EnviroNearby

Boyd County, Kentucky air quality history

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

80%
Good days in 2025
39
Median daily AQI, 2025
0
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 Boyd, Kentucky on 365 days. 292 of those days (80%) 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 fine particles (PM2.5) on 200 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 71% in 1980–1982 versus 73% 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 258 of 364 days1980: Moderate 78 of 364 days1980: Unhealthy for Sensitive Groups 23 of 364 days1980: Unhealthy 4 of 364 days1980: Very Unhealthy 1 of 364 days19801981: Good 270 of 365 days1981: Moderate 79 of 365 days1981: Unhealthy for Sensitive Groups 12 of 365 days1981: Unhealthy 4 of 365 days1982: Good 251 of 365 days1982: Moderate 83 of 365 days1982: Unhealthy for Sensitive Groups 24 of 365 days1982: Unhealthy 7 of 365 days1983: Good 223 of 365 days1983: Moderate 92 of 365 days1983: Unhealthy for Sensitive Groups 31 of 365 days1983: Unhealthy 15 of 365 days1983: Very Unhealthy 4 of 365 days1984: Good 219 of 366 days1984: Moderate 105 of 366 days1984: Unhealthy for Sensitive Groups 32 of 366 days1984: Unhealthy 10 of 366 days1985: Good 242 of 365 days1985: Moderate 85 of 365 days1985: Unhealthy for Sensitive Groups 32 of 365 days1985: Unhealthy 5 of 365 days1985: Very Unhealthy 1 of 365 days19851986: Good 258 of 364 days1986: Moderate 84 of 364 days1986: Unhealthy for Sensitive Groups 19 of 364 days1986: Unhealthy 2 of 364 days1986: Very Unhealthy 1 of 364 days1987: Good 222 of 365 days1987: Moderate 100 of 365 days1987: Unhealthy for Sensitive Groups 28 of 365 days1987: Unhealthy 12 of 365 days1987: Very Unhealthy 3 of 365 days1988: Good 241 of 364 days1988: Moderate 77 of 364 days1988: Unhealthy for Sensitive Groups 22 of 364 days1988: Unhealthy 16 of 364 days1988: Very Unhealthy 8 of 364 days1989: Good 268 of 364 days1989: Moderate 74 of 364 days1989: Unhealthy for Sensitive Groups 14 of 364 days1989: Unhealthy 7 of 364 days1989: Very Unhealthy 1 of 364 days1990: Good 255 of 365 days1990: Moderate 72 of 365 days1990: Unhealthy for Sensitive Groups 29 of 365 days1990: Unhealthy 6 of 365 days1990: Very Unhealthy 3 of 365 days19901991: Good 294 of 364 days1991: Moderate 64 of 364 days1991: Unhealthy for Sensitive Groups 6 of 364 days1992: Good 287 of 366 days1992: Moderate 68 of 366 days1992: Unhealthy for Sensitive Groups 9 of 366 days1992: Unhealthy 2 of 366 days1993: Good 255 of 365 days1993: Moderate 92 of 365 days1993: Unhealthy for Sensitive Groups 11 of 365 days1993: Unhealthy 7 of 365 days1994: Good 264 of 365 days1994: Moderate 81 of 365 days1994: Unhealthy for Sensitive Groups 15 of 365 days1994: Unhealthy 4 of 365 days1994: Very Unhealthy 1 of 365 days1995: Good 260 of 365 days1995: Moderate 74 of 365 days1995: Unhealthy for Sensitive Groups 23 of 365 days1995: Unhealthy 8 of 365 days19951996: Good 282 of 366 days1996: Moderate 67 of 366 days1996: Unhealthy for Sensitive Groups 16 of 366 days1996: Unhealthy 1 of 366 days1997: Good 292 of 365 days1997: Moderate 61 of 365 days1997: Unhealthy for Sensitive Groups 8 of 365 days1997: Unhealthy 3 of 365 days1997: Very Unhealthy 1 of 365 days1998: Good 293 of 365 days1998: Moderate 57 of 365 days1998: Unhealthy for Sensitive Groups 