EnviroNearby

Tuscola County, Michigan air quality history

Daily Air Quality Index summaries from EPA monitors in Tuscola, Michigan, 1990–2025.

92%
Good days in 2025
35
Median daily AQI, 2025
1
Days above 100 in 2025
358
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Tuscola, Michigan on 358 days. 329 of those days (92%) were in the Good range, and the median daily AQI was 35. That median is lower than the typical monitored county in Michigan (median 39 across 26 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 358 days. Across the years with fuller monitoring, the share of Good days rose: an average of 82% in 1990–1992 versus 91% 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%1990: Good 287 of 360 days1990: Moderate 52 of 360 days1990: Unhealthy for Sensitive Groups 17 of 360 days1990: Unhealthy 4 of 360 days19901991: Good 275 of 345 days1991: Moderate 41 of 345 days1991: Unhealthy for Sensitive Groups 22 of 345 days1991: Unhealthy 7 of 345 days1992: Good 312 of 356 days1992: Moderate 30 of 356 days1992: Unhealthy for Sensitive Groups 12 of 356 days1992: Unhealthy 2 of 356 days1993: Good 323 of 353 days1993: Moderate 24 of 353 days1993: Unhealthy for Sensitive Groups 4 of 353 days1993: Unhealthy 1 of 353 days1993: Very Unhealthy 1 of 353 days1994: Good 295 of 355 days1994: Moderate 45 of 355 days1994: Unhealthy for Sensitive Groups 13 of 355 days1994: Unhealthy 2 of 355 days1995: Good 213 of 268 days1995: Moderate 33 of 268 days1995: Unhealthy for Sensitive Groups 17 of 268 days1995: Unhealthy 5 of 268 days19951996: Good 168 of 213 days1996: Moderate 34 of 213 days1996: Unhealthy for Sensitive Groups 7 of 213 days1996: Unhealthy 4 of 213 days1997: Good 308 of 357 days1997: Moderate 35 of 357 days1997: Unhealthy for Sensitive Groups 11 of 357 days1997: Unhealthy 3 of 357 days1998: Good 286 of 361 days1998: Moderate 51 of 361 days1998: Unhealthy for Sensitive Groups 22 of 361 days1998: Unhealthy 1 of 361 days1998: Very Unhealthy 1 of 361 days1999: Good 283 of 352 days1999: Moderate 39 of 352 days1999: Unhealthy for Sensitive Groups 20 of 352 days1999: Unhealthy 9 of 352 days1999: Very Unhealthy 1 of 352 days2000: Good 313 of 349 days2000: Moderate 33 of 349 days2000: Unhealthy for Sensitive Groups 2 of 349 days2000: Unhealthy 1 of 349 days20002001: Good 313 of 365 days2001: Moderate 36 of 365 days2001: Unhealthy for Sensitive Groups 13 of 365 days2001: Unhealthy 3 of 365 days2002: Good 303 of 356 days2002: Moderate 37 of 356 days2002: Unhealthy for Sensitive Groups 13 of 356 days2002: Unhealthy 3 of 356 days2003: Good 292 of 333 days2003: Moderate 32 of 333 days2003: Unhealthy for Sensitive Groups 6 of 333 days2003: Unhealthy 3 of 333 days2004: Good 307 of 341 days2004: Moderate 30 of 341 days2004: Unhealthy for Sensitive Groups 3 of 341 days2004: Unhealthy 1 of 341 days2005: Good 301 of 361 days2005: Moderate 44 of 361 days2005: Unhealthy for Sensitive Groups 15 of 361 days2005: Unhealthy 1 of 361 days20052006: Good 321 of 362 days2006: Moderate 36 of 362 days2006: Unhealthy for Sensitive Groups 5 of 362 days2007: Good 294 of 350 days2007: Moderate 36 of 350 days2007: Unhealthy for Sensitive Groups 15 of 350 days2007: Unhealthy 5 of 350 days2008: Good 262 of 282 days2008: Moderate 19 of 282 days2008: Unhealthy for Sensitive Groups 1 of 282 days2009: Good 338 of 359 days2009: Moderate 20 of 359 days2009: Unhealthy for Sensitive Groups 1 of 359 days2010: Good 326 of 361 days2010: Moderate 35 of 361 days20102011: Good 321 of 349 days2011: Moderate 23 of 349 days2011: Unhealthy for Sensitive Groups 5 of 349 days2012: Good 288 of 348 days2012: Moderate 45 of 348 days2012: Unhealthy for Sensitive Groups 14 of 348 days2012: Unhealthy 1 of 348 days2013: Good 328 of 359 days2013: Moderate 30 of 359 days2013: Unhealthy for Sensitive Groups 1 of 359 days2014: Good 339 of 360 days2014: Moderate 21 of 360 days2015: Good 321 of 340 days2015: Moderate 19 of 340 days20152016: Good 332 of 360 days2016: Moderate 24 of 360 days2016: Unhealthy for Sensitive Groups 4 of 360 days2017: Good 326 of 346 days2017: Moderate 20 of 346 days2018: Good 324 of 356 days2018: Moderate 31 of 356 days2018: Unhealthy for Sensitive Groups 1 of 356 days2019: Good 345 of 355 days2019: Moderate 10 of 355 days2020: Good 330 of 343 days2020: Moderate 11 of 343 days2020: Unhealthy for Sensitive Groups 2 of 343 days20202021: Good 327 of 353 days2021: Moderate 25 of 353 days2021: Unhealthy for Sensitive Groups 1 of 353 days2022: Good 334 of 361 days2022: Moderate 26 of 361 days2022: Unhealthy for Sensitive Groups 1 of 361 days2023: Good 324 of 362 days2023: Moderate 32 of 362 days2023: Unhealthy for Sensitive Groups 5 of 362 days2023: Unhealthy 1 of 362 days2024: Good 331 of 364 days2024: Moderate 33 of 364 days2025: Good 329 of 358 days2025: Moderate 28 of 358 days2025: Unhealthy for Sensitive Groups 1 of 358 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 year0501001990: 90th percentile AQI 801991: 90th percentile AQI 931992: 90th percentile AQI 611993: 90th percentile AQI 491994: 90th percentile AQI 671995: 90th percentile AQI 971996: 90th percentile AQI 841997: 90th percentile AQI 671998: 90th percentile AQI 871999: 90th percentile AQI 842000: 90th percentile AQI 542001: 90th percentile AQI 712002: 90th percentile AQI 642003: 90th percentile AQI 612004: 90th percentile AQI 502005: 90th percentile AQI 742006: 90th percentile AQI 542007: 90th percentile AQI 742008: 90th percentile AQI 492009: 90th percentile AQI 462010: 90th percentile AQI 502011: 90th percentile AQI 492012: 90th percentile AQI 742013: 90th percentile AQI 502014: 90th percentile AQI 462015: 90th percentile AQI 482016: 90th percentile AQI 492017: 90th percentile AQI 472018: 90th percentile AQI 502019: 90th percentile AQI 462020: 90th percentile AQI 442021: 90th percentile AQI 482022: 90th percentile AQI 492023: 90th percentile AQI 512024: 90th percentile AQI 492025: 90th percentile AQI 491990: Median AQI 371991: Median AQI 361992: Median AQI 331993: Median AQI 331994: Median AQI 351995: Median AQI 371996: Median AQI 311997: Median AQI 351998: Median AQI 351999: Median AQI 362000: Median AQI 332001: Median AQI 332002: Median AQI 322003: Median AQI 332004: Median AQI 332005: Median AQI 352006: Median AQI 342007: Median AQI 362008: Median AQI 352009: Median AQI 332010: Median AQI 362011: Median AQI 362012: Median AQI 342013: Median AQI 342014: Median AQI 342015: Median AQI 342016: Median AQI 342017: Median AQI 332018: Median AQI 352019: Median AQI 332020: Median AQI 322021: Median AQI 342022: Median AQI 342023: Median AQI 342024: Median AQI 342025: Median AQI 3519901995200020052010201520202025
  • 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
Ozone358100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253583292810003549112Ozone
2024364331330000344984Ozone
20233623243251003451154Ozone
20223613342610003449105Ozone
20213533272510003448101Ozone
20203433301120003244101Ozone
2019355345100000334677Ozone
20183563243110003550105Ozone
2017346326200000334787Ozone
20163603322440003449115Ozone
20153403211900003448100Ozone
2014360339210000344687Ozone
20133593283010003450112Ozone
201234828845141003474159Ozone
20113493212350003649136Ozone
20103613263500003650100Ozone
20093593382010003346101Ozone
20082822621910003549115Ozone
200735029436155003674172Ozone
20063623213650003454147Ozone
200536130144151003574156Ozone
20043413073031003350154Ozone
20033332923263003361169Ozone
200235630337133003264179Ozone
200136531336133003371177Ozone
20003493133321003354161Ozone
199935228339209103684214Ozone
199836128651221103587203Ozone
199735730835113003567169Ozone
19962131683474003184192Ozone
199526821333175003797169Ozone
199435529545132003567174Ozone
19933533232441103349201Ozone
199235631230122003361169Ozone
199134527541227003693179Ozone
199036028752174003780164Ozone

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 Michigan with a similar median AQI in 2025

All monitored counties in Michigan

Source: U.S. EPA AirData, “Annual AQI by County” files for 1990–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem