EnviroNearby

Rock County, Wisconsin air quality history

Daily Air Quality Index summaries from EPA monitors in Rock, Wisconsin, 1980–2025.

80%
Good days in 2025
42
Median daily AQI, 2025
1
Days above 100 in 2025
199
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Rock, Wisconsin on 199 days. 159 of those days (80%) were in the Good range, and the median daily AQI was 42. That median is higher than the typical monitored county in Wisconsin (median 38 across 29 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 199 days. Across the years with fuller monitoring, the share of Good days fell: an average of 81% in 1980–1982 versus 76% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (199 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 306 of 366 days1980: Moderate 41 of 366 days1980: Unhealthy for Sensitive Groups 18 of 366 days1980: Unhealthy 1 of 366 days19801981: Good 284 of 365 days1981: Moderate 49 of 365 days1981: Unhealthy for Sensitive Groups 24 of 365 days1981: Unhealthy 7 of 365 days1981: Very Unhealthy 1 of 365 days1982: Good 301 of 365 days1982: Moderate 48 of 365 days1982: Unhealthy for Sensitive Groups 14 of 365 days1982: Unhealthy 2 of 365 days1983: Good 277 of 364 days1983: Moderate 53 of 364 days1983: Unhealthy for Sensitive Groups 22 of 364 days1983: Unhealthy 11 of 364 days1983: Very Unhealthy 1 of 364 days1984: Good 283 of 349 days1984: Moderate 54 of 349 days1984: Unhealthy for Sensitive Groups 10 of 349 days1984: Unhealthy 2 of 349 days1985: Good 297 of 364 days1985: Moderate 50 of 364 days1985: Unhealthy for Sensitive Groups 15 of 364 days1985: Unhealthy 2 of 364 days19851986: Good 312 of 365 days1986: Moderate 42 of 365 days1986: Unhealthy for Sensitive Groups 9 of 365 days1986: Unhealthy 2 of 365 days1987: Good 289 of 365 days1987: Moderate 51 of 365 days1987: Unhealthy for Sensitive Groups 21 of 365 days1987: Unhealthy 4 of 365 days1988: Good 186 of 289 days1988: Moderate 58 of 289 days1988: Unhealthy for Sensitive Groups 30 of 289 days1988: Unhealthy 13 of 289 days1988: Very Unhealthy 2 of 289 days1989: Good 105 of 184 days1989: Moderate 45 of 184 days1989: Unhealthy for Sensitive Groups 24 of 184 days1989: Unhealthy 9 of 184 days1989: Very Unhealthy 1 of 184 days1990: Good 115 of 184 days1990: Moderate 60 of 184 days1990: Unhealthy for Sensitive Groups 8 of 184 days1990: Unhealthy 1 of 184 days19901991: Good 111 of 184 days1991: Moderate 49 of 184 days1991: Unhealthy for Sensitive Groups 16 of 184 days1991: Unhealthy 8 of 184 days1992: Good 151 of 184 days1992: Moderate 19 of 184 days1992: Unhealthy for Sensitive Groups 12 of 184 days1992: Unhealthy 2 of 184 days1993: Good 159 of 184 days1993: Moderate 22 of 184 days1993: Unhealthy for Sensitive Groups 3 of 184 days1994: Good 144 of 184 days1994: Moderate 32 of 184 days1994: Unhealthy for Sensitive Groups 6 of 184 days1994: Unhealthy 2 of 184 days1995: Good 133 of 184 days1995: Moderate 36 of 184 days1995: Unhealthy for Sensitive Groups 11 of 184 days1995: Unhealthy 4 of 184 days19951996: Good 140 of 184 days1996: Moderate 30 of 184 days1996: Unhealthy for Sensitive Groups 10 of 184 days1996: Unhealthy 4 of 184 days1997: Good 118 of 184 days1997: Moderate 45 of 184 days1997: Unhealthy for Sensitive Groups 18 of 184 days1997: Unhealthy 3 of 184 days1998: Good 101 of 184 days1998: Moderate 58 of 184 days1998: Unhealthy for Sensitive Groups 22 of 184 days1998: Unhealthy 3 of 184 days1999: Good 112 of 243 days1999: Moderate 108 of 243 days1999: Unhealthy for Sensitive Groups 14 of 243 days1999: Unhealthy 9 of 243 days2000: Good 114 of 243 days2000: Moderate 113 of 243 days2000: Unhealthy for Sensitive Groups 13 of 243 days2000: Unhealthy 3 of 243 days20002001: Good 124 of 243 days2001: Moderate 103 of 243 days2001: Unhealthy for Sensitive Groups 14 of 243 days2001: Unhealthy 2 of 243 days2002: Good 137 of 246 days2002: Moderate 90 of 246 days2002: Unhealthy for Sensitive Groups 15 of 246 days2002: Unhealthy 4 of 246 days2003: Good 126 of 204 days2003: Moderate 63 of 204 days2003: Unhealthy for Sensitive Groups 15 of 204 days2004: Good 164 of 198 days2004: Moderate 31 of 198 days2004: Unhealthy for Sensitive Groups 3 of 198 days2005: Good 119 of 185 days2005: Moderate 52 of 185 days2005: Unhealthy for Sensitive Groups 14 of 185 days20052006: Good 147 of 185 days2006: Moderate 37 of 185 days2006: Unhealthy for Sensitive Groups 1 of 185 days2007: Good 138 of 188 days2007: Moderate 38 of 188 days2007: Unhealthy for Sensitive Groups 12 of 188 days2008: Good 156 of 194 days2008: Moderate 38 of 194 days2009: Good 163 of 192 days2009: Moderate 29 of 192 days2010: Good 183 of 214 days2010: Moderate 30 of 214 days2010: Unhealthy for Sensitive Groups 1 of 214 days20102011: Good 152 of 192 days2011: Moderate 37 of 192 days2011: Unhealthy for Sensitive Groups 3 of 192 days2012: Good 123 of 191 days2012: Moderate 57 of 191 days2012: Unhealthy for Sensitive Groups 11 of 191 days2013: Good 146 of 190 days2013: Moderate 43 of 190 days2013: Unhealthy for Sensitive Groups 1 of 190 days2014: Good 162 of 195 days2014: Moderate 28 of 195 days2014: Unhealthy for Sensitive Groups 5 of 195 days2015: Good 165 of 192 days2015: Moderate 27 of 192 days20152016: Good 159 of 187 days2016: Moderate 23 of 187 days2016: Unhealthy for Sensitive Groups 5 of 187 days2017: Good 203 of 234 days2017: Moderate 31 of 234 days2018: Good 217 of 246 days2018: Moderate 28 of 246 days2018: Unhealthy for Sensitive Groups 1 of 246 days2019: Good 185 of 203 days2019: Moderate 18 of 203 days2020: Good 192 of 210 days2020: Moderate 15 of 210 days2020: Unhealthy for Sensitive Groups 3 of 210 days20202021: Good 173 of 205 days2021: Moderate 32 of 205 days2022: Good 184 of 202 days2022: Moderate 18 of 202 days2023: Good 131 of 205 days2023: Moderate 52 of 205 days2023: Unhealthy for Sensitive Groups 20 of 205 days2023: Unhealthy 2 of 205 days2024: Good 171 of 205 days2024: Moderate 32 of 205 days2024: Unhealthy for Sensitive Groups 2 of 205 days2025: Good 159 of 199 days2025: Moderate 39 of 199 days2025: Unhealthy for Sensitive Groups 1 of 199 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 741981: 90th percentile AQI 1001982: 90th percentile AQI 671983: 90th percentile AQI 1001984: 90th percentile AQI 771985: 90th percentile AQI 741986: 90th percentile AQI 621987: 90th percentile AQI 841988: 90th percentile AQI 1221989: 90th percentile AQI 1151990: 90th percentile AQI 931991: 90th percentile AQI 1151992: 90th percentile AQI 841993: 90th percentile AQI 581994: 90th percentile AQI 741995: 90th percentile AQI 931996: 90th percentile AQI 871997: 90th percentile AQI 1081998: 90th percentile AQI 1151999: 90th percentile AQI 992000: 90th percentile AQI 842001: 90th percentile AQI 902002: 90th percentile AQI 972003: 90th percentile AQI 932004: 90th percentile AQI 712005: 90th percentile AQI 972006: 90th percentile AQI 642007: 90th percentile AQI 902008: 90th percentile AQI 642009: 90th percentile AQI 542010: 90th percentile AQI 612011: 90th percentile AQI 742012: 90th percentile AQI 932013: 90th percentile AQI 672014: 90th percentile AQI 612015: 90th percentile AQI 582016: 90th percentile AQI 612017: 90th percentile AQI 582018: 90th percentile AQI 542019: 90th percentile AQI 502020: 90th percentile AQI 492021: 90th percentile AQI 612022: 90th percentile AQI 502023: 90th percentile AQI 1082024: 90th percentile AQI 582025: 90th percentile AQI 611980: Median AQI 311981: Median AQI 351982: Median AQI 311983: Median AQI 361984: Median AQI 371985: Median AQI 341986: Median AQI 321987: Median AQI 311988: Median AQI 431989: Median AQI 481990: Median AQI 461991: Median AQI 451992: Median AQI 361993: Median AQI 371994: Median AQI 411995: Median AQI 421996: Median AQI 411997: Median AQI 451998: Median AQI 491999: Median AQI 532000: Median AQI 512001: Median AQI 502002: Median AQI 482003: Median AQI 472004: Median AQI 402005: Median AQI 442006: Median AQI 422007: Median AQI 432008: Median AQI 422009: Median AQI 372010: Median AQI 412011: Median AQI 412012: Median AQI 452013: Median AQI 422014: Median AQI 402015: Median AQI 412016: Median AQI 392017: Median AQI 402018: Median AQI 392019: Median AQI 382020: Median AQI 382021: Median AQI 412022: Median AQI 392023: Median AQI 462024: Median AQI 412025: Median AQI 421980198519901995200020052010201520202025
  • 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
Ozone199100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20251991593910004261108Ozone
20242051713220004158112Ozone
2023205131522020046108177Ozone
2022202184180000395097Ozone
20212051733200004161100Ozone
20202101921530003849105Ozone
2019203185180000385077Ozone
20182462172810003954133Ozone
2017234203310000405887Ozone
20161871592350003961119Ozone
20151921652700004158100Ozone
20141951622850004061119Ozone
20131901464310004267105Ozone
201219112357110004593143Ozone
20111921523730004174108Ozone
20102141833010004161101Ozone
2009192163290000375493Ozone
2008194156380000426493Ozone
200718813838120004390140Ozone
20061851473710004264112Ozone
200518511952140004497150Ozone
20041981643130004071136Ozone
200320412663150004793140Ozone
200224613790154004897174Ozone
2001243124103142005090161Ozone
2000243114113133005184172Ozone
1999243112108149005399179Ozone
1998184101582230049115164Ozone
1997184118451830045108161Ozone
199618414030104004187179Ozone
199518413336114004293182Ozone
19941841443262004174179Ozone
19931841592230003758150Ozone
199218415119122003684159Ozone
1991184111491680045115190Ozone
19901841156081004693156Ozone
1989184105452491048115205Ozone
19882891865830132043122207Ozone
198736528951214003184174Ozone
19863653124292003262159NO2
198536429750152003474177NO2
198434928354102003777166NO2
19833642775322111036100204NO2
198236530148142003167174NO2
1981365284492471035100201Ozone
198036630641181003174156Ozone

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 Wisconsin with a similar median AQI in 2025

All monitored counties in Wisconsin

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