Processed on 2024-03-04 12:56:00 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 May.

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.

May in Delaware

May 2014 – 3 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 68 13 0 0 0 0 15
New 54 27 0 0 0 0 15

May 2015 – 3 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 74 14 0 0 0 0 8
New 56 32 0 0 0 0 8

May 2016 – 6 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 56 6 0 0 0 0 2
New 48 14 0 0 0 0 2

May 2017 – 3 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 84 7 0 0 0 0 5
New 81 10 0 0 0 0 5

May 2018 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 113 9 0 0 0 0 6
New 91 31 0 0 0 0 6

May 2019 – 5 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 152 2 0 0 0 0 6
New 135 19 0 0 0 0 6

May 2020 – 10 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 144 5 0 0 0 0 11
New 132 17 0 0 0 0 11

May 2021 – 5 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 143 5 0 0 0 0 12
New 124 24 0 0 0 0 12

May 2022 – 6 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 167 13 0 0 0 0 12
New 146 34 0 0 0 0 12

May 2023 – 8 permanent monitors

Good Moderate USG Unhealthy Very Unhealthy Hazardous Missing
Old 185 58 0 0 0 0 13
New 151 92 0 0 0 0 13