Zero emissions refer to vehicles that produce no tailpipe pollutants, such as carbon dioxide (CO2), nitrogen oxides (NOx), or particulate matter. Battery electric vehicles (BEVs) and hydrogen fuel cell electric vehicles (FCEVs) are considered zero-emission vehicles (ZEVs) because they do not rely on the combustion of fossil fuels. While the production of electricity or hydrogen may result in emissions, the operation of these vehicles produces none, contributing to cleaner air and reduced greenhouse gas emissions. ZEVs are a key component of efforts to mitigate climate change and improve urban air quality.