Emission standards existing installations

F. Emission Standards for Existing Installations in the United States... 

The states and cities of the United States sometimes have emission standards for existing installations, which are usually less restrictive than those... 

Existing stationary sources may require modification of existing systems or installation of newer, more efficient control devices to meet more restrictive emission standards. Such changes are often required by control agencies when it can be shown that a new control technology is superior to older... 

Titles I and IV are most relevant to SO, and NO control. Title I establishes a 24-hour average ambient air standard for SO, of 0.14 ppm. The NO provisions require existing major stationaiy sources to apply reasonably available control technologies and new or modified major stationaiy sources to offset their new emissions and install controls representing the lowest achievable emissions rate. Each state with an ozone nonattaininent region must develop a State Implementation Plan (SIP) that includes stationaiy NO emissions reductions. 

Nonattainment Requirements. Currently, there are roughly 100 areas of nonattainment for O3, over 40 for CO, and 70 for particulate matter. Also, there are a number of areas not in compliance with SO2 standards. Thus, existing or proposed new or modified industrial facih-ties located in or near these areas wiU be subject to a variety of new requirements designed to limit existing and future emissions of these nonattainment pollutants. Eor certain existing sources, reasonably available control technology (RACT) requirements have or will be imposed.The construction of a new or modified source may require the installation of LAER technology and emission offsets. 

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