2021 CEQ Annual Report

Air Quality

Climate Changers Air Pollutants

Air Days

Quick Summary - x check check

Connecticut residents breathed healthful air on 342 days in 2021: an improvement from the 10-year average (340 days).

The number of statewide “good air days” decreased in 2021 from 347 in 2020 to 342 days in 2021 , with three days that exceeded the standard for particulate matter (PM 2.5).⁷ Elevated levels of fine particles (PM2.5) was, in part, due to wildfires, both in the western United States (U.S.) and Canada, that created smoke plumes that impacted Connecticut. During the summer of 2021, the Department of Energy and Environmental Protection (DEEP) was encouraging residents to limit outdoor activities. A “good air day” is when every monitoring station in the state records satisfactory air quality. “Satisfactory air quality” is defined here as air that meets the health-based National Ambient Air Quality Standard (NAAQS) for all of the following six pollutants: sulfur dioxide, carbon monoxide, particulate matter (PM2.5 and PM10), nitrogen dioxide, and ground-level ozone.*

As noted above, Connecticut experienced three days with an Air Quality Index (AQI) above 100 for “fine particles” (such as those found in smoke and haze), which are 2.5 micrometers in diameter or less (PM 2.5). Air with an AQI above 100 is considered “unhealthy for sensitive groups” according to the United States Environmental Protection Agency (EPA)⁸, which includes people with heart or lung disease, older adults, and children. Exposure to particle pollution is linked to a variety of significant health problems, ranging from aggravated asthma to premature death in people with heart and lung disease. Fine particles are a health concern because fine particles can easily reach the deepest parts of the lungs.⁹

The long term trend of improved air quality since 2011 is, in part, due to the air pollution controls that were put in place after the 1971 Clean Air Act. The chart below, “Air Pollutants”, shows that in the 1980’s, exceedances for sulfur dioxide (SO2) and nitrogen dioxide (NO2) were common. Statewide exceedances of pollutants, except for ozone, are rarely seen, due to federal restrictions on emitters, mostly to Connecticut’s west and southwest. Lead (Pb) is not shown.**

Air Pollutants

The image (below) illustrates a bad-air day in 2021 that was more intense than average but followed the typical pattern of Connecticut having the worst ozone Bad air day in New England pollution in New England. 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 and southwest. Unless emissions in those states are reduced substantially, Connecticut residents are likely to 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 saw the most unhealthful days in 2021, included Stratford (13), Westport (12); Madison, Middletown, and Greenwich (11 each); while the air monitoring stations in Abington (Pomfret), Cornwall, Stafford, and East Hartford (1) saw the fewest.¹¹

No other New England state had more days with unhealthful levels of ozone than Connecticut, which had a total of 21 in 2021. Rhode Island was the next highest with five unhealthful days due to ozone.¹²

_Goal:_{While not formally stated, the goal is for Connecticut residents to have a “good air day”, every day.}

_{Technical Note:}_{*The federal air quality standard for ozone was revised prior to the 2016 ozone season. The new standard (0.070 parts per million over eight hours) is slightly more protective of human health than the older standard (0.075). Source of the data represented in the charts is Environmental Protection Agency (EPA) reports that are derived from data received from the Department of Energy and Environmental Protection’s monitors. **Connecticut’s lead levels have been below the national standard (NAAQS) since 1994.}

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⁷_{Environmental Protection Agency (EPA), Air Data: Air Quality Data Collected at Outdoor Monitors Across the US; www.epa.gov/outdoor-air-quality-data}⁸_{EPA, AirNow, Air Quality Index Basics; www.airnow.gov/aqi/aqi-basics/}⁹_{Connecticut Department of Health (DPH); portal.ct.gov/DPH/Environmental-Health/Environmental-and-Occupational-Health-Assessment/Air-Pollution}¹⁰_{EPA, AirNow, Interactive Map of Air Quality, Archive - June 5, 2021; gispub.epa.gov/airnow/index.html?tab=3}¹¹_{DEEP, Annual Summary Information for Ozone; portal.ct.gov/DEEP/Air/Monitoring/Annual-Summary-Information-for-Ozone}¹²_{EPA, Historical Exceedance Days in New England; www3.epa.gov/region1/airquality/standard.html}