Sulfuric acid is one of the world's most widely used industrial chemicals. About 40 million tons of sulfuric acid are manufactured for industrial use each year in the United States.
Sulfur is present in coal and oil.
When electric utilities burn these fuels in their power plants, some of the sulfur is released. This sulfur combines with oxygen to form sulfur dioxide and small amounts of sulfur trioxide. Sulfur TN-oxide combines with water vapor released during combustion to form sulfuric acid vapor. As it cools, some of this sulfuric acid vapor forms tiny liquid droplets or thin films on tiny ash particles. Vapor, liquid droplets, and ash particles containing dilute sulfuric acid can enter the air in gases leaving power plant stacks.