[Balding_Eagle]

thanks to strict emission control rules imposed between the 1970’s to 1990’s.

The reduction in emissions was thanks to an inventive spirit Americans possess.

Although the catalyst, Big Government is the bad guy in the story.

[RayChuang88]

They had to anyway because the oxides of sulfur from burning coal was literally damaging buildings and poisoning lakes (it was essentially a gaseous form of sulfuric acid, and we all know how corrosive this acid is).