Emission test stations are important because they verify vehicles are not emitting too many harmful gases into the environment. They serve to reduce air pollution and decrease health risks for people and animals exposed to vehicle emissions.
Harmful gases that can have negative effects on animals and plants include hydrocarbons, carbon monoxide, nitrogen oxides, particulates and sulphur oxides. Dangerous exposure to these gases can cause respiratory problems, cancer and liver disease. Environmental Protection Agency studies have shown vehicle emissions contribute to ozone layer depletion and ground-level plant health problems. Each state governs emission testing and regulations, but the EPA sets the federal standards.