EnviroNearby

Monroe County, Pennsylvania air quality history

Daily Air Quality Index summaries from EPA monitors in Monroe, Pennsylvania, 1997–2025.

88%
Good days in 2025
36
Median daily AQI, 2025
2
Days above 100 in 2025
360
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Monroe, Pennsylvania on 360 days. 318 of those days (88%) were in the Good range, and the median daily AQI was 36. That median is lower than the typical monitored county in Pennsylvania (median 40 across 38 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 307 days. Across the years with fuller monitoring, the share of Good days rose: an average of 57% in 1998–2006 versus 91% in 2023–2025.

Years with fewer than 120 monitored days (1997) 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%1997: Good 48 of 96 days1997: Moderate 21 of 96 days1997: Unhealthy for Sensitive Groups 13 of 96 days1997: Unhealthy 13 of 96 days1997: Very Unhealthy 1 of 96 days19971998: Good 106 of 197 days1998: Moderate 51 of 197 days1998: Unhealthy for Sensitive Groups 29 of 197 days1998: Unhealthy 11 of 197 days1999: Good 62 of 152 days1999: Moderate 56 of 152 days1999: Unhealthy for Sensitive Groups 16 of 152 days1999: Unhealthy 16 of 152 days1999: Very Unhealthy 2 of 152 days19992006: Good 162 of 211 days2006: Moderate 42 of 211 days2006: Unhealthy for Sensitive Groups 7 of 211 days2007: Good 168 of 207 days2007: Moderate 32 of 207 days2007: Unhealthy for Sensitive Groups 6 of 207 days2007: Unhealthy 1 of 207 days20072008: Good 168 of 211 days2008: Moderate 37 of 211 days2008: Unhealthy for Sensitive Groups 4 of 211 days2008: Unhealthy 2 of 211 days2009: Good 159 of 167 days2009: Moderate 8 of 167 days20092010: Good 150 of 260 days2010: Moderate 99 of 260 days2010: Unhealthy for Sensitive Groups 11 of 260 days2011: Good 265 of 359 days2011: Moderate 94 of 359 days20112012: Good 229 of 365 days2012: Moderate 134 of 365 days2012: Unhealthy for Sensitive Groups 2 of 365 days2013: Good 200 of 365 days2013: Moderate 164 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days20132014: Good 212 of 364 days2014: Moderate 152 of 364 days2015: Good 243 of 364 days2015: Moderate 120 of 364 days2015: Unhealthy for Sensitive Groups 1 of 364 days20152016: Good 265 of 366 days2016: Moderate 98 of 366 days2016: Unhealthy for Sensitive Groups 3 of 366 days2017: Good 252 of 364 days2017: Moderate 112 of 364 days20172018: Good 309 of 355 days2018: Moderate 44 of 355 days2018: Unhealthy for Sensitive Groups 2 of 355 days2019: Good 340 of 349 days2019: Moderate 9 of 349 days20192020: Good 355 of 357 days2020: Moderate 2 of 357 days2021: Good 214 of 233 days2021: Moderate 19 of 233 days20212022: Good 184 of 202 days2022: Moderate 18 of 202 days2023: Good 270 of 294 days2023: Moderate 21 of 294 days2023: Unhealthy for Sensitive Groups 3 of 294 days20232024: Good 329 of 360 days2024: Moderate 30 of 360 days2024: Unhealthy for Sensitive Groups 1 of 360 days2025: Good 318 of 360 days2025: Moderate 40 of 360 days2025: Unhealthy for Sensitive Groups 2 of 360 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 year0501001502001997: 90th percentile AQI 1641998: 90th percentile AQI 1331999: 90th percentile AQI 1542006: 90th percentile AQI 712007: 90th percentile AQI 742008: 90th percentile AQI 672009: 90th percentile AQI 472010: 90th percentile AQI 842011: 90th percentile AQI 602012: 90th percentile AQI 662013: 90th percentile AQI 642014: 90th percentile AQI 622015: 90th percentile AQI 642016: 90th percentile AQI 612017: 90th percentile AQI 602018: 90th percentile AQI 542019: 90th percentile AQI 452020: 90th percentile AQI 442021: 90th percentile AQI 492022: 90th percentile AQI 492023: 90th percentile AQI 482024: 90th percentile AQI 492025: 90th percentile AQI 521997: Median AQI 511998: Median AQI 481999: Median AQI 612006: Median AQI 412007: Median AQI 392008: Median AQI 392009: Median AQI 342010: Median AQI 452011: Median AQI 392012: Median AQI 442013: Median AQI 482014: Median AQI 462015: Median AQI 422016: Median AQI 432017: Median AQI 422018: Median AQI 362019: Median AQI 342020: Median AQI 332021: Median AQI 352022: Median AQI 392023: Median AQI 342024: Median AQI 352025: Median AQI 36199719992007200920112013201520172019202120232025
  • 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
Ozone30785%
Fine particles (PM2.5)5315%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253603184020003652124Ozone
20243603293010003549119Ozone
20232942702130003448126Ozone
2022202184180000394993Ozone
2021233214190000354984Ozone
202035735520000334480Ozone
201934934090000344580Ozone
20183553094420003654108Ozone
201736425211200004260100Ozone
20163662659830004361140Ozone
201536424312010004264112Ozone
20143642121520000466279PM2.5
201336520016410004864101PM2.5
201236522913420004466108Ozone
2011359265940000396084Ozone
201026015099110004584136Ozone
200916715980000344784Ozone
20082111683742003967169Ozone
20072071683261003974151Ozone
20062111624270004171140Ozone
1999152625616162061154216Ozone
19981971065129110048133174Ozone
199796482113131051164207Ozone

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 1997–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem