The original Clean Air Act was established by the Environmental Protection Agency (EPA) in the 1970s. At the time, there were few, if any, provisions made for the reduction od acid rain causing gases. Basically, the Clean AIr act was the first major legislation aimed at cleaning up our air. Later, there were amendments made to the act. It is in these amendments that we obtained regulations for the production of both SO2 and NOx.
EPA released amendments to the Clean Air Act. In these amendments, EPA made provisions for acid rain, commonly known as Titile IV. Although the provisions affect only a small amount of the sources of acid rain gases, the improvements caused are expected to be significant. With the creation of Title IV, EPA implemented two new concepts. These concepts are:
1. Emissions Trading
2. National Emissions Cap
In order to accomplish its goals, Title IV established a nationwide system of SO2 emission allowances. These allowances are expressed in terms of tons of SO2 emitted per year, and the basic allowance is emission of 1 ton per year of SO2. It is important to note that no source affected by Title IV can emit SO2 without holding an allowance for the emission. If a source does this, it may have to face judicial action. Also, if a source want to increase production and therefore increase emissions, it must obtain an emission allowance from another source that has reduced emissions. This is known as emissions trading.
In addition to the SO2 reduction, Title IV calls for a 2 million ton reduction in NOx. This reduction will be accomplished through burner modifications and will be measured from the amount of NOx that would have been emitted, if no modifications had been made. In terms of NOx emissions, Title IV does not require that industries install post combustion controls for monitoring. Also, unlike the SO2 emission reduction program, there is no NOx emission allowance system or emission cap for NOx.