EnviroNearby

Hampshire County, Massachusetts air quality history

Daily Air Quality Index summaries from EPA monitors in Hampshire, Massachusetts, 1981–2025.

85%
Good days in 2025
36
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 Hampshire, Massachusetts on 365 days. 312 of those days (85%) were in the Good range, and the median daily AQI was 36. That median is about the same as the typical monitored county in Massachusetts (median 38 across 13 counties), and lower than the typical monitored U.S. county (40). The main pollutant was ozone on 289 days. Across the years with fuller monitoring, the share of Good days rose: an average of 61% in 1981–1983 versus 85% 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%1981: Good 114 of 163 days1981: Moderate 32 of 163 days1981: Unhealthy for Sensitive Groups 9 of 163 days1981: Unhealthy 4 of 163 days1981: Very Unhealthy 4 of 163 days19811982: Good 119 of 196 days1982: Moderate 50 of 196 days1982: Unhealthy for Sensitive Groups 16 of 196 days1982: Unhealthy 7 of 196 days1982: Very Unhealthy 4 of 196 days1983: Good 100 of 196 days1983: Moderate 48 of 196 days1983: Unhealthy for Sensitive Groups 26 of 196 days1983: Unhealthy 13 of 196 days1983: Very Unhealthy 9 of 196 days1984: Good 132 of 197 days1984: Moderate 33 of 197 days1984: Unhealthy for Sensitive Groups 13 of 197 days1984: Unhealthy 15 of 197 days1984: Very Unhealthy 4 of 197 days1985: Good 146 of 212 days1985: Moderate 35 of 212 days1985: Unhealthy for Sensitive Groups 20 of 212 days1985: Unhealthy 9 of 212 days1985: Very Unhealthy 2 of 212 days1986: Good 298 of 365 days1986: Moderate 43 of 365 days1986: Unhealthy for Sensitive Groups 15 of 365 days1986: Unhealthy 9 of 365 days19861987: Good 289 of 365 days1987: Moderate 52 of 365 days1987: Unhealthy for Sensitive Groups 17 of 365 days1987: Unhealthy 7 of 365 days1988: Good 265 of 364 days1988: Moderate 50 of 364 days1988: Unhealthy for Sensitive Groups 21 of 364 days1988: Unhealthy 14 of 364 days1988: Very Unhealthy 14 of 364 days1989: Good 263 of 362 days1989: Moderate 66 of 362 days1989: Unhealthy for Sensitive Groups 25 of 362 days1989: Unhealthy 5 of 362 days1989: Very Unhealthy 3 of 362 days1990: Good 254 of 363 days1990: Moderate 73 of 363 days1990: Unhealthy for Sensitive Groups 23 of 363 days1990: Unhealthy 11 of 363 days1990: Very Unhealthy 2 of 363 days1991: Good 279 of 360 days1991: Moderate 54 of 360 days1991: Unhealthy for Sensitive Groups 13 of 360 days1991: Unhealthy 8 of 360 days1991: Very Unhealthy 6 of 360 days19911992: Good 290 of 358 days1992: Moderate 35 of 358 days1992: Unhealthy for Sensitive Groups 23 of 358 days1992: Unhealthy 8 of 358 days1992: Very Unhealthy 2 of 358 days1993: Good 278 of 364 days1993: Moderate 55 of 364 days1993: Unhealthy for Sensitive Groups 21 of 364 days1993: Unhealthy 9 of 364 days1993: Very Unhealthy 1 of 364 days1994: Good 263 of 360 days1994: Moderate 57 of 360 days1994: Unhealthy for Sensitive Groups 28 of 360 days1994: Unhealthy 10 of 360 days1994: Very Unhealthy 2 of 360 days1995: Good 304 of 365 days1995: Moderate 37 of 365 days1995: Unhealthy for Sensitive Groups 17 of 365 days1995: Unhealthy 6 of 365 days1995: Very Unhealthy 1 of 365 days1996: Good 305 of 366 days1996: Moderate 48 of 366 days1996: Unhealthy for Sensitive Groups 9 of 366 days1996: Unhealthy 4 of 366 days19961997: Good 279 of 365 days1997: Moderate 54 of 365 days1997: Unhealthy for Sensitive Groups 23 of 365 days1997: Unhealthy 5 of 365 days1997: Very Unhealthy 4 of 365 days1998: Good 273 of 365 days1998: Moderate 