Though the acid rain-awareness campaign has made this less of an issue than it was in the past, it's still a major pollution problem. A quick refresher on the how: the burning of fossil fuels releases compounds that interact with the H20 in the air, creating a modified version of the raindrop—one that includes nitric and sulfuric acid, which pollutes the water and ground that's affected by the rain. Too much of those acids inhibits plant growth, and soil damage on a major scale would take eons to repair—which makes soil a "non-renewable resource," according to the U.S. Geological Survey.