EnviroNearby

Hancock County, Maine air quality history

Daily Air Quality Index summaries from EPA monitors in Hancock, Maine, 1982–2025.

91%
Good days in 2025
35
Median daily AQI, 2025
4
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 Hancock, Maine on 365 days. 332 of those days (91%) were in the Good range, and the median daily AQI was 35. 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 ozone on 333 days. Across the years with fuller monitoring, the share of Good days rose: an average of 84% in 1982–1984 versus 89% 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%1982: Good 167 of 187 days1982: Moderate 13 of 187 days1982: Unhealthy for Sensitive Groups 3 of 187 days1982: Unhealthy 4 of 187 days19821983: Good 254 of 325 days1983: Moderate 44 of 325 days1983: Unhealthy for Sensitive Groups 14 of 325 days1983: Unhealthy 12 of 325 days1983: Very Unhealthy 1 of 325 days1984: Good 283 of 329 days1984: Moderate 24 of 329 days1984: Unhealthy for Sensitive Groups 17 of 329 days1984: Unhealthy 5 of 329 days1985: Good 311 of 363 days1985: Moderate 29 of 363 days1985: Unhealthy for Sensitive Groups 16 of 363 days1985: Unhealthy 7 of 363 days1986: Good 301 of 334 days1986: Moderate 22 of 334 days1986: Unhealthy for Sensitive Groups 8 of 334 days1986: Unhealthy 3 of 334 days1987: Good 304 of 350 days1987: Moderate 36 of 350 days1987: Unhealthy for Sensitive Groups 4 of 350 days1987: Unhealthy 5 of 350 days1987: Very Unhealthy 1 of 350 days19871988: Good 247 of 320 days1988: Moderate 40 of 320 days1988: Unhealthy for Sensitive Groups 15 of 320 days1988: Unhealthy 11 of 320 days1988: Very Unhealthy 7 of 320 days1989: Good 236 of 306 days1989: Moderate 61 of 306 days1989: Unhealthy for Sensitive Groups 6 of 306 days1989: Unhealthy 2 of 306 days1989: Very Unhealthy 1 of 306 days1990: Good 295 of 364 days1990: Moderate 55 of 364 days1990: Unhealthy for Sensitive Groups 8 of 364 days1990: Unhealthy 6 of 364 days1991: Good 300 of 360 days1991: Moderate 39 of 360 days1991: Unhealthy for Sensitive Groups 14 of 360 days1991: Unhealthy 4 of 360 days1991: Very Unhealthy 3 of 360 days1992: Good 286 of 339 days1992: Moderate 34 of 339 days1992: Unhealthy for Sensitive Groups 16 of 339 days1992: Unhealthy 3 of 339 days19921993: Good 298 of 340 days1993: Moderate 32 of 340 days1993: Unhealthy for Sensitive Groups 9 of 340 days1993: Unhealthy 1 of 340 days1994: Good 292 of 346 days1994: Moderate 46 of 346 days1994: Unhealthy for Sensitive Groups 8 of 346 days1995: Good 302 of 355 days1995: Moderate 38 of 355 days1995: Unhealthy for Sensitive Groups 10 of 355 days1995: Unhealthy 5 of 355 days1996: Good 271 of 346 days1996: Moderate 59 of 346 days1996: Unhealthy for Sensitive Groups 13 of 346 days1996: Unhealthy 3 of 346 days1997: Good 183 of 250 days1997: Moderate 52 of 250 days1997: Unhealthy for Sensitive Groups 12 of 250 days1997: Unhealthy 3 of 250 days19971998: Good 250 of 340 days1998: Moderate 59 of 340 days1998: Unhealthy for Sensitive Groups 23 of 340 days1998: Unhealthy 5 of 340 days1998: Very Unhealthy 3 of 340 days1999: Good 278 of 358 days1999: Moderate 63 of 358 days1999: Unhealthy for Sensitive Groups 11 of 358 days1999: Unhealthy 5 of 358 days1999: Very Unhealthy 1 of 358 days2000: Good 310 of 361 days2000: Moderate 41 of 361 days2000: Unhealthy for Sensitive Groups 7 of 361 days2000: Unhealthy 3 of 361 days2001: Good 305 of 365 days2001: Moderate 33 of 365 days2001: Unhealthy for Sensitive Groups 18 of 365 days2001: Unhealthy 8 of 365 days2001: Very Unhealthy 1 of 365 days2002: Good 303 of 365 days2002: Moderate 35 of 365 days2002: Unhealthy for Sensitive Groups 19 of 365 days2002: Unhealthy 5 of 365 days2002: Very Unhealthy 3 of 365 days20022003: Good 309 of 365 days2003: Moderate 40 of 365 days2003: Unhealthy for Sensitive Groups 12 of 365 days2003: Unhealthy 4 of 365 days2004: Good 319 of 366 days2004: Moderate 34 of 366 days2004: Unhealthy for Sensitive Groups 13 of 366 days2005: Good 304 of 365 days2005: Moderate 44 of 365 days2005: Unhealthy for Sensitive Groups 14 of 365 days2005: Unhealthy 3 of 365 days2006: Good 310 of 365 days2006: Moderate 43 of 365 days2006: Unhealthy for Sensitive Groups 11 of 365 days2006: Unhealthy 1 of 365 days2007: Good 305 of 361 days2007: Moderate 39 of 361 days2007: Unhealthy for Sensitive Groups 13 of 361 days2007: Unhealthy 4 of 361 days20072008: Good 315 of 366 days2008: Moderate 45 of 366 days2008: Unhealthy for Sensitive Groups 6 of 366 days2009: Good 322 of 365 days2009: Moderate 39 of 365 days2009: Unhealthy for Sensitive Groups 3 of 365 days2009: Unhealthy 1 of 365 days2010: Good 316 of 365 days2010: Moderate 44 of 365 days2010: Unhealthy for Sensitive Groups 3 of 365 days2010: Unhealthy 2 of 365 days2011: Good 329 of 365 days2011: Moderate 32 of 365 days2011: Unhealthy for Sensitive Groups 3 of 365 days2011: Unhealthy 1 of 365 days2012: Good 331 of 366 days2012: Moderate 34 of 366 days2012: Unhealthy for Sensitive Groups 1 of 366 days20122013: Good 325 of 365 days2013: Moderate 37 of 365 days2013: Unhealthy for Sensitive Groups 3 of 365 days2014: Good 341 of 365 days2014: Moderate 23 of 365 days2014: Unhealthy for Sensitive Groups 1 of 365 days2015: Good 315 of 365 days2015: Moderate 47 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days2016: Good 326 of 366 days2016: Moderate 38 of 366 days2016: Unhealthy for Sensitive Groups 2 of 366 days2017: Good 325 of 365 days2017: Moderate 34 of 365 days2017: Unhealthy for Sensitive Groups 5 of 365 days2017: Unhealthy 1 of 365 days20172018: Good 331 of 365 days2018: Moderate 33 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days2019: Good 339 of 365 days2019: Moderate 25 of 365 days2019: Unhealthy for Sensitive Groups 1 of 365 days2020: Good 336 of 366 days2020: Moderate 29 of 366 days2020: Unhealthy for Sensitive Groups 1 of 366 days2021: Good 324 of 365 days2021: Moderate 38 of 365 days2021: Unhealthy for Sensitive Groups 3 of 365 days2022: Good 326 of 361 days2022: Moderate 34 of 361 days2022: Unhealthy for Sensitive Groups 1 of 361 days20222023: Good 314 of 365 days2023: Moderate 51 of 365 days2024: Good 334 of 366 days2024: Moderate 31 of 366 days2024: Unhealthy for Sensitive Groups 1 of 366 days2025: Good 332 of 365 days2025: Moderate 29 of 365 days2025: Unhealthy for Sensitive Groups 4 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 year0501001501982: 90th percentile AQI 511983: 90th percentile AQI 901984: 90th percentile AQI 711985: 90th percentile AQI 741986: 90th percentile AQI 501987: 90th percentile AQI 611988: 90th percentile AQI 1051989: 90th percentile AQI 711990: 90th percentile AQI 711991: 90th percentile AQI 641992: 90th percentile AQI 641993: 