The document discusses various environmental problems affecting the world, including acid rain, air pollution, global warming, hazardous waste, ozone depletion, smog, water pollution, overpopulation, and rainforest destruction. It provides details on the causes and effects of acid rain, noting that it is caused by sulfur dioxide and nitrogen oxide emissions from industries and vehicles. The summary describes how acid rain harms aquatic ecosystems and damages trees and plants. It also mentions that acid rain corrodes certain materials like limestone and metals.