The EPA’s National Ambient Air Quality Standards set criteria for the evaluation of pollutants considered potentially harmful to public health and the environment. This includes primary standards, which provide public health protection, and secondary standards, which provide public welfare protection. The standards are available here.1
In April 2016, Bridgeton Landfill and the EPA agreed to the installation and operation of two sulfur dioxide (SO2) ambi­ent air monitors. The monitoring devices were located at a water tower in Spanish Village, which is south of Bridgeton Landfill, and along St. Charles Rock Road, or north of Bridgeton Landfill. The devices collected hourly SO2 measurements and populated the data in real-time online. The data was collected and analyzed for a period of one year in order to provide regulators, local officials and the community with a more accurate characterization of SO2 levels in the area.
According to the EPA, the largest source of SO2 emissions in the atmosphere is the burning of fossil fuels by power plants and other industrial facilities. Smaller sources of SO2 emissions include vehicles and heavy equipment that burn fuel with a high sulfur content.

1EPA’s National Ambient Air Quality Standards