EnviroNearby

Berkshire County, Massachusetts air quality history

Daily Air Quality Index summaries from EPA monitors in Berkshire, Massachusetts, 1980–2025.

78%
Good days in 2025
38
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 Berkshire, Massachusetts on 365 days. 285 of those days (78%) were in the Good range, and the median daily AQI was 38. That median is about the same as the typical monitored county in Massachusetts (median 38 across 13 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 230 days. Across the years with fuller monitoring, the share of Good days rose: an average of 71% in 1980–1983 versus 77% in 2023–2025.

Years with fewer than 120 monitored days (1981) are shown in the table but left out of comparisons and trend statements.

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 151 of 204 days1980: Moderate 26 of 204 days1980: Unhealthy for Sensitive Groups 19 of 204 days1980: Unhealthy 7 of 204 days1980: Very Unhealthy 1 of 204 days19801981: Good 86 of 103 days1981: Moderate 13 of 103 days1981: Unhealthy for Sensitive Groups 1 of 103 days1981: Unhealthy 3 of 103 days1982: Good 87 of 122 days1982: Moderate 21 of 122 days1982: Unhealthy for Sensitive Groups 10 of 122 days1982: Unhealthy 4 of 122 days1983: Good 98 of 145 days1983: Moderate 21 of 145 days1983: Unhealthy for Sensitive Groups 21 of 145 days1983: Unhealthy 4 of 145 days1983: Very Unhealthy 1 of 145 days1984: Good 147 of 194 days1984: Moderate 31 of 194 days1984: Unhealthy for Sensitive Groups 8 of 194 days1984: Unhealthy 7 of 194 days1984: Very Unhealthy 1 of 194 days1985: Good 169 of 214 days1985: Moderate 37 of 214 days1985: Unhealthy for Sensitive Groups 4 of 214 days1985: Unhealthy 4 of 214 days19851989: Good 132 of 164 days1989: Moderate 25 of 164 days1989: Unhealthy for Sensitive Groups 7 of 164 days1990: Good 89 of 144 days1990: Moderate 38 of 144 days1990: Unhealthy for Sensitive Groups 12 of 144 days1990: Unhealthy 4 of 144 days1990: Very Unhealthy 1 of 144 days1991: Good 114 of 188 days1991: Moderate 48 of 188 days1991: Unhealthy for Sensitive Groups 17 of 188 days1991: Unhealthy 9 of 188 days1992: Good 117 of 152 days1992: Moderate 22 of 152 days1992: Unhealthy for Sensitive Groups 9 of 152 days1992: Unhealthy 3 of 152 days1992: Very Unhealthy 1 of 152 days1993: Good 113 of 155 days1993: Moderate 31 of 155 days1993: Unhealthy for Sensitive Groups 8 of 155 days1993: Unhealthy 3 of 155 days19931994: Good 109 of 155 days1994: Moderate 37 of 155 days1994: Unhealthy for Sensitive Groups 9 of 155 days1995: Good 141 of 171 days1995: Moderate 25 of 171 days1995: Unhealthy for Sensitive Groups 5 of 171 days1996: Good 102 of 147 days1996: Moderate 37 of 147 days1996: Unhealthy for Sensitive Groups 7 of 147 days1996: Unhealthy 1 of 147 days1997: Good 88 of 122 days1997: Moderate 22 of 122 days1997: Unhealthy for Sensitive Groups 11 of 122 days1997: Unhealthy 1 of 122 days1998: Good 131 of 162 days1998: Moderate 27 of 162 days1998: Unhealthy for Sensitive Groups 4 of 162 days19981999: Good 132 of 208 days1999: Moderate 65 of 208 days1999: Unhealthy for Sensitive Groups 9 of 208 days1999: Unhealthy 2 of 208 days2000: Good 121 of 193 days2000: Moderate 66 of 193 days2000: Unhealthy for Sensitive Groups 5 of 193 days2000: Unhealthy 1 of 193 days2001: Good 89 of 198 days2001: Moderate 78 of 198 days2001: Unhealthy for Sensitive Groups 16 of 198 days2001: Unhealthy 14 of 198 days2001: Very Unhealthy 1 of 198 days2002: Good 127 of 208 days2002: Moderate 60 of 208 days2002: Unhealthy for Sensitive Groups 16 of 208 days2002: Unhealthy 5 of 208 days2003: Good 107 of 201 days2003: Moderate 80 of 201 days2003: Unhealthy for Sensitive Groups 12 of 201 days2003: Unhealthy 2 of 201 days20032004: Good 133 of 217 days2004: Moderate 79 of 217 days2004: Unhealthy for Sensitive Groups 4 of 217 days2004: Unhealthy 1 of 217 days2005: Good 117 of 230 days2005: Moderate 90 of 230 days2005: Unhealthy for Sensitive Groups 18 of 230 days2005: Unhealthy 5 of 230 days2006: Good 196 of 365 days2006: Moderate 161 of 365 days2006: Unhealthy for Sensitive Groups 8 of 365 days2007: Good 217 of 363 days2007: Moderate 122 of 363 days2007: Unhealthy for Sensitive Groups 22 of 363 days2007: Unhealthy 2 of 363 days2008: Good 205 of 366 days2008: Moderate 155 of 366 days2008: Unhealthy for Sensitive Groups 4 of 366 days2008: Unhealthy 2 of 366 days20082009: Good 180 of 352 days2009: Moderate 169 of 352 days2009: Unhealthy for Sensitive Groups 3 of 352 days2010: Good 224 of 348 days2010: Moderate 116 of 348 days2010: Unhealthy for Sensitive Groups 8 of 348 days2011: Good 165 of 363 days2011: Moderate 194 of 363 days2011: Unhealthy for Sensitive Groups 3 of 363 days2011: Unhealthy 1 of 363 days2012: