The following regulations provide requirements to reduce mobile source pollution.

• Control of Air Pollution from Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards
  The Tier 3 standards are part of a comprehensive approach to reducing the impacts of motor vehicles on air quality and public health. The standards will reduce both tailpipe and evaporative emissions from all passenger vehicles and provide more stringent gasoline sulfur standards.
• Control  of  Air  Pollution  From  New  Motor Vehicles:  Tier  2  Motor  Vehicle  Emissions Standards  and  Gasoline Sulfur Control Requirements
  The Tier 2 program is part of a comprehensive approach to reduce emissions by providing protective tailpipe emissions standards for all passenger vehicles and lowering standards for sulfur in gasoline.
• Control of Hazardous Air Pollutants from Mobile Sources
  In February 2007, EPA finalized this rule to reduce hazardous air pollutants from mobile sources. The rule limits the benzene content of gasoline and reduce toxic emissions from passenger vehicles and gas cans. EPA estimates that in 2030 this rule would reduce total emissions of mobile source air toxics by 330,000 tons and VOC emissions (precursors to ozone and PM2.5) by over 1 million tons.
• Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements
  This page presents emission-related information and regulations for heavy-duty highway engines, such as those used in trucks and buses.
• Regulations related to Emissions from Aviation
  This page provides information about air pollutant emissions from aviation including aircraft emissions of lead, nitrogen oxides, and greenhouse gases. It includes regulations, guidance, and other information related to aircraft.
• Regulations related to Inspections and Maintenance (I/M)
  This page contains regulations that facilitate the implementation of the Clean Air Act mandate for vehicle I/M.
• Regulations related to Nonroad Diesel Engines
  Nonroad diesel engines are used in machines that perform a wide range of important jobs. These include excavators and other construction equipment, farm tractors and other agricultural equipment, heavy forklifts, airport ground service equipment, and utility equipment such as generators, pumps, and compressors.
• Regulations related to Locomotives and Commercial Marine Vessels
  This page provides general and technical information on the locomotive rulemakings that affect railroads, locomotive manufacturers, and remanufacturers. It also includes some regulations related to marine engines.
• Regulations related to Small SI and Marine SI Engines
  EPA standards for exhaust and evaporative emissions reduce the environmental impact from gasoline boats and personal watercraft.