Expert: Dana Krempels, Ph.D. - 6/30/2007

Question
Why is acid rain more of a problem today then 100 years ago?

Is it related to the fact that 100 years ago there were no vehicles etc... or industrial parks? or were there some but not as many?

Answer
Dear Gina,

You are exactly correct.  The emissions caused by the burning of fossil fuels cause sulfur and nitrogen compounds to float in the air. When these dissolve in rain, they combine with the water to produce sulfuric or nitic acid--both very caustic and not good for living tissues.

In areas where smog is bad, acid rain is worse.  

It's only been since the Industrial Revolution that such compounds started being pumped into the air by humans in such a steadily increasing amount.  Before that, there was little or no such chemical interaction between rain and atmospheric compounds, except in such rare events as a volcanic eruption.  But once we started burning fossil fuels, the sulfur and nitrogen compounds in the air began to increase steadily in concentration until they were there in sufficient quantity to create the problem we see today.

Acid rain started being noticed in the early 1970's by researchers.  It's not going to go away any time soon, though improved vehicle emission standards are helping to lessen the problem.

Hope that helps.

Dana