90th percentile AQI 561994: 90th percentile AQI 631995: 90th percentile AQI 561996: 90th percentile AQI 741997: 90th percentile AQI 801998: 90th percentile AQI 931999: 90th percentile AQI 672000: 90th percentile AQI 612001: 90th percentile AQI 772002: 90th percentile AQI 872003: 90th percentile AQI 612004: 90th percentile AQI 582005: 90th percentile AQI 612006: 90th percentile AQI 642007: 90th percentile AQI 672008: 90th percentile AQI 612009: 90th percentile AQI 542010: 90th percentile AQI 562011: 90th percentile AQI 502012: 90th percentile AQI 502013: 90th percentile AQI 512014: 90th percentile AQI 482015: 90th percentile AQI 542016: 90th percentile AQI 522017: 90th percentile AQI 512018: 90th percentile AQI 502019: 90th percentile AQI 492020: 90th percentile AQI 502021: 90th percentile AQI 522022: 90th percentile AQI 502023: 90th percentile AQI 542024: 90th percentile AQI 502025: 90th percentile AQI 491982: Median AQI 231983: Median AQI 361984: Median AQI 321985: Median AQI 351986: Median AQI 331987: Median AQI 351988: Median AQI 401989: Median AQI 401990: Median AQI 361991: Median AQI 351992: Median AQI 341993: Median AQI 341994: Median AQI 351995: Median AQI 361996: Median AQI 391997: Median AQI 411998: Median AQI 401999: Median AQI 422000: Median AQI 362001: Median AQI 372002: Median AQI 372003: Median AQI 392004: Median AQI 362005: Median AQI 372006: Median AQI 372007: Median AQI 362008: Median AQI 362009: Median AQI 352010: Median AQI 372011: Median AQI 362012: Median AQI 362013: Median AQI 382014: Median AQI 362015: Median AQI 382016: Median AQI 382017: Median AQI 372018: Median AQI 372019: Median AQI 372020: Median AQI 362021: Median AQI 362022: Median AQI 362023: Median AQI 382024: Median AQI 372025: Median AQI 351982198719921997200220072012201720222025
  • 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
Ozone33391%
Fine particles (PM2.5)329%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253653322940003549133Ozone
20243663343110003750105Ozone
2023365314510000385493Ozone
20223613263410003650112Ozone
20213653243830003652133Ozone
20203663362910003650105Ozone
20193653392510003749105Ozone
20183653313310003750122Ozone
20173653253451003751182Ozone
20163663263820003852122Ozone
20153653154730003854143Ozone
20143653412310003648105Ozone
20133653253730003851129Ozone
20123663313410003650101Ozone
20113653293231003650166Ozone
20103653164432003756159Ozone
20093653223931003554151Ozone
20083663154560003661126Ozone
200736130539134003667182Ozone
200636531043111003764166Ozone
200536530444143003761172Ozone
200436631934130003658147Ozone
200336530940124003961195Ozone
200236530335195303787206Ozone
200136530533188103777202Ozone
20003613104173003661179Ozone
199935827863115104267206Ozone
199834025059235304093206Ozone
199725018352123004180174Ozone
199634627159133003974179Ozone
199535530238105003656197Ozone
19943462924680003563140Ozone
19933402983291003456151Ozone
199233928634163003464185Ozone
199136030039144303564208Ozone
19903642955586003671197Ozone
19893062366162104071203Ozone
19883202474015117040105226Ozone
19873503043645103561205Ozone
19863343012283003350185Ozone
198536331129167003574192Ozone
198432928324175003271190Ozone
1983325254441412103690213Ozone
19821871671334002351187Ozone

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 1982–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem