Unit 4. Acid rain. I hate this rain. It's causing the traffic to back up for miles. Well, I hate this traffic because it's helping turn this rain into acid rain. I heard that acid rain has really bad effects. Doesn't it cause cancer and brain damage and even Alzheimer's disease? It definitely can, but the major thing it does is cause breathing problems. The acid in the rain comes from smoke and gases that are given off by cars and factories. It's like riding your bike behind a bus that's showering you with its exhaust fumes. Oh, I was reading something about that the other day. It said there's too much sulfur in the air and that it's killing thousands of people every year. Yes, sulfur is the major element in factory and car exhaust. It combines with oxygen and nitrogen in the air to become the acid in acid rain. This stuff doesn't just kill us, you know. It also kills trees and lakes and animals. The acid soaks into the plants and animals so that anyone who eats the plants and animals is also eating the acid. This sounds terrible. What can people do to stop acid rain? One simple thing they could do is to use less energy. Another way to stop acid rain is to drive less, or at least carpool. Imagine if every car on this road had four people in it right now. There would be fewer cars and a lot less acid rain.