Processed on 2024-03-04 12:55:50 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 Delaware spent in each AQI category during the the month of April.

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.

April in Delaware

April 2014 – 3 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 78 10 0 0 0 0 5
New 65 23 0 0 0 0 5

April 2015 – 3 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 85 1 0 0 0 0 7
New 78 8 0 0 0 0 7

April 2016 – 6 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 54 4 0 0 0 0 35
New 50 8 0 0 0 0 35

April 2017 – 3 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 80 6 0 0 0 0 7
New 73 13 0 0 0 0 7

April 2018 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 111 9 0 0 0 0 4
New 91 29 0 0 0 0 4

April 2019 – 5 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 141 9 0 0 0 0 5
New 134 16 0 0 0 0 5

April 2020 – 10 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 147 2 0 0 0 0 6
New 130 19 0 0 0 0 6

April 2021 – 5 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 139 9 0 0 0 0 7
New 115 33 0 0 0 0 7

April 2022 – 6 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 162 5 0 0 0 0 19
New 146 21 0 0 0 0 19

April 2023 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 223 17 0 0 0 0 8
New 171 69 0 0 0 0 8