EnviroNearby

Jefferson County, Ohio air quality history

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

53%
Good days in 2025
49
Median daily AQI, 2025
1
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Jefferson, Ohio on 365 days. 195 of those days (53%) were in the Good range, and the median daily AQI was 49. That median is higher than 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 fine particles (PM2.5) on 251 days. Across the years with fuller monitoring, the share of Good days fell: an average of 74% in 1980–1982 versus 56% 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%1980: Good 268 of 366 days1980: Moderate 65 of 366 days1980: Unhealthy for Sensitive Groups 17 of 366 days1980: Unhealthy 12 of 366 days1980: Very Unhealthy 4 of 366 days19801981: Good 260 of 365 days1981: Moderate 103 of 365 days1981: Unhealthy for Sensitive Groups 2 of 365 days1982: Good 282 of 365 days1982: Moderate 72 of 365 days1982: Unhealthy for Sensitive Groups 7 of 365 days1982: Unhealthy 4 of 365 days1983: Good 288 of 365 days1983: Moderate 70 of 365 days1983: Unhealthy for Sensitive Groups 7 of 365 days1984: Good 277 of 336 days1984: Moderate 53 of 336 days1984: Unhealthy for Sensitive Groups 5 of 336 days1984: Unhealthy 1 of 336 days1985: Good 249 of 365 days1985: Moderate 112 of 365 days1985: Unhealthy for Sensitive Groups 3 of 365 days1985: Very Unhealthy 1 of 365 days19851986: Good 176 of 365 days1986: Moderate 169 of 365 days1986: Unhealthy for Sensitive Groups 15 of 365 days1986: Unhealthy 4 of 365 days1986: Very Unhealthy 1 of 365 days1987: Good 178 of 365 days1987: Moderate 148 of 365 days1987: Unhealthy for Sensitive Groups 33 of 365 days1987: Unhealthy 1 of 365 days1987: Very Unhealthy 4 of 365 days1987: Hazardous 1 of 365 days1988: Good 162 of 366 days1988: Moderate 138 of 366 days1988: Unhealthy for Sensitive Groups 34 of 366 days1988: Unhealthy 24 of 366 days1988: Very Unhealthy 8 of 366 days1989: Good 175 of 365 days1989: Moderate 149 of 365 days1989: Unhealthy for Sensitive Groups 34 of 365 days1989: Unhealthy 7 of 365 days1990: Good 198 of 365 days1990: Moderate 128 of 365 days1990: Unhealthy for Sensitive Groups 26 of 365 days1990: Unhealthy 5 of 365 days1990: Very Unhealthy 8 of 365 days19901991: Good 166 of 365 days1991: Moderate 142 of 365 days1991: Unhealthy for Sensitive Groups 41 of 365 days1991: Unhealthy 15 of 365 days1991: Very Unhealthy 1 of 365 days1992: Good 223 of 366 days1992: Moderate 127 of 366 days1992: Unhealthy for Sensitive Groups 15 of 366 days1992: Unhealthy 1 of 366 days1993: Good 258 of 365 days1993: Moderate 88 of 365 days1993: Unhealthy for Sensitive Groups 18 of 365 days1993: Unhealthy 1 of 365 days1994: Good 247 of 365 days1994: Moderate 100 of 365 days1994: Unhealthy for Sensitive Groups 15 of 365 days1994: Unhealthy 2 of 365 days1994: Very Unhealthy 1 of 365 days1995: Good 230 of 365 days1995: Moderate 104 of 365 days1995: Unhealthy for Sensitive Groups 19 of 365 days1995: Unhealthy 12 of 365 days19951996: Good 274 of 366 days1996: Moderate 79 of 366 days1996: Unhealthy for Sensitive Groups 12 of 366 days1996: Unhealthy 1 of 366 days1997: Good 238 of 301 days1997: Moderate 50 of 301 days1997: Unhealthy for Sensitive Groups 12 of 301 days1997: Unhealthy 1 of 301 days1998: Good 320 of 365 days1998: Moderate 34 of 365 days1998: Unhealthy for Sensitive Groups 11 of 365 days1999: Good 110 of 365 days1999: Moderate 218 of 365 days1999: Unhealthy for Sensitive Groups 32 of 365 days1999: Unhealthy 5 of 365 days2000: Good 83 of 366 days2000: Moderate 261 of 366 days2000: Unhealthy for Sensitive Groups 18 of 366 days2000: Unhealthy 4 of 366 days20002001: Good 64 of 365 days2001: Moderate 257 of 365 days2001: Unhealthy for Sensitive Groups 39 of 365 days2001: Unhealthy 4 of 365 days2001: Very Unhealthy 1 of 365 days2002: Good 74 of 365 days2002: Moderate 245 of 365 days2002: Unhealthy for Sensitive Groups 32 of 365 days2002: Unhealthy 14 of 365 days2003: Good 88 of 365 days2003: Moderate 253 of 365 days2003: Unhealthy for Sensitive Groups 20 of 365 days2003: Unhealthy 3 of 365 days2003: Very Unhealthy 1 of 365 days2004: Good 229 of 366 days2004: Moderate 125 of 366 days2004: Unhealthy for Sensitive Groups 11 of 366 days2004: Unhealthy 1 of 366 days2005: Good 218 of 364 days2005: Moderate 119 of 364 days2005: Unhealthy for Sensitive Groups 23 of 364 days2005: Unhealthy 4 of 364 days20052006: Good 227 of 365 days2006: Moderate 118 of 365 days2006: Unhealthy for Sensitive Groups 19 of 365 days2006: Unhealthy 1 of 365 days2007: Good 216 of 365 days2007: Moderate 126 of 365 days2007: Unhealthy for Sensitive Groups 23 of 365 days2008: Good 145 of 276 days2008: Moderate 118 of 276 days2008: Unhealthy for Sensitive Groups 13 of 276 days2009: Good 159 of 263 days2009: Moderate 102 of 263 days2009: Unhealthy for Sensitive Groups 1 of 263 days2009: Unhealthy 1 of 263 days2010: Good 121 of 365 days2010: Moderate 237 of 365 days2010: Unhealthy for Sensitive Groups 6 of 365 days2010: Unhealthy 1 of 365 days20102011: Good 118 of 362 days2011: Moderate 238 of 362 days2011: Unhealthy for Sensitive Groups 6 of 362 days2012: Good 104 of 366 days2012: Moderate 246 of 366 days2012: Unhealthy for Sensitive Groups 16 of 366 days2013: Good 158 of 360 days2013: Moderate 198 of 360 days2013: Unhealthy for Sensitive Groups 4 of 360 days2014: Good 98 of 361 days2014: Moderate 258 of 361 days2014: Unhealthy for Sensitive Groups 5 of 361 days2015: Good 98 of 354 days2015: Moderate 252 of 354 days2015: Unhealthy for Sensitive Groups 4 of 354 days20152016: Good 105 of 360 days2016: Moderate 253 of 360 days2016: Unhealthy for Sensitive Groups 2 of 360 days2017: Good 96 of 359 days2017: Moderate 263 of 359 days2018: Good 96 of 344 days2018: Moderate 246 of 344 days2018: Unhealthy for Sensitive Groups 2 of 344 days2019: Good 143 of 364 days2019: Moderate 219 of 364 days2019: Unhealthy for Sensitive Groups 2 of 364 days2020: Good 263 of 359 days2020: Moderate 95 of 359 days2020: Unhealthy for Sensitive Groups 1 of 359 days20202021: Good 123 of 358 days2021: Moderate 232 of 358 days2021: Unhealthy for Sensitive Groups 2 of 358 days2021: Unhealthy 1 of 358 days2022: Good 149 of 365 days2022: Moderate 216 of 365 days2023: Good 188 of 365 days2023: Moderate 173 of 365 days2023: Unhealthy for Sensitive Groups 2 of 365 days2023: Very Unhealthy 2 of 365 days2024: Good 227 of 366 days2024: Moderate 139 of 366 days2025: Good 195 of 365 days2025: Moderate 169 of 365 days2025: Unhealthy for Sensitive Groups 1 of 365 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 year0501001501980: 90th percentile AQI 901981: 90th percentile AQI 641982: 90th percentile AQI 611983: 90th percentile AQI 641984: 90th percentile AQI 571985: 90th percentile AQI 741986: 90th percentile AQI 861987: 90th percentile AQI 1031988: 90th percentile AQI 1431989: 90th percentile AQI 1031990: 90th percentile AQI 1011991: 90th percentile AQI 1261992: 90th percentile AQI 771993: 90th percentile AQI 771994: 90th percentile AQI 871995: 90th percentile AQI 931996: 90th percentile AQI 711997: 90th percentile AQI 711998: 90th percentile AQI 581999: 90th percentile AQI 1022000: 90th percentile AQI 922001: 90th percentile AQI 1052002: 90th percentile AQI 1082003: 90th percentile AQI 932004: 90th percentile AQI 762005: 90th percentile AQI 932006: 90th percentile AQI 872007: 90th percentile AQI 902008: 90th percentile AQI 842009: 90th percentile AQI 742010: 90th percentile AQI 862011: 90th percentile AQI 802012: 90th percentile AQI 802013: 90th percentile AQI 702014: 90th percentile AQI 742015: 90th percentile AQI 762016: 90th percentile AQI 712017: 90th percentile AQI 712018: 90th percentile AQI 702019: 90th percentile AQI 662020: 90th percentile AQI 612021: 90th percentile AQI 742022: 90th percentile AQI 672023: 90th percentile AQI 702024: 90th percentile AQI 642025: 90th percentile AQI 681980: Median AQI 421981: Median AQI 431982: Median AQI 421983: Median AQI 391984: Median AQI 381985: Median AQI 411986: Median AQI 521987: Median AQI 521988: Median AQI 541989: Median AQI 511990: Median AQI 481991: Median AQI 531992: Median AQI 441993: Median AQI 401994: Median AQI 421995: Median AQI 441996: Median AQI 401997: Median AQI 381998: Median AQI 211999: Median AQI 622000: Median AQI 632001: Median AQI 662002: Median AQI 632003: Median AQI 612004: Median AQI 422005: Median AQI 462006: Median AQI 412007: Median AQI 442008: Median AQI 492009: Median AQI 452010: Median AQI 572011: Median AQI 572012: Median AQI 582013: Median AQI 532014: Median AQI 572015: Median AQI 582016: Median AQI 562017: Median AQI 562018: Median AQI 552019: Median AQI 532020: Median AQI 422021: Median AQI 552022: Median AQI 532023: Median AQI 492024: Median AQI 452025: Median AQI 491980198519901995200020052010201520202025
  • 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
Fine particles (PM2.5)25169%
Ozone11431%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
202536519516910004968101PM2.5
20243662271390000456493PM2.5
202336518817320204970229PM2.5
20223651492160000536797PM2.5
202135812323221005574157PM2.5
20203592639510004261112PM2.5
201936414321920005366123PM2.5
20183449624620005570108PM2.5
2017359962630000567199PM2.5
201636010525320005671105PM2.5
20153549825240005876117PM2.5
20143619825850005774150PM2.5
201336015819840005370147PM2.5
2012366104246160005880140PM2.5
201136211823860005780115PM2.5
201036512123761005786152PM2.5
200926315910211004574152Ozone
2008276145118130004984136Ozone
2007365216126230004490140Ozone
2006365227118191004187159Ozone
2005364218119234004693172Ozone
2004366229125111004276154Ozone
200336588253203106193202PM2.5
20023657424532140063108185PM2.5
2001365642573941066105202PM2.5
200036683261184006392177PM2.5
19993651102183250062102190PM2.5
199836532034110002158140CO
199730123850121003871172Ozone
199636627479121004071164Ozone
19953652301041912004493190Ozone
1994365247100152104287233Ozone
199336525888181004077187PM10
1992366223127151004477151PM10
199136516614241151053126222Ozone
19903651981282658048101240PM10
19893651751493470051103192PM10
198836616213834248054143238PM10
19873651781483314152103377PM10
1986365176169154105286280PM10
198536524911230104174205NO2
19843362775351003857192CO
19833652887070003964150CO
19823652827274004261187CO
198136526010320004364115CO
1980366268651712404290216NO2

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