The Clean Air Act of 1970 made rules for getting sulfur from oil refining, processing of sulfide, ores, and even the combustion of electricity generation. This required technologies to be made in order to coincide with the Clean Air Act.
The Clean Air Act of 1970 set rules for removing sulfur from oil refineries, processing sulfide ores, and even power plant emissions.  This prompted the creation of new technologies to meet these requirements.