EnviroNearby

Oswego County, New York air quality history

Daily Air Quality Index summaries from EPA monitors in Oswego, New York, 2002–2025.

97%
Good days in 2025
34
Median daily AQI, 2025
0
Days above 100 in 2025
328
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Oswego, New York on 328 days. 319 of those days (97%) were in the Good range, and the median daily AQI was 34. That median is about the same as the typical monitored county in New York (median 36 across 27 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 328 days. Across the years with fuller monitoring, the share of Good days rose: an average of 77% in 2003–2005 versus 97% in 2023–2025.

Years with fewer than 120 monitored days (2002) 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%2002: Good 35 of 35 days20022003: Good 155 of 209 days2003: Moderate 43 of 209 days2003: Unhealthy for Sensitive Groups 6 of 209 days2003: Unhealthy 3 of 209 days2003: Very Unhealthy 2 of 209 days2004: Good 160 of 191 days2004: Moderate 26 of 191 days2004: Unhealthy for Sensitive Groups 5 of 191 days20042005: Good 151 of 205 days2005: Moderate 38 of 205 days2005: Unhealthy for Sensitive Groups 14 of 205 days2005: Unhealthy 2 of 205 days2006: Good 172 of 213 days2006: Moderate 36 of 213 days2006: Unhealthy for Sensitive Groups 5 of 213 days20062007: Good 170 of 214 days2007: Moderate 32 of 214 days2007: Unhealthy for Sensitive Groups 12 of 214 days2008: Good 207 of 245 days2008: Moderate 34 of 245 days2008: Unhealthy for Sensitive Groups 4 of 245 days20082009: Good 327 of 339 days2009: Moderate 11 of 339 days2009: Unhealthy for Sensitive Groups 1 of 339 days2010: Good 311 of 354 days2010: Moderate 39 of 354 days2010: Unhealthy for Sensitive Groups 4 of 354 days20102011: Good 316 of 339 days2011: Moderate 21 of 339 days2011: Unhealthy for Sensitive Groups 2 of 339 days2012: Good 314 of 347 days2012: Moderate 29 of 347 days2012: Unhealthy for Sensitive Groups 4 of 347 days20122013: Good 345 of 359 days2013: Moderate 14 of 359 days2014: Good 356 of 362 days2014: Moderate 6 of 362 days20142015: Good 277 of 286 days2015: Moderate 8 of 286 days2015: Unhealthy for Sensitive Groups 1 of 286 days2016: Good 261 of 283 days2016: Moderate 21 of 283 days2016: Unhealthy for Sensitive Groups 1 of 283 days20162017: Good 346 of 360 days2017: Moderate 14 of 360 days2018: Good 324 of 350 days2018: Moderate 25 of 350 days2018: Unhealthy for Sensitive Groups 1 of 350 days20182019: Good 316 of 321 days2019: Moderate 5 of 321 days2020: Good 349 of 359 days2020: Moderate 10 of 359 days20202021: Good 337 of 360 days2021: Moderate 23 of 360 days2022: Good 349 of 354 days2022: Moderate 5 of 354 days20222023: Good 341 of 356 days2023: Moderate 14 of 356 days2023: Unhealthy for Sensitive Groups 1 of 356 days2024: Good 353 of 359 days2024: Moderate 6 of 359 days20242025: Good 319 of 328 days2025: Moderate 9 of 328 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 year0501002002: 90th percentile AQI 342003: 90th percentile AQI 842004: 90th percentile AQI 712005: 90th percentile AQI 932006: 90th percentile AQI 672007: 90th percentile AQI 772008: 90th percentile AQI 642009: 90th percentile AQI 472010: 90th percentile AQI 542011: 90th percentile AQI 482012: 90th percentile AQI 502013: 90th percentile AQI 452014: 90th percentile AQI 422015: 90th percentile AQI 442016: 90th percentile AQI 472017: 90th percentile AQI 442018: 90th percentile AQI 472019: 90th percentile AQI 452020: 90th percentile AQI 442021: 90th percentile AQI 462022: 90th percentile AQI 432023: 90th percentile AQI 442024: 90th percentile AQI 442025: 90th percentile AQI 442002: Median AQI 282003: Median AQI 442004: Median AQI 382005: Median AQI 432006: Median AQI 382007: Median AQI 382008: Median AQI 352009: Median AQI 342010: Median AQI 342011: Median AQI 342012: Median AQI 342013: Median AQI 332014: Median AQI 312015: Median AQI 322016: Median AQI 342017: Median AQI 342018: Median AQI 322019: Median AQI 342020: Median AQI 332021: Median AQI 342022: Median AQI 322023: Median AQI 332024: Median AQI 322025: Median AQI 342002200420062008201020122014201620182020202220242025
  • 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
Ozone328100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202532831990000344480Ozone
202435935360000324461Ozone
20233563411410003344105Ozone
202235434950000324358Ozone
2021360337230000344697Ozone
2020359349100000334458Ozone
201932131650000344567Ozone
20183503242510003247112Ozone
2017360346140000344487Ozone
20162832612110003447101Ozone
2015286277810003244115Ozone
201436235660000314297Ozone
2013359345140000334584Ozone
20123473142940003450122Ozone
20113393162120003448126Ozone
20103543113940003454115Ozone
20093393271110003447108Ozone
20082452073440003564143Ozone
200721417032120003877143Ozone
20062131723650003867140Ozone
200520515138142004393166Ozone
20041911602650003871143Ozone
20032091554363204484204Ozone
2002353500000283438Ozone

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 New York with a similar median AQI in 2025

All monitored counties in New York

Source: U.S. EPA AirData, “Annual AQI by County” files for 2002–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem