Vital to state implementation plans (SIPs), control analyses evaluate the availability and appropriateness of certain control measures in order to lower emissions in a nonattainment area. Control measures, or the actions taken to limit the amount of pollution emitted from sources, are required by laws and/or rules and can necessitate changes in technological equipment or operating procedures.

In order to determine what kind of control measures are needed for a particular area, the SIPs Section conducts an analysis of the economic and technological feasibility of controls available in EPA’s Clearinghouse as well as those implemented in other states.

Many types of controls are associated with the New Source Review (NSR) program. The NSR program evaluates new and existing sources of emissions that are located in nonattainment or attainment areas. Each state is responsible for implementing control technologies for these sources through statewide NSR programs. The controls fall into different categories and are applied to emitting sources on a case-by-case basis. Maintenance and nonattainment SIPs can also analyze control measures. 

Types of controls that are included in an analysis are:

Reasonably Available Control Measures

Generally, Reasonably Available Control Measures (RACM), are available for nonattainment areas and the related emission sources. These measures are actions taken by sources to lower emissions down to an allowable amount as mandated by the area’s SIP. RACM is a giant menu of control measures a state can consider when compiling a SIP for an area. RACM can apply to minor or fugitive sources of a pollutant.

Reasonably Available Control Technology

Part of the RACM menu is Reasonably Available Control Technology (RACT). RACT is required on existing major stationary sources in nonattainment areas after considering the feasibility of the control technology. RACT is usually physical technology a source can install on the emitting equipment in order to bring the area back into attainment so that good air quality is achieved.

Best Available Control Measures

Best Available Control Measures (BACM) are one step up from RACM. BACM is also a menu of actions taken by sources that will further limit emissions. BACM are generally used when an area cannot attain the standards by only implementing RACM. BACM can also be implemented on new sources that will be located in attainment areas in order to preserve the good air quality. 

Best Available Control Technology

Part of the BACM menu is Best Available Control Technology (BACT). The technological controls categorized as BACT is stronger than those in RACT and is designed for new or modified major sources in an attainment area.

Lowest Achievable Emission Rate

The Lowest Achievable Emissions Rate (LAER) is the lowest possible emissions threshold for a new or modified major source in a nonattainment area. Controls categorized as LAER reduce emissions from sources contributing to an area’s poor air quality. LAER controls are the most stringent and do not take economic or technological feasibility into account.