From 1994 to 1999, the Connecticut Department of Environmental Protection tested the emissions of Connecticut’s municipal waste combustors, including CRRA’s four trash-to-energy plants, for metal pollutants and for dioxin/furans. They compared the results of these tests to a health-based standard, the Maximum Allowable Stack Concentration, or MASC.
The MASC was derived from the federal Occupational Safety and Health Administration’s workplace exposure safety standards. The MASC was a means to calculate the exposure to a given pollutant that a person standing at the fenceline of a facility would experience. In other words, the MASC is the amount of a particular substance to which a next-door neighbor would be exposed.
The results of the Connecticut DEP emissions testing at CRRA’s trash-to-energy facilities were always very favorable compared to the MASC – typically, measured values were 1 percent or less of the MASC for each of the metals and for dioxin/furans. In the absence of other standards, the MASC served the purpose of providing a “health-based” emission concentration limit for pollutants.
The federal Clean Air Act took a more systematic, rigorous look at setting emissions standards, based not on emission levels that may cause health effects, but on the technology that is available, industry by industry, for the greatest level of control of emissions. The U.S. Environmental Protection Agency has surveyed many industries and determined the Maximum Available Control Technology (MACT) for each. USEPA set emission limits based on the top-performing facilities. These “technology-based” emission standards are far stricter than the “health-based” standards of the MASC.
For instance, the “health-based” MASC for mercury emissions at CRRA’s four trash-to-energy plants was typically 0.519 to 3.536 mg/dscm compared to the “technology-based” MACT of 0.028 mg/dscm.
CRRA’s trash-to-energy facilities undergo rigorous emissions testing by independent third-party scientists, and DEP reviews and certifies the results of these tests. As the graphs linked to this page demonstrate, the testing shows that emissions from CRRA’s trash-to-energy facilities are well below even the MACT limits. So not only does trash-to-energy extend the life of landfills, conserving natural resources, it also protects the public health.
To find out more, click on any of the links above.