Vehicle emission standards are regulations set by governments to control the amount of pollutants that vehicles can emit into the atmosphere. These standards aim to reduce harmful substances, such as carbon monoxide, nitrogen oxides, and particulate matter, which can contribute to air pollution and health problems. To comply with these standards, manufacturers must design vehicles that meet specific emission limits during testing. Environmental Protection Agency (EPA) in the United States and similar organizations in other countries enforce these regulations, promoting cleaner air and encouraging the development of more efficient and environmentally friendly automobiles.