12 of 365 days1998: Unhealthy 3 of 365 days1999: Good 192 of 365 days1999: Moderate 134 of 365 days1999: Unhealthy for Sensitive Groups 31 of 365 days1999: Unhealthy 8 of 365 days2000: Good 200 of 366 days2000: Moderate 149 of 366 days2000: Unhealthy for Sensitive Groups 17 of 366 days20002001: Good 199 of 365 days2001: Moderate 142 of 365 days2001: Unhealthy for Sensitive Groups 22 of 365 days2001: Unhealthy 2 of 365 days2002: Good 188 of 365 days2002: Moderate 125 of 365 days2002: Unhealthy for Sensitive Groups 30 of 365 days2002: Unhealthy 21 of 365 days2002: Very Unhealthy 1 of 365 days2003: Good 200 of 362 days2003: Moderate 136 of 362 days2003: Unhealthy for Sensitive Groups 20 of 362 days2003: Unhealthy 5 of 362 days2003: Very Unhealthy 1 of 362 days2004: Good 231 of 361 days2004: Moderate 128 of 361 days2004: Unhealthy for Sensitive Groups 2 of 361 days2005: Good 188 of 363 days2005: Moderate 150 of 363 days2005: Unhealthy for Sensitive Groups 24 of 363 days2005: Unhealthy 1 of 363 days20052006: Good 195 of 339 days2006: Moderate 133 of 339 days2006: Unhealthy for Sensitive Groups 10 of 339 days2006: Unhealthy 1 of 339 days2007: Good 95 of 365 days2007: Moderate 254 of 365 days2007: Unhealthy for Sensitive Groups 16 of 365 days2008: Good 154 of 366 days2008: Moderate 208 of 366 days2008: Unhealthy for Sensitive Groups 4 of 366 days2009: Good 176 of 365 days2009: Moderate 189 of 365 days2010: Good 173 of 365 days2010: Moderate 188 of 365 days2010: Unhealthy for Sensitive Groups 4 of 365 days20102011: Good 203 of 362 days2011: Moderate 156 of 362 days2011: Unhealthy for Sensitive Groups 3 of 362 days2012: Good 221 of 366 days2012: Moderate 137 of 366 days2012: Unhealthy for Sensitive Groups 8 of 366 days2013: Good 248 of 365 days2013: Moderate 116 of 365 days2013: Unhealthy for Sensitive Groups 1 of 365 days2014: Good 247 of 365 days2014: Moderate 117 of 365 days2014: Unhealthy for Sensitive Groups 1 of 365 days2015: Good 195 of 365 days2015: Moderate 167 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days20152016: Good 174 of 365 days2016: Moderate 189 of 365 days2016: Unhealthy for Sensitive Groups 2 of 365 days2017: Good 223 of 365 days2017: Moderate 142 of 365 days2018: Good 245 of 364 days2018: Moderate 118 of 364 days2018: Unhealthy for Sensitive Groups 1 of 364 days2019: Good 259 of 365 days2019: Moderate 106 of 365 days2020: Good 285 of 366 days2020: Moderate 81 of 366 days20202021: Good 231 of 360 days2021: Moderate 128 of 360 days2021: Unhealthy for Sensitive Groups 1 of 360 days2022: Good 252 of 365 days2022: Moderate 113 of 365 days2023: Good 226 of 363 days2023: Moderate 133 of 363 days2023: Unhealthy for Sensitive Groups 2 of 363 days2023: Unhealthy 2 of 363 days2024: Good 275 of 365 days2024: Moderate 90 of 365 days2025: Good 292 of 365 days2025: Moderate 73 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 911981: 90th percentile AQI 841982: 90th percentile AQI 931983: 90th percentile AQI 1151984: 90th percentile AQI 1031985: 90th percentile AQI 1011986: 90th percentile AQI 871987: 90th percentile AQI 1031988: 90th percentile AQI 1191989: 90th percentile AQI 841990: 90th percentile AQI 1021991: 90th percentile AQI 641992: 90th percentile AQI 681993: 90th percentile AQI 861994: 90th percentile AQI 801995: 90th percentile AQI 971996: 90th percentile AQI 801997: 90th percentile AQI 711998: 90th percentile AQI 771999: 90th percentile AQI 1012000: 90th percentile AQI 892001: 90th percentile AQI 902002: 90th percentile AQI 1262003: 90th percentile AQI 912004: 90th percentile AQI 742005: 90th percentile AQI 902006: 90th percentile AQI 802007: 90th percentile AQI 842008: 90th percentile AQI 742009: 90th percentile AQI 672010: 90th percentile AQI 732011: 90th percentile AQI 702012: 90th percentile AQI 672013: 90th percentile AQI 582014: 90th percentile AQI 612015: 90th percentile AQI 672016: 90th percentile AQI 632017: 90th percentile AQI 602018: 90th percentile AQI 592019: 90th percentile AQI 582020: 90th percentile AQI 572021: 90th percentile AQI 612022: 90th percentile AQI 572023: 90th percentile AQI 642024: 90th percentile AQI 562025: 90th percentile AQI 541980: Median AQI 401981: Median AQI 401982: Median AQI 421983: Median AQI 451984: Median AQI 451985: Median AQI 411986: Median AQI 411987: Median AQI 441988: Median AQI 411989: Median AQI 401990: Median AQI 391991: Median AQI 331992: Median AQI 371993: Median AQI 381994: Median AQI 411995: Median AQI 401996: Median AQI 381997: Median AQI 371998: Median AQI 331999: Median AQI 492000: Median AQI 482001: Median AQI 482002: Median AQI 502003: Median AQI 482004: Median AQI 432005: Median AQI 502006: Median AQI 462007: Median AQI 582008: Median AQI 532009: Median AQI 512010: Median AQI 522011: Median AQI 462012: Median AQI 462013: Median AQI 432014: Median AQI 432015: Median AQI 492016: Median AQI 512017: Median AQI 472018: Median AQI 442019: Median AQI 442020: Median AQI 412021: Median AQI 442022: Median AQI 432023: Median AQI 462024: Median AQI 422025: Median AQI 391980198519901995200020052010201520202025
  • 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)20055%
Ozone16244%
Nitrogen dioxide (NO₂)31%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365292730000395497PM2.5
2024365275900000425693PM2.5
202336322613322004664159PM2.5
20223652521130000435780PM2.5
202136023112810004461102PM2.5
2020366285810000415789PM2.5
20193652591060000445874PM2.5
201836424511810004459119PM2.5
20173652231420000476087PM2.5
201636517418920005163126PM2.5
201536519516730004967108PM2.5
201436524711710004361115PM2.5
201336524811610004358119PM2.5
201236622113780004667143PM2.5
201136220315630004670129PM2.5
201036517318840005273119PM2.5
20093651761890000516797PM2.5
200836615420840005374133PM2.5
200736595254160005884133PM2.5
2006339195133101004680154Ozone
2005363188150241005090154Ozone
200436123112820004374129Ozone
2003362200136205104891201Ozone
200236518812530211050126202Ozone
2001365199142222004890164Ozone
2000366200149170004889150Ozone
19993651921343180049101187Ozone
199836529357123003377192CO
19973652926183103771207Ozone
199636628267161003880177Ozone
199536526074238004097195Ozone
199436526481154104180223Ozone
199336525592117003886177Ozone
19923662876892003768159NO2
19913642946460003364129NO2
1990365255722963039102210Ozone
198936426874147104084208Ozone
19883642417722168041119237Ozone
198736522210028123044103226Ozone
198636425884192104187207Ozone
1985365242853251041101205Ozone
198436621910532100045103192NO2
19833652239231154045115207CO
198236525183247004293192Ozone
198136527079124004084179Ozone
198036425878234104091220Ozone

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