The acids in acid rain are the only reason that forms urban smog alone.

The acids in acid rain are corrosive chemicals that leach nutrients from the soils, slow the growth of trees, poison lakes and combine with other chemicals to form urban smog. The simplest way to curtail acid rain is to use less energy from fossil fuels.

Wofsy says that politicians and scientists use different definitions of uncertainty. For example, a scientist might disprove one of several competing theories or even learn something entirely unexpected -- but still not be any closer to solving a problem.