RACM – means Reasonably Available Control Measure. A broadly defined term referring to technological and other measures for pollution control.

RACT – means Reasonably Available Control Technology. Control technology that is reasonably available, and both technologically and economically feasible. Usually applied to existing sources in nonattainment areas; in most cases is less stringent than New Source Performance Standards (NSPS).

Regional Greenhouse Gas Initiative (RGGI) – A cooperative effort by Northeastern and Mid-Atlantic states to reduce carbon dioxide emissions. The RGGI states will develop a regional strategy by April 2005 for controlling emissions. This strategy will more effectively control interstate transport and international transport of greenhouse gases, and will require electric power generators in participating states to reduce carbon dioxide emissions.

Reformulated gasoline (RFG) – specially refined gasoline with low levels of smog-forming volatile organic compounds (VOCs) and the low levels of hazardous air pollutants. The 1990 Clean Air Act requires sale of reformulated gasoline in the nine smoggiest areas. Reformulated gasolines were sold in several smoggy areas even before the 1990 Clean Air Act was passed.

RFP – means Reasonable Further Progress. Annual incremental reductions in air pollutant emissions as reflected in a State Implementation Plan that the USEPA deems sufficient to provide for the attainment of the applicable national ambient air quality standards by the statutory deadline.

RTP – means Regional Transportation Plan. The federally mandated long-range transportation plan for the region. It sets out a vision for development of the transportation system over the next twenty years and serves as an investment guide for the region. Updated every three years.

RH – means Regional Haze. The haze produced by a multitude of sources and activities, which emit fine particles and their precursors across a broad geographic area. The U.S. regulations require states to develop plans to reduce the regional haze that impairs visibility in Class I areas.

ROP – means Rate of Progress.

RRF – means Relative Reduction Factor.