Mercury and Air Toxics Standards

Environmental Training Resource
May 17, 2012 — 1,274 views  
Become a Bronze Member for monthly eNewsletter, articles, and white papers.

Though the air generally smells and looks clear, there could be an unknown number of toxic gases swirling around in any given location. Carbon monoxide, radon and other poisonous fumes are dangerous because they can only be detected with special instruments. The U.S. government has strict guidelines when it comes to regulating our breathable air, and recent updates to official legislation must be noted by those in the environmental, power and construction industries.


Mercury and Air Toxics Standards (MATS) are mandated by the federal government and have been in the approval process since the turn of the decade, although numerous other air regulations have been around since the 1990s. The Environmental Protection Agency (EPA) states that these strict guidelines are designed to reduce air pollution from coal and oil-fired power plants.

Coal, oil and natural gas provide much of the energy in the U.S., and electric generating units (EGUs) larger than 25 megawatts are targeted by MATS regulations. Power plants using these materials generally have four years from the date of their initial inspection to adhere to MATS guidelines, though this can be reduced based on the level of potential hazards.

MATS came into effect very recently, as the Environmental Protection Agency (EPA) was required to issue a final ruling by December 16th, 2011.

Clean Air Act

Current MATS legislation elaborates on sections 111 (the new source performance standards) and 112 (the toxics program) of the Clean Air Act, which was itself established in 1963 in a simplified form. Two major revisions in 1970 and 1990 brought the legislation up to date, and MATS is the next step in regards to heavy metals standards.

The Clean Air Act covers all 50 states and the outlying territories of the United States, and all power plants must meet the guidelines set by this law. In addition, the EPA must evaluate and approve any plans designed to limit air pollutants, and any rejection can result in heavy financial consequences and the potential closure of a plant.

The language of the Clean Air Act defines six "criteria pollutants"  that must be controlled. These include particle pollution (often referred to as particulate matter), ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides and lead, according to the EPA. Geographic zones that adhere to the regulations are designated as "attainment" areas, while those that do not meet Clean Air Act standards are identified as "non-attainment" areas.

Environmental Training Resource