Good 166 of 348 days2012: Moderate 175 of 348 days2012: Unhealthy for Sensitive Groups 7 of 348 days2013: Good 129 of 364 days2013: Moderate 231 of 364 days2013: Unhealthy for Sensitive Groups 4 of 364 days20132014: Good 164 of 364 days2014: Moderate 200 of 364 days2015: Good 215 of 360 days2015: Moderate 145 of 360 days2016: Good 259 of 355 days2016: Moderate 96 of 355 days2017: Good 203 of 346 days2017: Moderate 143 of 346 days2018: Good 232 of 365 days2018: Moderate 132 of 365 days2018: Unhealthy for Sensitive Groups 1 of 365 days20182019: Good 266 of 364 days2019: Moderate 98 of 364 days2020: Good 278 of 366 days2020: Moderate 88 of 366 days2021: Good 230 of 365 days2021: Moderate 134 of 365 days2021: Unhealthy for Sensitive Groups 1 of 365 days2022: Good 269 of 365 days2022: Moderate 96 of 365 days2023: Good 257 of 365 days2023: Moderate 101 of 365 days2023: Unhealthy for Sensitive Groups 4 of 365 days2023: Unhealthy 3 of 365 days20232024: Good 300 of 366 days2024: Moderate 66 of 366 days2025: Good 285 of 365 days2025: Moderate 76 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 year0501001501980: 90th percentile AQI 1121981: 90th percentile AQI 641982: 90th percentile AQI 1121983: 90th percentile AQI 1191984: 90th percentile AQI 971985: 90th percentile AQI 801989: 90th percentile AQI 741990: 90th percentile AQI 1081991: 90th percentile AQI 1121992: 90th percentile AQI 971993: 90th percentile AQI 801994: 90th percentile AQI 841995: 90th percentile AQI 641996: 90th percentile AQI 841997: 90th percentile AQI 901998: 90th percentile AQI 671999: 90th percentile AQI 802000: 90th percentile AQI 752001: 90th percentile AQI 1332002: 90th percentile AQI 1012003: 90th percentile AQI 932004: 90th percentile AQI 772005: 90th percentile AQI 1012006: 90th percentile AQI 792007: 90th percentile AQI 872008: 90th percentile AQI 762009: 90th percentile AQI 742010: 90th percentile AQI 712011: 90th percentile AQI 752012: 90th percentile AQI 752013: 90th percentile AQI 712014: 90th percentile AQI 672015: 90th percentile AQI 612016: 90th percentile AQI 582017: 90th percentile AQI 592018: 90th percentile AQI 632019: 90th percentile AQI 572020: 90th percentile AQI 572021: 90th percentile AQI 602022: 90th percentile AQI 582023: 90th percentile AQI 592024: 90th percentile AQI 562025: 90th percentile AQI 591980: Median AQI 421981: Median AQI 341982: Median AQI 441983: Median AQI 441984: Median AQI 391985: Median AQI 381989: Median AQI 431990: Median AQI 461991: Median AQI 451992: Median AQI 391993: Median AQI 411994: Median AQI 431995: Median AQI 361996: Median AQI 421997: Median AQI 411998: Median AQI 381999: Median AQI 452000: Median AQI 442001: Median AQI 542002: Median AQI 432003: Median AQI 492004: Median AQI 462005: Median AQI 502006: Median AQI 482007: Median AQI 442008: Median AQI 472009: Median AQI 492010: Median AQI 412011: Median AQI 522012: Median AQI 512013: Median AQI 532014: Median AQI 522015: Median AQI 452016: Median AQI 362017: Median AQI 472018: Median AQI 422019: Median AQI 412020: Median AQI 402021: Median AQI 442022: Median AQI 422023: Median AQI 412024: Median AQI 382025: Median AQI 381980198519931998200320082013201820232025
  • 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
Ozone23063%
Fine particles (PM2.5)12935%
Nitrogen dioxide (NO₂)62%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652857640003859124Ozone
2024366300660000385697Ozone
202336525710143004159170PM2.5
2022365269960000425887PM2.5
202136523013410004460103PM2.5
2020366278880000405794PM2.5
2019364266980000415787PM2.5
201836523213210004263122PM2.5
20173462031430000475988PM2.5
2016355259960000365882PM2.5
20153602151450000456195PM2.5
20143641642000000526793PM2.5
201336412923140005371119PM2.5
201234816617570005175112PM2.5
201136316519431005275156PM2.5
201034822411680004171133PM2.5
200935218016930004974143PM2.5
200836620515542004776187PM2.5
2007363217122222004487169PM2.5
200636519616180004879140PM2.5
2005230117901850050101164Ozone
20042171337941004677151Ozone
200320110780122004993197Ozone
2002208127601650043101190Ozone
2001198897816141054133203Ozone
20001931216651004475161Ozone
19992081326592004580158Ozone
19981621312740003867119Ozone
19971228822111004190161Ozone
19961471023771004284177Ozone
19951711412550003664143Ozone
19941551093790004384129Ozone
19931551133183004180192Ozone
19921521172293103997222Ozone
1991188114481790045112177Ozone
199014489381241046108203Ozone
19891641322570004374150Ozone
19852141693744003880172Ozone
19841941473187103997201Ozone
198314598212141044119225Ozone
198212287211040044112185Ozone
1981103861313003464185Ozone
1980204151261971042112204Ozone

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 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