EnviroNearby

Hampden County, Massachusetts air quality history

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

77%
Good days in 2025
39
Median daily AQI, 2025
5
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 Hampden, Massachusetts on 365 days. 281 of those days (77%) were in the Good range, and the median daily AQI was 39. 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 221 days. Across the years with fuller monitoring, the share of Good days rose: an average of 59% in 1980–1982 versus 72% 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 163 of 255 days1980: Moderate 63 of 255 days1980: Unhealthy for Sensitive Groups 14 of 255 days1980: Unhealthy 9 of 255 days1980: Very Unhealthy 6 of 255 days19801981: Good 201 of 356 days1981: Moderate 113 of 356 days1981: Unhealthy for Sensitive Groups 30 of 356 days1981: Unhealthy 7 of 356 days1981: Very Unhealthy 5 of 356 days1982: Good 212 of 365 days1982: Moderate 142 of 365 days1982: Unhealthy for Sensitive Groups 4 of 365 days1982: Unhealthy 4 of 365 days1982: Very Unhealthy 3 of 365 days1983: Good 141 of 365 days1983: Moderate 148 of 365 days1983: Unhealthy for Sensitive Groups 36 of 365 days1983: Unhealthy 24 of 365 days1983: Very Unhealthy 16 of 365 days1984: Good 187 of 366 days1984: Moderate 129 of 366 days1984: Unhealthy for Sensitive Groups 34 of 366 days1984: Unhealthy 12 of 366 days1984: Very Unhealthy 4 of 366 days1985: Good 218 of 365 days1985: Moderate 109 of 365 days1985: Unhealthy for Sensitive Groups 17 of 365 days1985: Unhealthy 16 of 365 days1985: Very Unhealthy 5 of 365 days19851986: Good 235 of 365 days1986: Moderate 103 of 365 days1986: Unhealthy for Sensitive Groups 22 of 365 days1986: Unhealthy 4 of 365 days1986: Very Unhealthy 1 of 365 days1987: Good 241 of 365 days1987: Moderate 97 of 365 days1987: Unhealthy for Sensitive Groups 24 of 365 days1987: Unhealthy 3 of 365 days1988: Good 221 of 366 days1988: Moderate 86 of 366 days1988: Unhealthy for Sensitive Groups 36 of 366 days1988: Unhealthy 11 of 366 days1988: Very Unhealthy 12 of 366 days1989: Good 241 of 365 days1989: Moderate 104 of 365 days1989: Unhealthy for Sensitive Groups 13 of 365 days1989: Unhealthy 7 of 365 days1990: Good 252 of 365 days1990: Moderate 93 of 365 days1990: Unhealthy for Sensitive Groups 12 of 365 days1990: Unhealthy 7 of 365 days1990: Very Unhealthy 1 of 365 days19901991: Good 264 of 365 days1991: Moderate 79 of 365 days1991: Unhealthy for Sensitive Groups 15 of 365 days1991: Unhealthy 5 of 365 days1991: Very Unhealthy 2 of 365 days1992: Good 281 of 366 days1992: Moderate 69 of 366 days1992: Unhealthy for Sensitive Groups 10 of 366 days1992: Unhealthy 6 of 366 days1993: Good 244 of 365 days1993: Moderate 88 of 365 days1993: Unhealthy for Sensitive Groups 22 of 365 days1993: Unhealthy 7 of 365 days1993: Very Unhealthy 4 of 365 days1994: Good 194 of 365 days1994: Moderate 138 of 365 days1994: Unhealthy for Sensitive Groups 25 of 365 days1994: Unhealthy 8 of 365 days1995: Good 252 of 365 days1995: Moderate 85 of 365 days1995: Unhealthy for Sensitive Groups 20 of 365 days1995: Unhealthy 7 of 365 days1995: Very Unhealthy 1 of 365 days19951996: Good 279 of 366 days1996: Moderate 72 of 366 days1996: Unhealthy for Sensitive Groups 12 of 366 days1996: Unhealthy 3 of 366 days1997: Good 290 of 365 days1997: Moderate 63 of 365 days1997: Unhealthy for Sensitive Groups 3 of 365 days1997: Unhealthy 9 of 365 days1998: Good 278 of 365 days1998: Moderate 70 of 365 days1998: Unhealthy for Sensitive Groups 12 of 365 days1998: Unhealthy 5 of 365 days1999: Good 171 of 365 days1999: Moderate 169 of 365 days1999: Unhealthy for Sensitive Groups 18 of 365 days1999: Unhealthy 7 of 365 days2000: Good 135 of 366 days2000: Moderate 218 of 366 days2000: Unhealthy for Sensitive Groups 12 of 366 days2000: Unhealthy 1 of 366 days20002001: Good 109 of 365 days2001: Moderate 223 of 365 days2001: Unhealthy for Sensitive Groups 23 of 365 days2001: Unhealthy 10 of 365 days2002: Good 150 of 365 days2002: Moderate 179 of 365 days2002: Unhealthy for Sensitive Groups 25 of 365 days2002: Unhealthy 7 of 365 days2002: Very Unhealthy 4 of 365 days2003: Good 124 of 365 days2003: Moderate 218 of 365 days2003: Unhealthy for Sensitive Groups 20 of 365 days2003: Unhealthy 3 of 365 days2004: Good 128 of 366 days2004: Moderate 226 of 366 days2004: Unhealthy for Sensitive Groups 10 of 366 days2004: Unhealthy 2 of 366 days2005: Good 162 of 365 days2005: Moderate 179 of 365 days2005: Unhealthy for Sensitive Groups 18 of 365 days2005: Unhealthy 6 of 365 days20052006: Good 186 of 365 days2006: Moderate 161 of 365 days2006: Unhealthy for Sensitive Groups 14 of 365 days2006: Unhealthy 3 of 365 days2006: Very Unhealthy 1 of 365 days2007: Good 189 of 365 days2007: Moderate 150 of 365 days2007: Unhealthy for Sensitive Groups 19 of 365 days2007: Unhealthy 5 of 365 days2007: Very Unhealthy 2 of 365 days2008: Good 175 of 366 days2008: Moderate 175 of 366 days2008: Unhealthy for Sensitive Groups 15 of 366 days2008: Unhealthy 1 of 366 days2009: Good 172 of 365 days2009: Moderate 182 of 365 days2009: Unhealthy for Sensitive Groups 11 of 365 days2010: Good 187 of 365 days2010: Moderate 168 of 365 days2010: Unhealthy for Sensitive Groups 9 of 365 days2010: Unhealthy 1 of 365 days20102011: Good 176 of 365 days2011: Moderate 176 of 365 days2011: Unhealthy for Sensitive Groups 11 of 365 days2011: Unhealthy 2 of 365 days2012: Good 179 of 366 days2012: Moderate 176 of 366 days2012: Unhealthy for Sensitive Groups 11 of 366 days2013: Good 224 of 365 days2013: Moderate 135 of 365 days2013: Unhealthy for Sensitive Groups 6 of 365 days2014: Good 213 of 365 days2014: Moderate 152 of 365 days2015: Good 231 of 365 days2015: Moderate 131 of 365 days2015: Unhealthy for Sensitive Groups 3 of 365 days20152016: Good 276 of 366 days2016: Moderate 84 of 366 days2016: Unhealthy for Sensitive Groups 5 of 366 days2016: Unhealthy 1 of 366 days2017: Good 270 of 365 days2017: Moderate 91 of 365 days2017: Unhealthy for Sensitive Groups 4 of 365 days2018: Good 248 of 365 days2018: Moderate 115 of 365 days2018: Unhealthy for Sensitive Groups 2 of 365 days2019: Good 260 of 364 days2019: Moderate 104 of 364 days2020: Good 249 of 366 days2020: Moderate 117 of 366 days20202021: Good 215 of 365 days2021: Moderate 148 of 365 days2021: Unhealthy for Sensitive Groups 2 of 365 days2022: Good 262 of 365 days2022: Moderate 102 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days2023: Good 220 of 365 days2023: Moderate 139 of 365 days2023: Unhealthy for Sensitive Groups 4 of 365 days2023: Unhealthy 2 of 365 days2024: Good 290 of 366 days2024: Moderate 74 of 366 days2024: Unhealthy for Sensitive Groups 2 of 366 days2025: Good 281 of 365 days2025: Moderate 79 of 365 days2025: Unhealthy for Sensitive Groups 5 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 year0501001502001980: 90th percentile AQI 1081981: 90th percentile AQI 1041982: 90th percentile AQI 761983: 90th percentile AQI 1561984: 90th percentile AQI 1121985: 90th percentile AQI 1051986: 90th percentile AQI 871987: 90th percentile AQI 871988: 90th percentile AQI 1151989: 90th percentile AQI 801990: 90th percentile AQI 841991: 90th percentile AQI 771992: 90th percentile AQI 651993: 90th percentile AQI 1001994: 90th percentile AQI 1001995: 90th percentile AQI 901996: 90th percentile AQI 741997: 90th percentile AQI 651998: 90th percentile AQI 711999: 90th percentile AQI 872000: 90th percentile AQI 842001: 90th percentile AQI 952002: 90th percentile AQI 992003: 90th percentile AQI 872004: 90th percentile AQI 832005: 90th percentile AQI 902006: 90th percentile AQI 872007: 90th percentile AQI 872008: 90th percentile AQI 802009: 90th percentile AQI 772010: 90th percentile AQI 742011: 90th percentile AQI 802012: 90th percentile AQI 742013: 90th percentile AQI 682014: 90th percentile AQI 662015: 90th percentile AQI 672016: 90th percentile AQI 622017: 90th percentile AQI 612018: 90th percentile AQI 622019: 90th percentile AQI 582020: 90th percentile AQI 602021: 90th percentile AQI 632022: 90th percentile AQI 612023: 90th percentile AQI 622024: 90th percentile AQI 582025: 90th percentile AQI 611980: Median AQI 431981: Median AQI 471982: Median AQI 471983: Median AQI 591984: Median AQI 501985: Median AQI 471986: Median AQI 451987: Median AQI 451988: Median AQI 451989: Median AQI 441990: Median AQI 441991: Median AQI 431992: Median AQI 411993: Median AQI 441994: Median AQI 491995: Median AQI 431996: Median AQI 421997: Median AQI 401998: Median AQI 391999: Median AQI 512000: Median AQI 562001: Median AQI 582002: Median AQI 562003: Median AQI 552004: Median AQI 552005: Median AQI 542006: Median AQI 492007: Median AQI 482008: Median AQI 512009: Median AQI 522010: Median AQI 492011: Median AQI 522012: Median AQI 512013: Median AQI 452014: Median AQI 462015: Median AQI 432016: Median AQI 412017: Median AQI 422018: Median AQI 412019: Median AQI 432020: Median AQI 442021: Median AQI 462022: Median AQI 422023: Median AQI 462024: Median AQI 372025: 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
Ozone22161%
Fine particles (PM2.5)13637%
Nitrogen dioxide (NO₂)82%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652817950003961124Ozone
20243662907420003758119Ozone
202336522013942004662153PM2.5
202236526210210004261115PM2.5
202136521514820004663116PM2.5
20203662491170000446099PM2.5
20193642601040000435893PM2.5
201836524811520004162126Ozone
20173652709140004261112Ozone
20163662768451004162161Ozone
201536523113130004367147PM2.5
201436521315200004666100PM2.5
201336522413560004568140PM2.5
2012366179176110005174147PM2.5
2011365176176112005280162PM2.5
201036518716891004974164PM2.5
2009365172182110005277133PM2.5
2008366175175151005180151PM2.5
2007365189150195204887207PM2.5
2006365186161143104987215PM2.5
2005365162179186005490197PM2.5
2004366128226102005583169PM2.5
2003365124218203005587185PM2.5
2002365150179257405699214PM2.5
20013651092232310005895200PM2.5
2000366135218121005684161PM2.5
1999365171169187005187174PM2.5
199836527870125003971197Ozone
19973652906339004065197Ozone
199636627972123004274172NO2
199536525285207104390204Ozone
19943651941382580049100195NO2
1993365244882274044100216Ozone
199236628169106004165200NO2
199136526479155204377208NO2
199036525293127104484201NO2
1989365241104137004480195Ozone
198836622186361112045115240NO2
198736524197243004587195NO2
1986365235103224104587208CO
198536521810917165047105242Ozone
198436618712934124050112219Ozone
1983365141148362416059156253CO
198236521214244304776219CO
19813562011133075047104219Ozone
1980255163631496043108236CO

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