62 of 365 days1998: Unhealthy for Sensitive Groups 25 of 365 days1998: Unhealthy 4 of 365 days1998: Very Unhealthy 1 of 365 days1999: Good 272 of 365 days1999: Moderate 69 of 365 days1999: Unhealthy for Sensitive Groups 15 of 365 days1999: Unhealthy 8 of 365 days1999: Very Unhealthy 1 of 365 days2000: Good 281 of 352 days2000: Moderate 63 of 352 days2000: Unhealthy for Sensitive Groups 6 of 352 days2000: Unhealthy 2 of 352 days2001: Good 260 of 365 days2001: Moderate 78 of 365 days2001: Unhealthy for Sensitive Groups 15 of 365 days2001: Unhealthy 10 of 365 days2001: Very Unhealthy 2 of 365 days20012002: Good 270 of 365 days2002: Moderate 73 of 365 days2002: Unhealthy for Sensitive Groups 12 of 365 days2002: Unhealthy 8 of 365 days2002: Very Unhealthy 2 of 365 days2003: Good 287 of 365 days2003: Moderate 72 of 365 days2003: Unhealthy for Sensitive Groups 6 of 365 days2004: Good 285 of 366 days2004: Moderate 69 of 366 days2004: Unhealthy for Sensitive Groups 9 of 366 days2004: Unhealthy 3 of 366 days2005: Good 257 of 365 days2005: Moderate 86 of 365 days2005: Unhealthy for Sensitive Groups 15 of 365 days2005: Unhealthy 7 of 365 days2006: Good 274 of 365 days2006: Moderate 77 of 365 days2006: Unhealthy for Sensitive Groups 10 of 365 days2006: Unhealthy 3 of 365 days2006: Very Unhealthy 1 of 365 days20062007: Good 152 of 365 days2007: Moderate 187 of 365 days2007: Unhealthy for Sensitive Groups 19 of 365 days2007: Unhealthy 6 of 365 days2007: Very Unhealthy 1 of 365 days2008: Good 150 of 365 days2008: Moderate 203 of 365 days2008: Unhealthy for Sensitive Groups 11 of 365 days2008: Unhealthy 1 of 365 days2009: Good 213 of 365 days2009: Moderate 143 of 365 days2009: Unhealthy for Sensitive Groups 9 of 365 days2010: Good 273 of 365 days2010: Moderate 83 of 365 days2010: Unhealthy for Sensitive Groups 8 of 365 days2010: Unhealthy 1 of 365 days2011: Good 271 of 365 days2011: Moderate 91 of 365 days2011: Unhealthy for Sensitive Groups 3 of 365 days20112012: Good 281 of 366 days2012: Moderate 74 of 366 days2012: Unhealthy for Sensitive Groups 11 of 366 days2013: Good 230 of 365 days2013: Moderate 133 of 365 days2013: Unhealthy for Sensitive Groups 2 of 365 days2014: Good 228 of 365 days2014: Moderate 137 of 365 days2015: Good 295 of 361 days2015: Moderate 62 of 361 days2015: Unhealthy for Sensitive Groups 4 of 361 days2016: Good 302 of 359 days2016: Moderate 53 of 359 days2016: Unhealthy for Sensitive Groups 3 of 359 days2016: Unhealthy 1 of 359 days20162017: Good 310 of 365 days2017: Moderate 52 of 365 days2017: Unhealthy for Sensitive Groups 3 of 365 days2018: Good 282 of 363 days2018: Moderate 79 of 363 days2018: Unhealthy for Sensitive Groups 2 of 363 days2019: Good 296 of 364 days2019: Moderate 68 of 364 days2020: Good 300 of 366 days2020: Moderate 66 of 366 days2021: Good 307 of 352 days2021: Moderate 45 of 352 days20212022: Good 267 of 365 days2022: Moderate 98 of 365 days2023: Good 292 of 365 days2023: Moderate 67 of 365 days2023: Unhealthy for Sensitive Groups 6 of 365 days2024: Good 324 of 366 days2024: Moderate 40 of 366 days2024: Unhealthy for Sensitive Groups 2 of 366 days2025: Good 312 of 365 days2025: Moderate 49 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 year0501001502001981: 90th percentile AQI 1081982: 90th percentile AQI 1151983: 90th percentile AQI 1561984: 90th percentile AQI 1471985: 90th percentile AQI 1151986: 90th percentile AQI 771987: 90th percentile AQI 841988: 90th percentile AQI 1261989: 90th percentile AQI 971990: 90th percentile AQI 1001991: 90th percentile AQI 871992: 