EnviroNearby

Boone County, Kentucky air quality history

Daily Air Quality Index summaries from EPA monitors in Boone, Kentucky, 1980–2025.

88%
Good days in 2025
38
Median daily AQI, 2025
3
Days above 100 in 2025
242
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Boone, Kentucky on 242 days. 212 of those days (88%) were in the Good range, and the median daily AQI was 38. That median is about the same as the typical monitored county in Kentucky (median 39 across 25 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 242 days. Across the years with fuller monitoring, the share of Good days rose: an average of 73% in 1980–1982 versus 81% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (242 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 264 of 364 days1980: Moderate 57 of 364 days1980: Unhealthy for Sensitive Groups 28 of 364 days1980: Unhealthy 12 of 364 days1980: Very Unhealthy 3 of 364 days19801981: Good 277 of 365 days1981: Moderate 55 of 365 days1981: Unhealthy for Sensitive Groups 29 of 365 days1981: Unhealthy 4 of 365 days1982: Good 248 of 358 days1982: Moderate 74 of 358 days1982: Unhealthy for Sensitive Groups 22 of 358 days1982: Unhealthy 13 of 358 days1982: Very Unhealthy 1 of 358 days1983: Good 254 of 345 days1983: Moderate 49 of 345 days1983: Unhealthy for Sensitive Groups 34 of 345 days1983: Unhealthy 8 of 345 days1984: Good 271 of 362 days1984: Moderate 60 of 362 days1984: Unhealthy for Sensitive Groups 25 of 362 days1984: Unhealthy 6 of 362 days1985: Good 266 of 350 days1985: Moderate 56 of 350 days1985: Unhealthy for Sensitive Groups 26 of 350 days1985: Unhealthy 2 of 350 days19851986: Good 263 of 363 days1986: Moderate 63 of 363 days1986: Unhealthy for Sensitive Groups 31 of 363 days1986: Unhealthy 5 of 363 days1986: Very Unhealthy 1 of 363 days1987: Good 162 of 257 days1987: Moderate 53 of 257 days1987: Unhealthy for Sensitive Groups 32 of 257 days1987: Unhealthy 10 of 257 days1988: Good 106 of 199 days1988: Moderate 42 of 199 days1988: Unhealthy for Sensitive Groups 24 of 199 days1988: Unhealthy 24 of 199 days1988: Very Unhealthy 3 of 199 days1989: Good 140 of 213 days1989: Moderate 48 of 213 days1989: Unhealthy for Sensitive Groups 23 of 213 days1989: Unhealthy 2 of 213 days1990: Good 133 of 212 days1990: Moderate 45 of 212 days1990: Unhealthy for Sensitive Groups 28 of 212 days1990: Unhealthy 6 of 212 days19901991: Good 137 of 213 days1991: Moderate 46 of 213 days1991: Unhealthy for Sensitive Groups 24 of 213 days1991: Unhealthy 6 of 213 days1992: Good 160 of 204 days1992: Moderate 40 of 204 days1992: Unhealthy for Sensitive Groups 4 of 204 days1993: Good 138 of 212 days1993: Moderate 59 of 212 days1993: Unhealthy for Sensitive Groups 15 of 212 days1994: Good 126 of 212 days1994: Moderate 55 of 212 days1994: Unhealthy for Sensitive Groups 26 of 212 days1994: Unhealthy 5 of 212 days1995: Good 146 of 214 days1995: Moderate 47 of 214 days1995: Unhealthy for Sensitive Groups 20 of 214 days1995: Unhealthy 1 of 214 days19951996: Good 157 of 214 days1996: Moderate 48 of 214 days1996: Unhealthy for Sensitive Groups 7 of 214 days1996: Unhealthy 2 of 214 days1997: Good 156 of 214 days1997: Moderate 45 of 214 days1997: Unhealthy for Sensitive Groups 13 of 214 days1998: Good 129 of 209 days1998: Moderate 55 of 209 days1998: Unhealthy for Sensitive Groups 22 of 209 days1998: Unhealthy 3 of 209 days1999: Good 123 of 214 days1999: Moderate 58 of 214 days1999: Unhealthy for Sensitive Groups 27 of 214 days1999: Unhealthy 6 of 214 days2000: Good 190 of 245 days2000: Moderate 44 of 245 days2000: Unhealthy for Sensitive Groups 8 of 245 days2000: Unhealthy 3 of 245 days20002001: Good 176 of 244 days2001: Moderate 56 of 244 days2001: Unhealthy for Sensitive Groups 12 of 244 days2002: Good 166 of 245 days2002: Moderate 47 of 245 days2002: Unhealthy for Sensitive Groups 20 of 245 days2002: Unhealthy 12 of 245 days2003: Good 181 of 237 days2003: Moderate 45 of 237 days2003: Unhealthy for Sensitive Groups 10 of 237 days2003: Unhealthy 1 of 237 days2004: Good 208 of 245 days2004: Moderate 35 of 245 days2004: Unhealthy for Sensitive Groups 2 of 245 days2005: Good 147 of 234 days2005: Moderate 62 of 234 days2005: Unhealthy for Sensitive Groups 25 of 234 days20052006: Good 193 of 244 days2006: Moderate 47 of 244 days2006: Unhealthy for Sensitive Groups 4 of 244 days2007: Good 154 of 245 days2007: Moderate 73 of 245 days2007: Unhealthy for Sensitive Groups 18 of 245 days2008: Good 206 of 241 days2008: Moderate 35 of 241 days2009: Good 217 of 241 days2009: Moderate 24 of 241 days2010: Good 193 of 245 days2010: Moderate 50 of 245 days2010: Unhealthy for Sensitive Groups 2 of 245 days20102011: Good 200 of 239 days2011: Moderate 36 of 239 days2011: Unhealthy for Sensitive Groups 3 of 239 days2012: Good 179 of 245 days2012: Moderate 59 of 245 days2012: Unhealthy for Sensitive Groups 7 of 245 days2013: Good 227 of 244 days2013: Moderate 16 of 244 days2013: Unhealthy for Sensitive Groups 1 of 244 days2014: Good 231 of 245 days2014: Moderate 14 of 245 days2015: Good 221 of 244 days2015: Moderate 22 of 244 days2015: Unhealthy for Sensitive Groups 1 of 244 days20152016: Good 212 of 241 days2016: Moderate 29 of 241 days2017: Good 208 of 223 days2017: Moderate 15 of 223 days2018: Good 218 of 243 days2018: Moderate 23 of 243 days2018: Unhealthy for Sensitive Groups 1 of 243 days2018: Unhealthy 1 of 243 days2019: Good 222 of 239 days2019: Moderate 17 of 239 days2020: Good 218 of 242 days2020: Moderate 24 of 242 days20202021: Good 225 of 244 days2021: Moderate 19 of 244 days2022: Good 173 of 199 days2022: Moderate 26 of 199 days2023: Good 187 of 245 days2023: Moderate 51 of 245 days2023: Unhealthy for Sensitive Groups 6 of 245 days2023: Unhealthy 1 of 245 days2024: Good 183 of 230 days2024: Moderate 46 of 230 days2024: Unhealthy for Sensitive Groups 1 of 230 days2025: Good 212 of 242 days2025: Moderate 27 of 242 days2025: Unhealthy for Sensitive Groups 3 of 242 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 1081981: 90th percentile AQI 971982: 90th percentile AQI 1011983: 90th percentile AQI 1121984: 90th percentile AQI 931985: 90th percentile AQI 901986: 90th percentile AQI 1011987: 90th percentile AQI 1191988: 90th percentile AQI 1591989: 90th percentile AQI 1081990: 90th percentile AQI 1191991: 90th percentile AQI 1121992: 90th percentile AQI 741993: 90th percentile AQI 931994: 90th percentile AQI 1121995: 90th percentile AQI 1001996: 90th percentile AQI 871997: 90th percentile AQI 931998: 90th percentile AQI 1051999: 90th percentile AQI 1192000: 90th percentile AQI 772001: 90th percentile AQI 842002: 90th percentile AQI 1082003: 90th percentile AQI 802004: 90th percentile AQI 642005: 90th percentile AQI 1052006: 90th percentile AQI 642007: 90th percentile AQI 932008: 90th percentile AQI 582009: 90th percentile AQI 502010: 90th percentile AQI 642011: 90th percentile AQI 672012: 90th percentile AQI 842013: 90th percentile AQI 492014: 90th percentile AQI 482015: 90th percentile AQI 502016: 90th percentile AQI 512017: 90th percentile AQI 472018: 90th percentile AQI 512019: 90th percentile AQI 492020: 90th percentile AQI 502021: 90th percentile AQI 492022: 90th percentile AQI 542023: 90th percentile AQI 672024: 90th percentile AQI 642025: 90th percentile AQI 541980: Median AQI 351981: Median AQI 381982: Median AQI 401983: Median AQI 351984: Median AQI 371985: Median AQI 351986: Median AQI 341987: Median AQI 441988: Median AQI 491989: Median AQI 441990: Median AQI 441991: Median AQI 451992: Median AQI 401993: Median AQI 441994: Median AQI 461995: Median AQI 441996: Median AQI 401997: Median AQI 401998: Median AQI 451999: Median AQI 482000: Median AQI 412001: Median AQI 432002: Median AQI 432003: Median AQI 402004: Median AQI 402005: Median AQI 432006: Median AQI 412007: Median AQI 472008: Median AQI 402009: Median AQI 362010: Median AQI 422011: Median AQI 412012: Median AQI 432013: Median AQI 382014: Median AQI 372015: Median AQI 392016: Median AQI 382017: Median AQI 382018: Median AQI 382019: Median AQI 392020: Median AQI 362021: Median AQI 392022: Median AQI 412023: Median AQI 442024: Median AQI 432025: Median AQI 381980198519901995200020052010201520202025
  • 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
Ozone242100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20252422122730003854108Ozone
20242301834610004364129Ozone
20232451875161004467156Ozone
2022199173260000415497Ozone
2021244225190000394990Ozone
2020242218240000365087Ozone
2019239222170000394980Ozone
20182432182311003851151Ozone
2017223208150000384797Ozone
2016241212290000385187Ozone
20152442212210003950101Ozone
2014245231140000374880Ozone
20132442271610003849101Ozone
20122451795970004384150Ozone
20112392003630004167115Ozone
20102451935020004264136Ozone
2009241217240000365097Ozone
2008241206350000405884Ozone
200724515473180004793136Ozone
20062441934740004164105Ozone
2005234147622500043105140Ozone
20042452083520004064122Ozone
200323718145101004080159Ozone
20022451664720120043108187Ozone
200124417656120004384150Ozone
20002451904483004177179Ozone
1999214123582760048119177Ozone
1998209129552230045105195Ozone
199721415645130004093150Ozone
19962141574872004087187Ozone
1995214146472010044100195Ozone
1994212126552650046112185Ozone
199321213859150004493136Ozone
19922041604040004074129Ozone
1991213137462460045112161Ozone
1990212133452860044119182Ozone
1989213140482320044108159Ozone
19881991064224243049159212Ozone
19872571625332100044119200Ozone
1986363263633151034101204Ozone
198535026656262003590161Ozone
198436227160256003793197Ozone
1983345254493480035112195NO2
19823582487422131040101201Ozone
198136527755294003897169Ozone
19803642645728123035108237NO2

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 Kentucky with a similar median AQI in 2025

All monitored counties in Kentucky

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