EnviroNearby

Kennebec County, Maine air quality history

Daily Air Quality Index summaries from EPA monitors in Kennebec, Maine, 1980–2025.

85%
Good days in 2025
34
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 Kennebec, Maine on 365 days. 311 of those days (85%) were in the Good range, and the median daily AQI was 34. That median is about the same as the typical monitored county in Maine (median 34 across 11 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 189 days. Across the years with fuller monitoring, the share of Good days rose: an average of 79% in 1980–1982 versus 84% 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 103 of 139 days1980: Moderate 19 of 139 days1980: Unhealthy for Sensitive Groups 13 of 139 days1980: Unhealthy 4 of 139 days19801981: Good 133 of 159 days1981: Moderate 19 of 159 days1981: Unhealthy for Sensitive Groups 2 of 159 days1981: Unhealthy 5 of 159 days1982: Good 133 of 167 days1982: Moderate 26 of 167 days1982: Unhealthy for Sensitive Groups 4 of 167 days1982: Unhealthy 3 of 167 days1982: Very Unhealthy 1 of 167 days1983: Good 160 of 212 days1983: Moderate 34 of 212 days1983: Unhealthy for Sensitive Groups 12 of 212 days1983: Unhealthy 4 of 212 days1983: Very Unhealthy 2 of 212 days1984: Good 194 of 250 days1984: Moderate 35 of 250 days1984: Unhealthy for Sensitive Groups 13 of 250 days1984: Unhealthy 8 of 250 days1985: Good 191 of 253 days1985: Moderate 43 of 253 days1985: Unhealthy for Sensitive Groups 13 of 253 days1985: Unhealthy 5 of 253 days1985: Very Unhealthy 1 of 253 days19851986: Good 226 of 252 days1986: Moderate 22 of 252 days1986: Unhealthy for Sensitive Groups 4 of 252 days1987: Good 238 of 270 days1987: Moderate 26 of 270 days1987: Unhealthy for Sensitive Groups 4 of 270 days1987: Unhealthy 2 of 270 days1988: Good 201 of 257 days1988: Moderate 30 of 257 days1988: Unhealthy for Sensitive Groups 16 of 257 days1988: Unhealthy 7 of 257 days1988: Very Unhealthy 3 of 257 days1989: Good 194 of 239 days1989: Moderate 31 of 239 days1989: Unhealthy for Sensitive Groups 11 of 239 days1989: Unhealthy 3 of 239 days1990: Good 195 of 239 days1990: Moderate 30 of 239 days1990: Unhealthy for Sensitive Groups 11 of 239 days1990: Unhealthy 3 of 239 days19901991: Good 224 of 265 days1991: Moderate 28 of 265 days1991: Unhealthy for Sensitive Groups 9 of 265 days1991: Unhealthy 3 of 265 days1991: Very Unhealthy 1 of 265 days1992: Good 257 of 293 days1992: Moderate 22 of 293 days1992: Unhealthy for Sensitive Groups 11 of 293 days1992: Unhealthy 3 of 293 days1993: Good 258 of 290 days1993: Moderate 26 of 290 days1993: Unhealthy for Sensitive Groups 4 of 290 days1993: Unhealthy 2 of 290 days1994: Good 265 of 297 days1994: Moderate 26 of 297 days1994: Unhealthy for Sensitive Groups 5 of 297 days1994: Unhealthy 1 of 297 days1995: Good 218 of 240 days1995: Moderate 16 of 240 days1995: Unhealthy for Sensitive Groups 6 of 240 days19951996: Good 219 of 243 days1996: Moderate 19 of 243 days1996: Unhealthy for Sensitive Groups 4 of 243 days1996: Unhealthy 1 of 243 days1997: Good 199 of 227 days1997: Moderate 20 of 227 days1997: Unhealthy for Sensitive Groups 6 of 227 days1997: Unhealthy 2 of 227 days1998: Good 183 of 215 days1998: Moderate 25 of 215 days1998: Unhealthy for Sensitive Groups 4 of 215 days1998: Unhealthy 3 of 215 days1999: Good 177 of 212 days1999: Moderate 24 of 212 days1999: Unhealthy for Sensitive Groups 10 of 212 days1999: Unhealthy 1 of 212 days2000: Good 193 of 212 days2000: Moderate 18 of 212 days2000: Unhealthy for Sensitive Groups 1 of 212 days20002001: Good 175 of 208 days2001: Moderate 19 of 208 days2001: Unhealthy for Sensitive Groups 11 of 208 days2001: Unhealthy 3 of 208 days2002: Good 241 of 268 days2002: Moderate 15 of 268 days2002: Unhealthy for Sensitive Groups 8 of 268 days2002: Unhealthy 4 of 268 days2003: Good 267 of 287 days2003: Moderate 18 of 287 days2003: Unhealthy for Sensitive Groups 1 of 287 days2003: Unhealthy 1 of 287 days2004: Good 189 of 209 days2004: Moderate 16 of 209 days2004: Unhealthy for Sensitive Groups 4 of 209 days2005: Good 190 of 213 days2005: Moderate 20 of 213 days2005: Unhealthy for Sensitive Groups 3 of 213 days20052006: Good 192 of 212 days2006: Moderate 18 of 212 days2006: Unhealthy for Sensitive Groups 2 of 212 days2007: Good 188 of 209 days2007: Moderate 11 of 209 days2007: Unhealthy for Sensitive Groups 9 of 209 days2007: Unhealthy 1 of 209 days2008: Good 193 of 211 days2008: Moderate 17 of 211 days2008: Unhealthy for Sensitive Groups 1 of 211 days2009: Good 201 of 212 days2009: Moderate 10 of 212 days2009: Unhealthy for Sensitive Groups 1 of 212 days2010: Good 222 of 237 days2010: Moderate 14 of 237 days2010: Unhealthy for Sensitive Groups 1 of 237 days20102011: Good 195 of 211 days2011: Moderate 16 of 211 days2012: Good 297 of 308 days2012: Moderate 11 of 308 days2013: Good 349 of 361 days2013: Moderate 11 of 361 days2013: Unhealthy for Sensitive Groups 1 of 361 days2014: Good 279 of 286 days2014: Moderate 7 of 286 days2015: Good 216 of 237 days2015: Moderate 21 of 237 days20152016: Good 291 of 309 days2016: Moderate 18 of 309 days2017: Good 342 of 360 days2017: Moderate 18 of 360 days2018: Good 339 of 360 days2018: Moderate 21 of 360 days2019: Good 352 of 361 days2019: Moderate 9 of 361 days2020: Good 221 of 230 days2020: Moderate 9 of 230 days20202021: Good 226 of 244 days2021: Moderate 17 of 244 days2021: Unhealthy for Sensitive Groups 1 of 244 days2022: Good 194 of 203 days2022: Moderate 9 of 203 days2023: Good 242 of 299 days2023: Moderate 57 of 299 days2024: Good 310 of 366 days2024: Moderate 56 of 366 days2025: Good 311 of 365 days2025: Moderate 54 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 1151981: 90th percentile AQI 711982: 90th percentile AQI 741983: 90th percentile AQI 971984: 90th percentile AQI 971985: 90th percentile AQI 801986: 90th percentile AQI 511987: 90th percentile AQI 571988: 90th percentile AQI 1051989: 90th percentile AQI 741990: 90th percentile AQI 711991: 90th percentile AQI 711992: 90th percentile AQI 611993: 90th percentile AQI 511994: 90th percentile AQI 541995: 90th percentile AQI 491996: 90th percentile AQI 501997: 90th percentile AQI 581998: 90th percentile AQI 631999: 90th percentile AQI 612000: 90th percentile AQI 492001: 90th percentile AQI 772002: 90th percentile AQI 512003: 90th percentile AQI 472004: 90th percentile AQI 502005: 90th percentile AQI 512006: 90th percentile AQI 502007: 90th percentile AQI 542008: 90th percentile AQI 492009: 90th percentile AQI 482010: 90th percentile AQI 472011: 90th percentile AQI 492012: 90th percentile AQI 442013: 90th percentile AQI 442014: 90th percentile AQI 432015: 90th percentile AQI 492016: 90th percentile AQI 472017: 90th percentile AQI 442018: 90th percentile AQI 472019: 90th percentile AQI 442020: 90th percentile AQI 452021: 90th percentile AQI 472022: 90th percentile AQI 462023: 90th percentile AQI 592024: 90th percentile AQI 532025: 90th percentile AQI 551980: Median AQI 371981: Median AQI 371982: Median AQI 381983: Median AQI 381984: Median AQI 371985: Median AQI 381986: Median AQI 351987: Median AQI 341988: Median AQI 371989: Median AQI 391990: Median AQI 371991: Median AQI 351992: Median AQI 341993: Median AQI 311994: Median AQI 331995: Median AQI 311996: Median AQI 331997: Median AQI 371998: Median AQI 391999: Median AQI 352000: Median AQI 322001: Median AQI 382002: Median AQI 312003: Median AQI 352004: Median AQI 302005: Median AQI 332006: Median AQI 332007: Median AQI 332008: Median AQI 342009: Median AQI 312010: Median AQI 362011: Median AQI 312012: Median AQI 292013: Median AQI 302014: Median AQI 292015: Median AQI 362016: Median AQI 312017: Median AQI 312018: Median AQI 302019: Median AQI 292020: Median AQI 352021: Median AQI 332022: Median AQI 302023: Median AQI 372024: Median AQI 352025: Median AQI 341980198519901995200020052010201520202025
  • 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)18952%
Ozone17648%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365311540000345596PM2.5
2024366310560000355377PM2.5
2023299242570000375992PM2.5
202220319490000304684Ozone
20212442261710003347125Ozone
202023022190000354567Ozone
201936135290000294470Ozone
2018360339210000304790Ozone
20173603421800003144100Ozone
2016309291180000314784Ozone
2015237216210000364993Ozone
201428627970000294387Ozone
20133613491110003044108Ozone
2012308297110000294490Ozone
2011211195160000314997Ozone
20102372221410003647129Ozone
20092122011010003148105Ozone
20082111931710003449101Ozone
20072091881191003354156Ozone
20062121921820003350119Ozone
20052131902030003351143Ozone
20042091891640003050147Ozone
20032872671811003547151Ozone
20022682411584003151172Ozone
200120817519113003877179Ozone
20002121931810003249115Ozone
199921217724101003561154Ozone
19982151832543003963174Ozone
19972271992062003758179Ozone
19962432191941003350154Ozone
19952402181660003149133Ozone
19942972652651003354172Ozone
19932902582642003151159Ozone
199229325722113003461192Ozone
19912652242893103571210Ozone
199023919530113003771179Ozone
198923919431113003974187Ozone
1988257201301673037105224Ozone
19872702382642003457185Ozone
19862522262240003551150Ozone
198525319143135103880208Ozone
198425019435138003797182Ozone
198321216034124203897214Ozone
19821671332643103874204Ozone
19811591331925003771195Ozone
1980139103191340037115190Ozone

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 Maine with a similar median AQI in 2025

All monitored counties in Maine

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