EnviroNearby

New Haven County, Connecticut air quality history

Daily Air Quality Index summaries from EPA monitors in New Haven, Connecticut, 1980–2025.

67%
Good days in 2025
43
Median daily AQI, 2025
13
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 New Haven, Connecticut on 365 days. 245 of those days (67%) were in the Good range, and the median daily AQI was 43. That median is about the same as the typical monitored county in Connecticut (median 41 across 8 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 226 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 1980–1982 versus 65% 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 192 of 297 days1980: Moderate 57 of 297 days1980: Unhealthy for Sensitive Groups 13 of 297 days1980: Unhealthy 16 of 297 days1980: Very Unhealthy 19 of 297 days19801981: Good 245 of 365 days1981: Moderate 71 of 365 days1981: Unhealthy for Sensitive Groups 20 of 365 days1981: Unhealthy 21 of 365 days1981: Very Unhealthy 8 of 365 days1982: Good 196 of 365 days1982: Moderate 119 of 365 days1982: Unhealthy for Sensitive Groups 29 of 365 days1982: Unhealthy 10 of 365 days1982: Very Unhealthy 11 of 365 days1983: Good 185 of 365 days1983: Moderate 107 of 365 days1983: Unhealthy for Sensitive Groups 31 of 365 days1983: Unhealthy 16 of 365 days1983: Very Unhealthy 26 of 365 days1984: Good 192 of 359 days1984: Moderate 115 of 359 days1984: Unhealthy for Sensitive Groups 25 of 359 days1984: Unhealthy 16 of 359 days1984: Very Unhealthy 11 of 359 days1985: Good 189 of 365 days1985: Moderate 143 of 365 days1985: Unhealthy for Sensitive Groups 16 of 365 days1985: Unhealthy 13 of 365 days1985: Very Unhealthy 4 of 365 days19851986: Good 183 of 365 days1986: Moderate 157 of 365 days1986: Unhealthy for Sensitive Groups 15 of 365 days1986: Unhealthy 7 of 365 days1986: Very Unhealthy 3 of 365 days1987: Good 189 of 365 days1987: Moderate 136 of 365 days1987: Unhealthy for Sensitive Groups 18 of 365 days1987: Unhealthy 13 of 365 days1987: Very Unhealthy 9 of 365 days1988: Good 203 of 366 days1988: Moderate 120 of 366 days1988: Unhealthy for Sensitive Groups 19 of 366 days1988: Unhealthy 16 of 366 days1988: Very Unhealthy 8 of 366 days1989: Good 202 of 365 days1989: Moderate 137 of 365 days1989: Unhealthy for Sensitive Groups 15 of 365 days1989: Unhealthy 7 of 365 days1989: Very Unhealthy 4 of 365 days1990: Good 202 of 365 days1990: Moderate 123 of 365 days1990: Unhealthy for Sensitive Groups 25 of 365 days1990: Unhealthy 10 of 365 days1990: Very Unhealthy 5 of 365 days19901991: Good 166 of 365 days1991: Moderate 156 of 365 days1991: Unhealthy for Sensitive Groups 16 of 365 days1991: Unhealthy 17 of 365 days1991: Very Unhealthy 10 of 365 days1992: Good 229 of 366 days1992: Moderate 117 of 366 days1992: Unhealthy for Sensitive Groups 11 of 366 days1992: Unhealthy 9 of 366 days1993: Good 160 of 365 days1993: Moderate 175 of 365 days1993: Unhealthy for Sensitive Groups 17 of 365 days1993: Unhealthy 11 of 365 days1993: Very Unhealthy 2 of 365 days1994: Good 185 of 365 days1994: Moderate 146 of 365 days1994: Unhealthy for Sensitive Groups 21 of 365 days1994: Unhealthy 11 of 365 days1994: Very Unhealthy 2 of 365 days1995: Good 260 of 365 days1995: Moderate 79 of 365 days1995: Unhealthy for Sensitive Groups 14 of 365 days1995: Unhealthy 6 of 365 days1995: Very Unhealthy 6 of 365 days19951996: Good 268 of 366 days1996: Moderate 77 of 366 days1996: Unhealthy for Sensitive Groups 13 of 366 days1996: Unhealthy 7 of 366 days1996: Very Unhealthy 1 of 366 days1997: Good 266 of 365 days1997: Moderate 70 of 365 days1997: Unhealthy for Sensitive Groups 12 of 365 days1997: Unhealthy 11 of 365 days1997: Very Unhealthy 6 of 365 days1998: Good 233 of 365 days1998: Moderate 106 of 365 days1998: Unhealthy for Sensitive Groups 18 of 365 days1998: Unhealthy 7 of 365 days1998: Very Unhealthy 1 of 365 days1999: Good 179 of 365 days1999: Moderate 150 of 365 days1999: Unhealthy for Sensitive Groups 20 of 365 days1999: Unhealthy 11 of 365 days1999: Very Unhealthy 5 of 365 days2000: Good 96 of 366 days2000: Moderate 243 of 366 days2000: Unhealthy for Sensitive Groups 21 of 366 days2000: Unhealthy 5 of 366 days2000: Very Unhealthy 1 of 366 days20002001: Good 68 of 365 days2001: Moderate 260 of 365 days2001: Unhealthy for Sensitive Groups 23 of 365 days2001: Unhealthy 12 of 365 days2001: Very Unhealthy 2 of 365 days2002: Good 89 of 365 days2002: Moderate 228 of 365 days2002: Unhealthy for Sensitive Groups 23 of 365 days2002: Unhealthy 19 of 365 days2002: Very Unhealthy 6 of 365 days2003: Good 75 of 365 days2003: Moderate 255 of 365 days2003: Unhealthy for Sensitive Groups 26 of 365 days2003: Unhealthy 6 of 365 days2003: Very Unhealthy 3 of 365 days2004: Good 62 of 366 days2004: Moderate 289 of 366 days2004: Unhealthy for Sensitive Groups 13 of 366 days2004: Unhealthy 1 of 366 days2004: Very Unhealthy 1 of 366 days2005: Good 131 of 365 days2005: Moderate 200 of 365 days2005: Unhealthy for Sensitive Groups 26 of 365 days2005: Unhealthy 7 of 365 days2005: Very Unhealthy 1 of 365 days20052006: Good 154 of 365 days2006: Moderate 189 of 365 days2006: Unhealthy for Sensitive Groups 17 of 365 days2006: Unhealthy 4 of 365 days2006: Very Unhealthy 1 of 365 days2007: Good 166 of 365 days2007: Moderate 170 of 365 days2007: Unhealthy for Sensitive Groups 22 of 365 days2007: Unhealthy 7 of 365 days2008: Good 153 of 366 days2008: Moderate 195 of 366 days2008: Unhealthy for Sensitive Groups 16 of 366 days2008: Unhealthy 2 of 366 days2009: Good 200 of 365 days2009: Moderate 160 of 365 days2009: Unhealthy for Sensitive Groups 5 of 365 days2010: Good 204 of 364 days2010: Moderate 143 of 364 days2010: Unhealthy for Sensitive Groups 17 of 364 days20102011: Good 181 of 365 days2011: Moderate 170 of 365 days2011: Unhealthy for Sensitive Groups 8 of 365 days2011: Unhealthy 6 of 365 days2012: Good 120 of 366 days2012: Moderate 220 of 366 days2012: Unhealthy for Sensitive Groups 19 of 366 days2012: Unhealthy 7 of 366 days2013: Good 106 of 365 days2013: Moderate 244 of 365 days2013: Unhealthy for Sensitive Groups 12 of 365 days2013: Unhealthy 3 of 365 days2014: Good 174 of 365 days2014: Moderate 183 of 365 days2014: Unhealthy for Sensitive Groups 8 of 365 days2015: Good 161 of 365 days2015: Moderate 188 of 365 days2015: Unhealthy for Sensitive Groups 13 of 365 days2015: Unhealthy 3 of 365 days20152016: Good 211 of 366 days2016: Moderate 141 of 366 days2016: Unhealthy for Sensitive Groups 11 of 366 days2016: Unhealthy 3 of 366 days2017: Good 241 of 365 days2017: Moderate 112 of 365 days2017: Unhealthy for Sensitive Groups 8 of 365 days2017: Unhealthy 4 of 365 days2018: Good 220 of 365 days2018: Moderate 131 of 365 days2018: Unhealthy for Sensitive Groups 12 of 365 days2018: Unhealthy 2 of 365 days2019: Good 228 of 365 days2019: Moderate 123 of 365 days2019: Unhealthy for Sensitive Groups 12 of 365 days2019: Unhealthy 2 of 365 days2020: Good 210 of 366 days2020: Moderate 143 of 366 days2020: Unhealthy for Sensitive Groups 11 of 366 days2020: Unhealthy 2 of 366 days20202021: Good 220 of 365 days2021: Moderate 131 of 365 days2021: Unhealthy for Sensitive Groups 12 of 365 days2021: Unhealthy 2 of 365 days2022: Good 230 of 365 days2022: Moderate 128 of 365 days2022: Unhealthy for Sensitive Groups 7 of 365 days2023: Good 205 of 365 days2023: Moderate 148 of 365 days2023: Unhealthy for Sensitive Groups 9 of 365 days2023: Unhealthy 2 of 365 days2023: Very Unhealthy 1 of 365 days2024: Good 260 of 366 days2024: Moderate 94 of 366 days2024: Unhealthy for Sensitive Groups 11 of 366 days2024: Unhealthy 1 of 366 days2025: Good 245 of 365 days2025: Moderate 107 of 365 days2025: Unhealthy for Sensitive Groups 11 of 365 days2025: Unhealthy 2 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 1561981: 90th percentile AQI 1221982: 90th percentile AQI 1151983: 90th percentile AQI 1691984: 90th percentile AQI 1331985: 90th percentile AQI 1001986: 90th percentile AQI 901987: 90th percentile AQI 1011988: 90th percentile AQI 1221989: 90th percentile AQI 841990: 90th percentile AQI 1011991: 90th percentile AQI 1161992: 90th percentile AQI 841993: 90th percentile AQI 971994: 90th percentile AQI 1001995: 90th percentile AQI 841996: 90th percentile AQI 761997: 90th percentile AQI 901998: 90th percentile AQI 871999: 90th percentile AQI 1002000: 90th percentile AQI 932001: 90th percentile AQI 1012002: 90th percentile AQI 1262003: 90th percentile AQI 1002004: 90th percentile AQI 872005: 90th percentile AQI 1002006: 90th percentile AQI 852007: 90th percentile AQI 902008: 90th percentile AQI 862009: 90th percentile AQI 742010: 90th percentile AQI 782011: 90th percentile AQI 792012: 90th percentile AQI 812013: 90th percentile AQI 822014: 90th percentile AQI 762015: 90th percentile AQI 772016: 90th percentile AQI 742017: 90th percentile AQI 642018: 90th percentile AQI 712019: 90th percentile AQI 702020: 90th percentile AQI 772021: 90th percentile AQI 692022: 90th percentile AQI 692023: 90th percentile AQI 742024: 90th percentile AQI 622025: 90th percentile AQI 681980: Median AQI 381981: Median AQI 421982: Median AQI 481983: Median AQI 501984: Median AQI 471985: Median AQI 491986: Median AQI 501987: Median AQI 501988: Median AQI 491989: Median AQI 481990: Median AQI 481991: Median AQI 521992: Median AQI 451993: Median AQI 531994: Median AQI 501995: Median AQI 431996: Median AQI 431997: Median AQI 421998: Median AQI 441999: Median AQI 512000: Median AQI 592001: Median AQI 642002: Median AQI 602003: Median AQI 632004: Median AQI 602005: Median AQI 562006: Median AQI 532007: Median AQI 522008: Median AQI 532009: Median AQI 472010: Median AQI 462011: Median AQI 512012: Median AQI 542013: Median AQI 562014: Median AQI 512015: Median AQI 522016: Median AQI 472017: Median AQI 442018: Median AQI 442019: Median AQI 442020: Median AQI 462021: Median AQI 462022: Median AQI 442023: Median AQI 472024: Median AQI 412025: Median AQI 431980198519901995200020052010201520202025
  • 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
Ozone22662%
Fine particles (PM2.5)12534%
Nitrogen dioxide (NO₂)144%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025365245107112004368159Ozone
202436626094111004162156Ozone
202336520514892104774208PM2.5
202236523012870004469133PM2.5
2021365220131122004669159PM2.5
2020366210143112004677174PM2.5
2019365228123122004470159Ozone
2018365220131122004471156PM2.5
201736524111284004464179Ozone
2016366211141113004774164Ozone
2015365161188133005277169PM2.5
201436517418380005176126PM2.5
2013365106244123005682159PM2.5
2012366120220197005481187PM2.5
201136518117086005179195PM2.5
2010364204143170004678140PM2.5
200936520016050004774129PM2.5
2008366153195162005386200PM2.5
2007365166170227005290200PM2.5
2006365154189174105385209PM2.5
20053651312002671056100203PM2.5
200436662289131106087206PM2.5
2003365752552663063100220PM2.5
20023658922823196060126230PM2.5
20013656826023122064101229PM2.5
200036696243215105993217PM2.5
199936517915020115051100226NO2
1998365233106187104487202NO2
1997365266701211604290248NO2
199636626877137104376202NO2
199536526079146604384238NO2
199436518514621112050100219NO2
19933651601751711205397207PM10
1992366229117119004584195NO2
1991365166156161710052116248Ozone
199036520212325105048101246NO2
1989365202137157404884225NO2
198836620312019168049122241NO2
198736518913618139050101226NO2
1986365183157157305090228NO2
198536518914316134049100227NO2
1984359192115251611047133248NO2
1983365185107311626050169273NO2
1982365196119291011048115242NO2
19813652457120218042122230Ozone
198029719257131619038156295Ozone

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 Connecticut with a similar median AQI in 2025

All monitored counties in Connecticut

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