EnviroNearby

Portage County, Ohio air quality history

Daily Air Quality Index summaries from EPA monitors in Portage, Ohio, 1980–2025.

78%
Good days in 2025
43
Median daily AQI, 2025
2
Days above 100 in 2025
245
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Portage, Ohio on 245 days. 190 of those days (78%) were in the Good range, and the median daily AQI was 43. That median is about the same as the typical monitored county in Ohio (median 43 across 36 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 245 days. Across the years with fuller monitoring, the share of Good days rose: an average of 71% in 1980–1982 versus 76% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (245 of 365 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

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 253 of 339 days1980: Moderate 53 of 339 days1980: Unhealthy for Sensitive Groups 25 of 339 days1980: Unhealthy 8 of 339 days19801981: Good 218 of 307 days1981: Moderate 46 of 307 days1981: Unhealthy for Sensitive Groups 19 of 307 days1981: Unhealthy 18 of 307 days1981: Very Unhealthy 6 of 307 days1982: Good 230 of 335 days1982: Moderate 53 of 335 days1982: Unhealthy for Sensitive Groups 30 of 335 days1982: Unhealthy 18 of 335 days1982: Very Unhealthy 4 of 335 days1983: Good 256 of 347 days1983: Moderate 40 of 347 days1983: Unhealthy for Sensitive Groups 26 of 347 days1983: Unhealthy 20 of 347 days1983: Very Unhealthy 5 of 347 days1984: Good 276 of 365 days1984: Moderate 54 of 365 days1984: Unhealthy for Sensitive Groups 27 of 365 days1984: Unhealthy 8 of 365 days1985: Good 270 of 361 days1985: Moderate 54 of 361 days1985: Unhealthy for Sensitive Groups 26 of 361 days1985: Unhealthy 11 of 361 days19851986: Good 196 of 295 days1986: Moderate 61 of 295 days1986: Unhealthy for Sensitive Groups 33 of 295 days1986: Unhealthy 5 of 295 days1987: Good 115 of 208 days1987: Moderate 49 of 208 days1987: Unhealthy for Sensitive Groups 29 of 208 days1987: Unhealthy 13 of 208 days1987: Very Unhealthy 2 of 208 days1988: Good 107 of 211 days1988: Moderate 37 of 211 days1988: Unhealthy for Sensitive Groups 25 of 211 days1988: Unhealthy 23 of 211 days1988: Very Unhealthy 19 of 211 days1989: Good 131 of 213 days1989: Moderate 53 of 213 days1989: Unhealthy for Sensitive Groups 21 of 213 days1989: Unhealthy 8 of 213 days1990: Good 137 of 212 days1990: Moderate 42 of 212 days1990: Unhealthy for Sensitive Groups 26 of 212 days1990: Unhealthy 7 of 212 days19901991: Good 99 of 202 days1991: Moderate 44 of 202 days1991: Unhealthy for Sensitive Groups 37 of 202 days1991: Unhealthy 22 of 202 days1992: Good 155 of 206 days1992: Moderate 34 of 206 days1992: Unhealthy for Sensitive Groups 11 of 206 days1992: Unhealthy 6 of 206 days1993: Good 135 of 208 days1993: Moderate 51 of 208 days1993: Unhealthy for Sensitive Groups 16 of 208 days1993: Unhealthy 6 of 208 days1994: Good 136 of 210 days1994: Moderate 45 of 210 days1994: Unhealthy for Sensitive Groups 25 of 210 days1994: Unhealthy 4 of 210 days1995: Good 126 of 210 days1995: Moderate 59 of 210 days1995: Unhealthy for Sensitive Groups 18 of 210 days1995: Unhealthy 6 of 210 days1995: Very Unhealthy 1 of 210 days19951996: Good 134 of 211 days1996: Moderate 40 of 211 days1996: Unhealthy for Sensitive Groups 30 of 211 days1996: Unhealthy 7 of 211 days1997: Good 136 of 212 days1997: Moderate 57 of 212 days1997: Unhealthy for Sensitive Groups 16 of 212 days1997: Unhealthy 3 of 212 days1998: Good 121 of 212 days1998: Moderate 46 of 212 days1998: Unhealthy for Sensitive Groups 36 of 212 days1998: Unhealthy 8 of 212 days1998: Very Unhealthy 1 of 212 days1999: Good 95 of 245 days1999: Moderate 106 of 245 days1999: Unhealthy for Sensitive Groups 29 of 245 days1999: Unhealthy 14 of 245 days1999: Very Unhealthy 1 of 245 days2000: Good 119 of 255 days2000: Moderate 115 of 255 days2000: Unhealthy for Sensitive Groups 18 of 255 days2000: Unhealthy 3 of 255 days20002001: Good 122 of 263 days2001: Moderate 108 of 263 days2001: Unhealthy for Sensitive Groups 23 of 263 days2001: Unhealthy 10 of 263 days2002: Good 122 of 250 days2002: Moderate 97 of 250 days2002: Unhealthy for Sensitive Groups 14 of 250 days2002: Unhealthy 17 of 250 days2003: Good 116 of 259 days2003: Moderate 122 of 259 days2003: Unhealthy for Sensitive Groups 17 of 259 days2003: Unhealthy 2 of 259 days2003: Very Unhealthy 2 of 259 days2004: Good 142 of 260 days2004: Moderate 101 of 260 days2004: Unhealthy for Sensitive Groups 16 of 260 days2004: Unhealthy 1 of 260 days2005: Good 103 of 257 days2005: Moderate 117 of 257 days2005: Unhealthy for Sensitive Groups 28 of 257 days2005: Unhealthy 8 of 257 days2005: Very Unhealthy 1 of 257 days20052006: Good 159 of 263 days2006: Moderate 101 of 263 days2006: Unhealthy for Sensitive Groups 3 of 263 days2007: Good 147 of 256 days2007: Moderate 95 of 256 days2007: Unhealthy for Sensitive Groups 13 of 256 days2007: Unhealthy 1 of 256 days2008: Good 171 of 258 days2008: Moderate 85 of 258 days2008: Unhealthy for Sensitive Groups 2 of 258 days2009: Good 181 of 259 days2009: Moderate 78 of 259 days2010: Good 176 of 260 days2010: Moderate 80 of 260 days2010: Unhealthy for Sensitive Groups 4 of 260 days20102011: Good 174 of 259 days2011: Moderate 82 of 259 days2011: Unhealthy for Sensitive Groups 3 of 259 days2012: Good 158 of 259 days2012: Moderate 94 of 259 days2012: Unhealthy for Sensitive Groups 6 of 259 days2012: Unhealthy 1 of 259 days2013: Good 198 of 237 days2013: Moderate 39 of 237 days2014: Good 192 of 242 days2014: Moderate 50 of 242 days2015: Good 211 of 260 days2015: Moderate 49 of 260 days20152016: Good 209 of 247 days2016: Moderate 38 of 247 days2017: Good 226 of 281 days2017: Moderate 55 of 281 days2018: Good 214 of 279 days2018: Moderate 65 of 279 days2019: Good 233 of 270 days2019: Moderate 37 of 270 days2020: Good 226 of 262 days2020: Moderate 35 of 262 days2020: Unhealthy for Sensitive Groups 1 of 262 days20202021: Good 205 of 263 days2021: Moderate 57 of 263 days2021: Unhealthy for Sensitive Groups 1 of 263 days2022: Good 226 of 282 days2022: Moderate 52 of 282 days2022: Unhealthy for Sensitive Groups 3 of 282 days2022: Unhealthy 1 of 282 days2023: Good 178 of 241 days2023: Moderate 60 of 241 days2023: Unhealthy for Sensitive Groups 2 of 241 days2023: Unhealthy 1 of 241 days2024: Good 187 of 245 days2024: Moderate 56 of 245 days2024: Unhealthy for Sensitive Groups 2 of 245 days2025: Good 190 of 245 days2025: Moderate 53 of 245 days2025: Unhealthy for Sensitive Groups 2 of 245 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 year0501001502001980: 90th percentile AQI 1001981: 90th percentile AQI 1291982: 90th percentile AQI 1221983: 90th percentile AQI 1221984: 90th percentile AQI 1001985: 90th percentile AQI 1011986: 90th percentile AQI 1121987: 90th percentile AQI 1431988: 90th percentile AQI 1821989: 90th percentile AQI 1151990: 90th percentile AQI 1221991: 90th percentile AQI 1541992: 90th percentile AQI 841993: 90th percentile AQI 1051994: 90th percentile AQI 1151995: 90th percentile AQI 1051996: 90th percentile AQI 1191997: 90th percentile AQI 931998: 90th percentile AQI 1291999: 90th percentile AQI 1332000: 90th percentile AQI 902001: 90th percentile AQI 1082002: 90th percentile AQI 1222003: 90th percentile AQI 972004: 90th percentile AQI 932005: 90th percentile AQI 1192006: 90th percentile AQI 742007: 90th percentile AQI 832008: 90th percentile AQI 672009: 90th percentile AQI 652010: 90th percentile AQI 672011: 90th percentile AQI 682012: 90th percentile AQI 772013: 90th percentile AQI 562014: 90th percentile AQI 582015: 90th percentile AQI 602016: 90th percentile AQI 542017: 90th percentile AQI 562018: 90th percentile AQI 632019: 90th percentile AQI 542020: 90th percentile AQI 582021: 90th percentile AQI 602022: 90th percentile AQI 612023: 90th percentile AQI 712024: 90th percentile AQI 672025: 90th percentile AQI 711980: Median AQI 321981: Median AQI 381982: Median AQI 381983: Median AQI 341984: Median AQI 341985: Median AQI 381986: Median AQI 421987: Median AQI 481988: Median AQI 501989: Median AQI 451990: Median AQI 441991: Median AQI 541992: Median AQI 391993: Median AQI 441994: Median AQI 451995: Median AQI 451996: Median AQI 451997: Median AQI 441998: Median AQI 471999: Median AQI 582000: Median AQI 532001: Median AQI 522002: Median AQI 522003: Median AQI 522004: Median AQI 482005: Median AQI 562006: Median AQI 452007: Median AQI 442008: Median AQI 432009: Median AQI 402010: Median AQI 432011: Median AQI 402012: Median AQI 442013: Median AQI 322014: Median AQI 372015: Median AQI 382016: Median AQI 382017: Median AQI 402018: Median AQI 392019: Median AQI 382020: Median AQI 402021: Median AQI 402022: Median AQI 412023: Median AQI 432024: Median AQI 432025: Median AQI 431980198519901995200020052010201520202025
  • 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
Ozone245100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20252451905320004371150Ozone
20242451875620004367108Ozone
20232411786021004371159Ozone
20222822265231004161159Ozone
20212632055710004060108Ozone
20202622263510004058101Ozone
2019270233370000385487Ozone
20182792146500003963100Ozone
2017281226550000405697Ozone
2016247209380000385490Ozone
2015260211490000386093Ozone
2014242192500000375887Ozone
2013237198390000325690Ozone
20122591589461004477164Ozone
20112591748230004068122Ozone
20102601768040004367126Ozone
2009259181780000406597Ozone
20082581718520004367115Ozone
200725614795131004483161Ozone
200626315910130004574133Ozone
20052571031172881056119202Ozone
2004260142101161004893151Ozone
2003259116122172205297219Ozone
20022501229714170052122187Ozone
200126312210823100052108195Ozone
2000255119115183005390182Ozone
19992459510629141058133208Ozone
1998212121463681047129212Ozone
199721213657163004493164Ozone
1996211134403070045119174Ozone
1995210126591861045105202Ozone
1994210136452540045115161Ozone
1993208135511660044105182Ozone
199220615534116003984192Ozone
1991202994437220054154195Ozone
1990212137422670044122185Ozone
1989213131532180045115200Ozone
198821110737252319050182249Ozone
19872081154929132048143215Ozone
1986295196613350042112192Ozone
19853612705426110038101200Ozone
1984365276542780034100187Ozone
19833472564026205034122209Ozone
19823352305330184038122273Ozone
19813072184619186038129254Ozone
1980339253532580032100182Ozone

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 Ohio with a similar median AQI in 2025

All monitored counties in Ohio

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