Ahhh, the ignorance!
The Problem
Sulfur Dioxide (SO2), along with nitrous oxides, are the two leading causes of acid rain. Acid rain refers to the process by which acids fall from the atmosphere. When SO2 is emitted into the atmosphere, it reacts with other chemicals to form sulfuric acid, which then returns to the earth in some form. The acids can then contaminate lakes and have harmful effects on animals that live near these lakes. High levels of acid in lakes and rivers can kill fish as well as make them unable to reproduce. It is believed that some lakes in Minnesota have lost all of their fish as a direct result of acid rain. Many plants and one-celled organisms near lakes with high acidity are killed as well. The death of fish, plants, and other living organisms near a lake can have a cascading effect on other wildlife that is not directly affected by the high levels of acid. Acid rain also has an effect on forests, causing trees to weaken and die much easier. Leaves and needles fall off for no reason, and forests grow much slower. While acid rain does not pose a direct threat to human health, sulfur dioxide does. Sulfur dioxide reacts to form sulfate particles which when breathed by people can cause asmtha and bronchitis. Finally, acid rain can decrease visibility and cause damage to paint and other materials. The EPA has a website which summarizes many of the problems associated with acid rain. Another site describes many of the same problems at a more basic level. The Sierra Club has a website that discusses the health problems that people face.
The Regulation of SO2 Emissions
As usual, the naysayers haven't done their homework, the talking points they get is all they need. If the ideology says one thing, the brain-washed extreme ideologues bit on it as though it must be true, without putting any effort at all in researching whether it's true or not.