The subject of emissions regulations is complex. Worldwide there are over 20 countries that regulate permissible emissions, each with its own regulations. Certain groups, such as the European Economic Community (EEC) have regulations for all of their members. In the United States, federal regulations (Fig. 1) fall under the Environmental Protection Agency (EPA), while there are separate regulations for each of the 50 states. Fortunately, most of the state regulations are simply adapted from and are quite similar to federal regulations. However, several states have significantly more stringent standards than the federal regulations. The State of California, for example, not only has separate regulations, but each of the 45 pollution control districts within the state has its own regulations, most of which differ substantially from each other.
The following is a discussion of the U.S. federal regulations as they apply to areas that presently meet the ambient air quality standards. These are called attainment areas. Areas that do not meet the ambient air quality standards are called nonattainment areas. For a gas turbine application in a nonattainment area, such as Denver, or in the State of California, it is imperative to check local regulations, which result from the federal regulations for nonattainment areas.