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March 25, 2024

Report: CT’s air quality deteriorated in 2023. Which town had the most pollution?

By Andrew Larson

Connecticut’s air quality deteriorated in 2023, but most of its towns and cities still fell into the “good” category, which means pollution levels only exceed World Health Organization (WHO) guidelines by one or two times.

According to IQAir, which ranked more than 7,800 locations worldwide based on data collected from thousands of air quality monitoring stations, Trumbull had the worst air quality in Connecticut. Its 2023 average PM2.5 concentration was 12.1 μg/m³, up from 9.9 μg/m³ in 2022.

WHO’s annual PM2.5 guideline for healthy air is 5 µg/m³ or less.

Oxford had the second-worst air quality in Connecticut in 2023, with an average PM2.5 concentration of 11.6 μg/m³, up from 11 μg/m³ in 2022.

Both Trumbull and Oxford were in the yellow category, which means the air quality was considered “moderate.”

The state’s largest city, Bridgeport, had the third-highest pollution level with an average of 9.9 μg/m³ in 2023, up from 8.4 μg/m³ in 2022. 

IQAir’s study considered pollution levels below 10 μg/m³ “good” even though they exceeded WHO guidelines.

Hartford ranked ninth, with an average of 9.4 μg/m³ in 2023, up from 8.5 μg/m³ in 2022.

The least polluted town was Colebrook, with an average of 6.4 μg/m³ in 2023, up from 5.5 μg/m³ in 2022.

In June, many towns fell into the orange category, which means “unhealthy for sensitive groups.” The highest monthly average pollutant levels were 23.7 μg/m³ in Bridgeport and East Haven – levels that are considered unhealthy for all people.

The highest levels were recorded during the Canadian wildfires, which brought heavy smoke into Connecticut.

The most polluted city in the United States was Coraopolis, Pennsylvania, which had an average PM2.5 concentration of 19.3 μg/m³ in 2023.

The least-polluted town in the United States was Wilson, Wyoming, where the average 2023 pollution level was 1.9 μg/m³, which meets WHO guidelines.

Other parts of the world had much worse pollution, including Bangladesh, where the air was generally considered “unhealthy” in 2023, and in the African country of Chad, where air quality was considered “unhealthy” to “very unhealthy.”

Overall, the United States had the 102nd worst air quality of all countries in the world in 2023. Thirty-two counties scored higher than the United States, putting it in the 74th percentile.

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