The contact group on motor vehicles, particularly those burning leaded gasoline, noted that a study conducted in the United Kingdom had provided new information on diesel engine emissions.

Indeed, it was Ronald Reagan s administration that pioneered the use of cap and trade to phase out leaded gasoline in the 1980 s. George H. W. Bush s administration used it to reduce SO2 emissions from power plants in the 1990 s, and his son s administration sought to use it to reduce SO2 and other emissions further in the 2000 s.