Emission Control and Air Pollution Module

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Timetable for Selected Mobile Source Provisions of the 1990 Clean Air Act


  • Limits on maximum gasoline vapor pressure became law nationwide.
  • Regulations setting minimum oxygen content for gasoline took effect in areas where carbon monoxide levels exceed national pollution standards.


  • Production of vehicles requiring leaded gasoline became illegal.
  • New standards for sulfur content of diesel fuel took effect, reducing the maximum sulfur level by 80 percent.


  • Phase-in of tighter tailpipe standards for light-duty vehicles begins.
  • Enhanced Inspection and Maintenance programs begin in some polluted cities.
  • Phase-in of cold temperature carbon monoxide standards for light-duty vehicles begins.
  • Trucks and buses must meet stringent diesel particulate emission standards.
  • New cars must be equipped with onboard diagnostic systems.


  • Reformulated gasoline provisions take effect in the nation's smoggiest cities and in other areas that voluntarily join the program.
  • New warranty provisions on emission control systems take effect.


  • Phase-in of California Clean Fuels pilot program begins.
  • Lead banned from use in motor vehicle fuel.
  • All new vehicles (1996 model year cars and light trucks) must meet new tailpipe and cold-temperature carbon monoxide standards.


  • Clean-fuel fleet programs begin in ozone and carbon monoxide non-attainment areas in 19 states.


  • Second phase of the Fleets and California Pilot clean fuels programs begin.