90th percentile AQI 931993: 90th percentile AQI 871994: 90th percentile AQI 1021995: 90th percentile AQI 801996: 90th percentile AQI 671997: 90th percentile AQI 901998: 90th percentile AQI 931999: 90th percentile AQI 842000: 90th percentile AQI 652001: 90th percentile AQI 872002: 90th percentile AQI 792003: 90th percentile AQI 672004: 90th percentile AQI 712005: 90th percentile AQI 802006: 90th percentile AQI 742007: 90th percentile AQI 812008: 90th percentile AQI 802009: 90th percentile AQI 672010: 90th percentile AQI 662011: 90th percentile AQI 602012: 90th percentile AQI 612013: 90th percentile AQI 632014: 90th percentile AQI 602015: 90th percentile AQI 582016: 90th percentile AQI 552017: 90th percentile AQI 542018: 90th percentile AQI 582019: 90th percentile AQI 542020: 90th percentile AQI 542021: 90th percentile AQI 522022: 90th percentile AQI 572023: 90th percentile AQI 552024: 90th percentile AQI 512025: 90th percentile AQI 541981: Median AQI 391982: Median AQI 461983: Median AQI 501984: Median AQI 431985: Median AQI 421986: Median AQI 371987: Median AQI 371988: Median AQI 401989: Median AQI 391990: Median AQI 431991: Median AQI 391992: Median AQI 391993: Median AQI 381994: Median AQI 411995: Median AQI 371996: Median AQI 361997: Median AQI 391998: Median AQI 381999: Median AQI 412000: Median AQI 382001: Median AQI 422002: Median AQI 392003: Median AQI 382004: Median AQI 392005: Median AQI 432006: Median AQI 382007: Median AQI 522008: Median AQI 532009: Median AQI 442010: Median AQI 392011: Median AQI 412012: Median AQI 382013: Median AQI 442014: Median AQI 442015: Median AQI 372016: Median AQI 382017: Median AQI 382018: Median AQI 402019: Median AQI 412020: Median AQI 392021: Median AQI 352022: Median AQI 422023: Median AQI 382024: Median AQI 352025: Median AQI 361981198619911996200120062011201620212025
  • 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
Ozone28979%
Fine particles (PM2.5)7521%
Coarse particles (PM10)1<1%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253653124940003654117Ozone
20243663244020003551112Ozone
20233652926760003855138Ozone
2022365267980000425797Ozone
2021352307450000355296Ozone
2020366300660000395484PM2.5
2019364296680000415493Ozone
20183632827920004058122Ozone
20173653105230003854122Ozone
20163593025331003855159Ozone
20153612956240003758108Ozone
201436522813700004460100PM2.5
201336523013320004463115PM2.5
201236628174110003861140Ozone
20113652719130004160147Ozone
20103652738381003966159Ozone
200936521314390004467129PM2.5
2008365150203111005380174PM2.5
2007365152187196105281204PM2.5
200636527477103103874205Ozone
200536525786157004380190Ozone
20043662856993003971164Ozone
20033652877260003867147Ozone
200236527073128203979205Ozone
2001365260781510204287215Ozone
20003522816362003865164Ozone
199936527269158104184201Ozone
199836527362254103893205Ozone
199736527954235403990215Ozone
19963663054894003667174Ozone
199536530437176103780205Ozone
19943602635728102041102205Ozone
199336427855219103887202Ozone
199235829035238203993206Ozone
199136027954138603987230Ozone
19903632547323112043100213Ozone
198936226366255303997230Ozone
198836426550211414040126252Ozone
198736528952177003784172Ozone
198636529843159003777195Ozone
1985212146352092042115212Ozone
19841971323313154043147234Ozone
19831961004826139050156235Ozone
1982196119501674046115226Ozone
198116311432944039108215Ozone

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 Massachusetts with a similar median AQI in 2025

All monitored counties in Massachusetts

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