The Clean Air Act requires the Environmental Protection Agency (EPA) to regulate pollution from new, modified and reconstructed facilities through the New Source Performance Standard s (NSPS) program, established in Sec. 111 of the Act. NSPS are technology-based standards which apply to specific categories of stationary sources. The new standards lower the amount of particulate matter (PM), sulfur dioxide (SO2), and dioxides of nitrogen (NOx) that can be emitted. Under Sec. 111(b) , EPA must establish performance standards for new and modified sources. An NSPS requires facilities to attain an emissions level that "reflects the degree of emissions limitation achievable through the application of the best system of emissions reduction which (taking into account the cost of achieving such reduction and any nonair quality health and environmental impact and energy requirements) the Administrator determines has been adequately demonstrated." In setting this performance standard, EPA has some discretion to distinguish among classes, types, and sizes within source categories. However, the limit EPA sets must take the form of a standard and may not prescribe a particular technology itself. Under the law, EPA is to review the technological options available for emissions reduction and, if appropriate, establish a new standard every eight years. In practice, standards remain in place for longer than eight years.
As with some other Act programs, the Federal government establishes and state air quality programs implement NSPS programs.
The Cement NSPS will set new standards of emissions for any new cement manufacturing plants (kilns or clinker coolers) or major modification to any of the 97 existing cement manufacturing facilities in all regions of the United States. Emissions standards issued in 2010 include limits on emissions of mercury, hydrocarbons, particulate matter, and hydrochloric acid. EPA estimates that twenty new facilities may be built in the five years following promulgation of the rule and would, therefore, be subject to the new regulations.
The first NSPS for cement plants was issued in 1971, and reviews were made twice in 1974 and once in 1988. This most recent review was started as a proposed rule in June 2008 under the Bush Administration. EPA finalized the new NSPS in September 2010 as a joint rulemaking with a new MACT for cement plants. On February 12, 2013, EPA issued a final MACT and NSPS rule for cement plants that made modifications to the 2010 rule. The new rule extended the compliance period from 2013 to 2015, changed the way particulate matter emissions are monitored, and made other changes.
Read more from EPA  on Cement NSPS.