Connecticut residents breathed healthful air on 347 days in 2020: an improvement of ten days from the 10-year average (337).
The number of statewide “good air days” increased in 2020 from 343 days in 2019 to 347 in 2020, with two days that exceeded the standard for particulate matter (PM 2.5).4 The number of good air days has increased by approximately 2.7 percent since 2011.
The image (right) illustrates a typical bad-air day in 2020 that was more intense than average but followed the typical pattern of Connecticut having the worst ozone pollution in New England.5 The yellow areas indicate moderate air quality, but it meets the standard for ground-level ozone, while the orange and red areas did not. Some residents in the yellow areas, who are unusually sensitive to pollution, might have been affected. Much of Connecticut's ground-level ozone originates in states to the west. Unless emissions in those states are reduced substantially, Connecticut residents could continue to breathe unhealthful air.
Cities and towns in coastal regions of the state usually see more bad ozone days than inland locations. Coastal towns with monitoring stations that saw the most unhealthful days in 2020, included Madison (12); Stratford (8); Westport and Greenwich (6 each); while the air monitoring stations in Abington (Pomfret), Cornwall, Stafford, and East Hartford (0) saw the fewest.6
No other New England state had more days with unhealthful levels of ozone than Connecticut, which had a total of 17 in 2020. Rhode Island was the next highest with four unhealthful days.7
4 Environmental Protection Agency (EPA), Air Data: Air Quality Data Collected at Outdoor Monitors Across the US; www.epa.gov/outdoor-air-quality-data
5 EPA, AirNow, Interactive Map of Air Quality; gispub.epa.gov/airnow/index.html?tab=3
6DEEP, Annual Summary Information for Ozone; portal.ct.gov/DEEP/Air/Monitoring/Annual-Summary-Information-for-Ozone
7EPA, Historical Exceedance Days in New England www3.epa.gov/region1/airquality/standard.html