Smoke Stacks    

Smoke stacks are very common in factories. The long tower is where smoke and other waste come out and mix with the moisture in the air to create acid rain. "Researchers now know that acid rain causes slower growth, injury, or death of forests. Acid rain has been implicated in forest and soil degradation in many areas of the eastern U.S., particularly high elevation forests of the Appalachian Mountains from Maine to Georgia that include areas such as the Shenandoah and Great Smoky Mountain National Parks." (http://www.epa.gov/acidrain/effects/forests.html)