The Division of Air Quality operates a series of monitoring stations throughout the State and deploys a Movable Monitoring Platform for deployment in selected areas. This monitoring network measures pollutants for which national air quality standards have been defined to protect public health. These are known as “Criteria Air Pollutants.”
The standards that the Delaware network measures for are set as part of the National Ambient Air Quality Standards (NAAQS). They include an adequate margin of safety to protect sensitive populations such as children and asthmatics. The criteria air pollutants monitored are Ozone (O3), Carbon Monoxide (CO), Nitrogen Dioxide (NO2), Sulfur Dioxide (SO2), Lead (Pb), and Particulate Matter, both fine particles (PM2.5) and coarse particles (PM10).
The Delaware air quality monitoring network includes permanent monitoring stations in all three counties and one mobile monitoring station used for special studies. Eight of the permanent monitoring stations measure multiple pollutants. Three measure only particulate matter.
The data collected from these monitoring stations is stored in a central DNREC data system and reported to the EPA’s Air Now website and the EPA’s National Air Quality Database. The raw data are posted as part of the Delaware Open Data Portal. They are presented in real time on the DNREC Air Monitoring application. And they are used in special studies by DNREC undertaken to address concerns of citizens.
Monitoring stations are placed in locations based on factors that include population data, meteorological conditions, locations of pollution-emitting industry, and historical air quality trends. The state performs periodic assessments of its network every five years to determine if the network meets the state’s monitoring objectives. The most recent review was completed in 2015. Every year the state submits to EPA for approval an annual monitoring plan which includes the results of the most recent five-year assessment, describes the network and any changes planned. The most recent approved plan is the 2020 Delaware Air Monitoring Network Description.
The Annual Air Quality Reports serve as a resource for information on Air Quality issues in Delaware. The reports focus on Delaware’s air quality status and trends for pollutants shown to threaten human health and welfare for which standards have been set by the EPA, known as the “criteria pollutants.” Information is also provided on some pollutants monitored without standard criteria, such as air toxics.
In additional to air monitoring the reports include discussions on sources of air pollution, inventory data related to the compounds responsible for forming ozone and PM2.5 pollution, and air quality issues related to climate change.