MACT – means Maximum Achievable Control Technology. The emission standard for sources of air pollution requiring the maximum reduction of hazardous emissions, taking cost and feasibility into account. Under the Clean Air Act Amendments of 1990, the MACT must not be less than the average emission level achieved by controls on the best performing 12 percent of existing sources, by category of industrial and utility sources.

MANE-VU – means Mid-Atlantic/Northeast Visibility Union. MANE-VU was formed by the Mid-Atlantic and Northeastern states, tribes, and federal agencies to coordinate regional haze planning activities for the region.  MANE-VU provides technical assessments and assistance to its members, evaluates linkages to other regional air pollution issues, provides a forum for discussion, and encourages coordinated actions. MANE-VU also facilitates coordination with other regions.

MARAMA – means Mid-Atlantic Regional Air Management Association. MARAMA is a voluntary, non-profit association of ten state and local air pollution control agencies. MARAMA's mission is to strengthen the skills and capabilities of member agencies and to help them work together to prevent and reduce air pollution in the Mid-Atlantic Region.

Maximum gross heat input rate – means the maximum amount of fuel a combustion source is able to combust in a given period as stated by the manufacturer of the combustion source.  This term is expressed in BTUs per hour, based on the highest BTU value of the fuels combusted. 

Mercury (Hg) - Heavy metal that can accumulate in the environment and is highly toxic if breathed or swallowed.

Mobile equipment – means equipment which may be driven or is capable of being driven or pulled on a roadway including, but not limited to, automobiles, trucks, including truck cabs, truck bodies and truck trailers, buses, motorcycles, camper shells, mobile cranes, bulldozers, street cleaning machines, golf carts, ground support vehicles used in support of aircraft activities at airports, and farm equipment.

Monitoring – Measurement of air pollution is referred to as monitoring.  EPA, state and local agencies measure the types and amounts of pollutants in community air.  The 1990 Clean Air Act requires certain large polluters to perform enhanced monitoring to provide an accurate picture of their pollutant releases.

Motor vehicle -- means every device in, upon, or by which a person or property is or may be transported otherwise than by muscular power, excepting such devices that run only upon rails or tracks and motorized bicycles.

MPO – means Metropolitan Planning Organization.   Under federal legislation (see TEA-21), MPOs provide a forum where local officials, public transportation providers and state agency representatives can come together and cooperatively plan to meet a region's current and future transportation needs. Each MPO establishes its region's eligibility to receive federal tax dollars for transportation projects. MPOs carry the lead responsibility for developing transportation plans and programs for urbanized areas of 50,000 people or more.

MW – means megawatt.