Processed on 2024-03-04 12:54:40 PST.


Disclaimer: Data presented here come from a variety of sources and do not represent official EPA measurements. Please visit AirNow for official measurements.


Cumulative exposure to smoke is an important public health metric. This report summarizes the cumulative number of days air quality monitors in Connecticut spent in each AQI category during the the month of September.

The tables below include only permanent monitors measuring PM2.5 and show cumulative exposure under existing NAAQS (National Ambient Air Quality Standards) and under the 2024 revised standards for PM2.5.

In the tables and plots below, ‘Old’ designates cumulative days calculated using the 2023 PM2.5 NAAQS while ‘New’ is calculated using the 2024 revised PM2.5 NAAQS. The impact of the NAAQS revision is quite clear.

September in Connecticut

September 2014 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 189 22 0 0 0 0 37
New 149 62 0 0 0 0 37

September 2015 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 170 58 0 0 0 0 20
New 134 94 0 0 0 0 20

September 2016 – 16 permanent monitors

Processing error: Unable to calculate tables.

September 2017 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 172 46 0 0 0 0 30
New 126 92 0 0 0 0 30

September 2018 – 16 permanent monitors

Processing error: Unable to calculate tables.

September 2019 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 227 11 0 0 0 0 10
New 209 29 0 0 0 0 10

September 2020 – 16 permanent monitors

Processing error: Unable to calculate tables.

September 2021 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 234 5 0 0 0 0 9
New 222 17 0 0 0 0 9

September 2022 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 238 2 0 0 0 0 8
New 223 17 0 0 0 0 8

September 2023 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 200 39 0 0 0 0 9
New 165 74 0 0 0 0 9