Air pollution is the contamination of air by gases and particles that endanger health. Major sources include transportation engines, power generation, industrial processes, and waste burning. In cities, transportation and burning fossil fuels for energy and garbage produce ash, soot, and other particles that cause smog. Different types of air pollution include ozone smog, particles/soot. Air pollution affects health through respiratory diseases from sulfur oxides, acid rain, indoor pollution, and carbon monoxide reducing oxygen in blood. York County experiences soot pollution year-round from coal plants. Tighter regulations and individual actions can help reduce air pollution.