentile AQI 872004: 90th percentile AQI 672005: 90th percentile AQI 932006: 90th percentile AQI 672007: 90th percentile AQI 742008: 90th percentile AQI 712009: 90th percentile AQI 502010: 90th percentile AQI 802011: 90th percentile AQI 582012: 90th percentile AQI 612013: 90th percentile AQI 512014: 90th percentile AQI 502015: 90th percentile AQI 642016: 90th percentile AQI 582017: 90th percentile AQI 632018: 90th percentile AQI 552019: 90th percentile AQI 522020: 90th percentile AQI 532021: 90th percentile AQI 582022: 90th percentile AQI 542023: 90th percentile AQI 592024: 90th percentile AQI 522025: 90th percentile AQI 561999: Median AQI 472000: Median AQI 442001: Median AQI 482002: Median AQI 472003: Median AQI 442004: Median AQI 422005: Median AQI 462006: Median AQI 422007: Median AQI 432008: Median AQI 412009: Median AQI 382010: Median AQI 442011: Median AQI 402012: Median AQI 362013: Median AQI 362014: Median AQI 382015: Median AQI 442016: Median AQI 412017: Median AQI 532018: Median AQI 372019: Median AQI 372020: Median AQI 392021: Median AQI 382022: Median AQI 392023: Median AQI 412024: Median AQI 362025: Median AQI 3919992001200320052007200920112013201520172019202120232025
  • 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
Ozone25971%
Fine particles (PM2.5)10529%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253642996320003956127Ozone
2024362316460000365284Ozone
20233042545000004159100Ozone
2022302248540000395477Ozone
20213502747510003858131Ozone
2020352298540000395381Ozone
2019361317440000375277Ozone
2018347286610000375597Ozone
20173631502130000536384PM2.5
20163662808420004158112Ozone
20153652241410000446490PM2.5
2014362326360000385074Ozone
20133653263810003651112Ozone
20123452944740003661140Ozone
20112972494620004058112Ozone
201021414955100004480140Ozone
2009199182170000385090Ozone
20081951632750004171150Ozone
20072071564470004374126Ozone
20062141664440004267115Ozone
200521114057140004693143Ozone
20042051604050004267136Ozone
20031971335482004487185Ozone
2002213127512780047122200Ozone
2001212126552920048115151Ozone
200021416139122004484174Ozone
199914388371710047115151Ozone

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 1999–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem