EnviroNearby

Oldham County, Kentucky air quality history

Daily Air Quality Index summaries from EPA monitors in Oldham, Kentucky, 1981–2025.

88%
Good days in 2025
39
Median daily AQI, 2025
2
Days above 100 in 2025
244
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Oldham, Kentucky on 244 days. 214 of those days (88%) were in the Good range, and the median daily AQI was 39. 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 244 days. Across the years with fuller monitoring, the share of Good days rose: an average of 80% in 1981–1983 versus 83% in 2023–2025.

EPA did not report an AQI for every day of 2025 here (244 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%1981: Good 165 of 169 days1981: Moderate 3 of 169 days1981: Unhealthy for Sensitive Groups 1 of 169 days19811982: Good 142 of 175 days1982: Moderate 29 of 175 days1982: Unhealthy for Sensitive Groups 4 of 175 days1983: Good 112 of 183 days1983: Moderate 32 of 183 days1983: Unhealthy for Sensitive Groups 23 of 183 days1983: Unhealthy 14 of 183 days1983: Very Unhealthy 2 of 183 days1984: Good 122 of 209 days1984: Moderate 51 of 209 days1984: Unhealthy for Sensitive Groups 27 of 209 days1984: Unhealthy 9 of 209 days1985: Good 141 of 212 days1985: Moderate 54 of 212 days1985: Unhealthy for Sensitive Groups 12 of 212 days1985: Unhealthy 4 of 212 days1985: Very Unhealthy 1 of 212 days1986: Good 119 of 204 days1986: Moderate 48 of 204 days1986: Unhealthy for Sensitive Groups 23 of 204 days1986: Unhealthy 11 of 204 days1986: Very Unhealthy 3 of 204 days19861987: Good 98 of 205 days1987: Moderate 68 of 205 days1987: Unhealthy for Sensitive Groups 34 of 205 days1987: Unhealthy 5 of 205 days1988: Good 103 of 200 days1988: Moderate 38 of 200 days1988: Unhealthy for Sensitive Groups 25 of 200 days1988: Unhealthy 30 of 200 days1988: Very Unhealthy 4 of 200 days1989: Good 142 of 212 days1989: Moderate 56 of 212 days1989: Unhealthy for Sensitive Groups 12 of 212 days1989: Unhealthy 2 of 212 days1990: Good 158 of 201 days1990: Moderate 26 of 201 days1990: Unhealthy for Sensitive Groups 13 of 201 days1990: Unhealthy 4 of 201 days1991: Good 124 of 200 days1991: Moderate 47 of 200 days1991: Unhealthy for Sensitive Groups 23 of 200 days1991: Unhealthy 5 of 200 days1991: Very Unhealthy 1 of 200 days19911992: Good 175 of 211 days1992: Moderate 34 of 211 days1992: Unhealthy for Sensitive Groups 2 of 211 days1993: Good 146 of 214 days1993: Moderate 52 of 214 days1993: Unhealthy for Sensitive Groups 12 of 214 days1993: Unhealthy 4 of 214 days1994: Good 122 of 211 days1994: Moderate 55 of 211 days1994: Unhealthy for Sensitive Groups 26 of 211 days1994: Unhealthy 8 of 211 days1995: Good 123 of 205 days1995: Moderate 55 of 205 days1995: Unhealthy for Sensitive Groups 19 of 205 days1995: Unhealthy 8 of 205 days1996: Good 142 of 205 days1996: Moderate 41 of 205 days1996: Unhealthy for Sensitive Groups 18 of 205 days1996: Unhealthy 4 of 205 days19961997: Good 139 of 204 days1997: Moderate 44 of 204 days1997: Unhealthy for Sensitive Groups 18 of 204 days1997: Unhealthy 1 of 204 days1997: Very Unhealthy 2 of 204 days1998: Good 118 of 213 days1998: Moderate 58 of 213 days1998: Unhealthy for Sensitive Groups 26 of 213 days1998: Unhealthy 9 of 213 days1998: Very Unhealthy 2 of 213 days1999: Good 62 of 213 days1999: Moderate 64 of 213 days1999: Unhealthy for Sensitive Groups 55 of 213 days1999: Unhealthy 29 of 213 days1999: Very Unhealthy 3 of 213 days2000: Good 153 of 224 days2000: Moderate 53 of 224 days2000: Unhealthy for Sensitive Groups 14 of 224 days2000: Unhealthy 4 of 224 days2001: Good 145 of 242 days2001: Moderate 69 of 242 days2001: Unhealthy for Sensitive Groups 24 of 242 days2001: Unhealthy 4 of 242 days20012002: Good 158 of 244 days2002: Moderate 49 of 244 days2002: Unhealthy for Sensitive Groups 28 of 244 days2002: Unhealthy 9 of 244 days2003: Good 169 of 245 days2003: Moderate 60 of 245 days2003: Unhealthy for Sensitive Groups 15 of 245 days2003: Unhealthy 1 of 245 days2004: Good 175 of 244 days2004: Moderate 58 of 244 days2004: Unhealthy for Sensitive Groups 11 of 244 days2005: Good 129 of 245 days2005: Moderate 72 of 245 days2005: Unhealthy for Sensitive Groups 40 of 245 days2005: Unhealthy 4 of 245 days2006: Good 152 of 244 days2006: Moderate 72 of 244 days2006: Unhealthy for Sensitive Groups 18 of 244 days2006: Unhealthy 2 of 244 days20062007: Good 130 of 245 days2007: Moderate 81 of 245 days2007: Unhealthy for Sensitive Groups 31 of 245 days2007: Unhealthy 3 of 245 days2008: Good 172 of 240 days2008: Moderate 58 of 240 days2008: Unhealthy for Sensitive Groups 9 of 240 days2008: Unhealthy 1 of 240 days2009: Good 201 of 237 days2009: Moderate 35 of 237 days2009: Unhealthy for Sensitive Groups 1 of 237 days2010: Good 138 of 243 days2010: Moderate 89 of 243 days2010: Unhealthy for Sensitive Groups 15 of 243 days2010: Unhealthy 1 of 243 days2011: Good 152 of 245 days2011: Moderate 71 of 245 days2011: Unhealthy for Sensitive Groups 16 of 245 days2011: Unhealthy 6 of 245 days20112012: Good 154 of 245 days2012: Moderate 69 of 245 days2012: Unhealthy for Sensitive Groups 15 of 245 days2012: Unhealthy 6 of 245 days2012: Very Unhealthy 1 of 245 days2013: Good 209 of 243 days2013: Moderate 33 of 243 days2013: Unhealthy for Sensitive Groups 1 of 243 days2014: Good 205 of 245 days2014: Moderate 39 of 245 days2014: Unhealthy for Sensitive Groups 1 of 245 days2015: Good 164 of 191 days2015: Moderate 23 of 191 days2015: Unhealthy for Sensitive Groups 4 of 191 days2016: Good 204 of 241 days2016: Moderate 34 of 241 days2016: Unhealthy for Sensitive Groups 3 of 241 days20162017: Good 208 of 237 days2017: Moderate 28 of 237 days2017: Unhealthy for Sensitive Groups 1 of 237 days2018: Good 214 of 243 days2018: Moderate 28 of 243 days2018: Unhealthy for Sensitive Groups 1 of 243 days2019: Good 203 of 242 days2019: Moderate 38 of 242 days2019: Unhealthy for Sensitive Groups 1 of 242 days2020: Good 218 of 239 days2020: Moderate 21 of 239 days2021: Good 216 of 244 days2021: Moderate 27 of 244 days2021: Unhealthy for Sensitive Groups 1 of 244 days20212022: Good 221 of 245 days2022: Moderate 22 of 245 days2022: Unhealthy for Sensitive Groups 2 of 245 days2023: Good 195 of 242 days2023: Moderate 46 of 242 days2023: Unhealthy for Sensitive Groups 1 of 242 days2024: Good 194 of 242 days2024: Moderate 43 of 242 days2024: Unhealthy for Sensitive Groups 5 of 242 days2025: Good 214 of 244 days2025: Moderate 28 of 244 days2025: Unhealthy for Sensitive Groups 2 of 244 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 year0501001502001981: 90th percentile AQI 301982: 90th percentile AQI 711983: 90th percentile AQI 1431984: 90th percentile AQI 1221985: 90th percentile AQI 931986: 90th percentile AQI 1431987: 90th percentile AQI 1151988: 90th percentile AQI 1721989: 90th percentile AQI 931990: 90th percentile AQI 871991: 90th percentile AQI 1151992: 90th percentile AQI 611993: 90th percentile AQI 931994: 90th percentile AQI 1191995: 90th percentile AQI 1191996: 90th percentile AQI 1011997: 90th percentile AQI 1011998: 90th percentile AQI 1291999: 90th percentile AQI 1612000: 90th percentile AQI 932001: 90th percentile AQI 1082002: 90th percentile AQI 1192003: 90th percentile AQI 842004: 90th percentile AQI 742005: 90th percentile AQI 1192006: 90th percentile AQI 1002007: 90th percentile AQI 1122008: 90th percentile AQI 802009: 90th percentile AQI 582010: 90th percentile AQI 902011: 90th percentile AQI 1002012: 90th percentile AQI 972013: 90th percentile AQI 582014: 90th percentile AQI 612015: 90th percentile AQI 542016: 90th percentile AQI 642017: 90th percentile AQI 542018: 90th percentile AQI 542019: 90th percentile AQI 582020: 90th percentile AQI 492021: 90th percentile AQI 542022: 90th percentile AQI 502023: 90th percentile AQI 642024: 90th percentile AQI 612025: 90th percentile AQI 511981: Median AQI 121982: Median AQI 351983: Median AQI 381984: Median AQI 481985: Median AQI 421986: Median AQI 461987: Median AQI 541988: Median AQI 501989: Median AQI 441990: Median AQI 331991: Median AQI 441992: Median AQI 371993: Median AQI 431994: Median AQI 451995: Median AQI 461996: Median AQI 441997: Median AQI 431998: Median AQI 481999: Median AQI 902000: Median AQI 442001: Median AQI 462002: Median AQI 442003: Median AQI 432004: Median AQI 442005: Median AQI 492006: Median AQI 462007: Median AQI 492008: Median AQI 442009: Median AQI 392010: Median AQI 482011: Median AQI 462012: Median AQI 472013: Median AQI 402014: Median AQI 422015: Median AQI 392016: Median AQI 412017: Median AQI 402018: Median AQI 382019: Median AQI 422020: Median AQI 382021: Median AQI 392022: Median AQI 412023: Median AQI 422024: Median AQI 432025: Median AQI 391981198619911996200120062011201620212025
  • 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
Ozone244100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20252442142820003951108Ozone
20242421944350004361136Ozone
20232421954610004264105Ozone
20222452212220004150112Ozone
20212442162710003954105Ozone
2020239218210000384997Ozone
20192422033810004258105Ozone
20182432142810003854108Ozone
20172372082810004054119Ozone
20162412043430004164112Ozone
20151911642340003954129Ozone
20142452053910004261101Ozone
20132432093310004058108Ozone
201224515469156104797204Ozone
2011245152711660046100179Ozone
201024313889151004890161Ozone
20092372013510003958101Ozone
20082401725891004480159Ozone
2007245130813130049112156Ozone
2006244152721820046100151Ozone
2005245129724040049119172Ozone
200424417558110004474126Ozone
200324516960151004384156Ozone
2002244158492890044119200Ozone
2001242145692440046108166Ozone
200022415353144004493174Ozone
1999213626455293090161204Ozone
1998213118582692048129207Ozone
1997204139441812043101204Ozone
1996205142411840044101197Ozone
1995205123551980046119166Ozone
1994211122552680045119185Ozone
199321414652124004393179Ozone
19922111753420003761122Ozone
1991200124472351044115201Ozone
199020115826134003387200Ozone
198921214256122004493174Ozone
19882001033825304050172219Ozone
198720598683450054115161Ozone
19862041194823113046143215Ozone
198521214154124104293202Ozone
1984209122512790048122190Ozone
19831831123223142038143210Ozone
19821751422940003571112Ozone
1981169165310001230105Ozone

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 1981–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem