California has unquie requirements though. Due to the geography of San Francisco air pollution gets trapped within the Bay Area. Combined with s high populatio

California has unquie requirements though. Due to the geography of San Francisco air pollution gets trapped within the Bay Area. Combined with s high population density a vehicle emitting the same amount of pollution will have a greater health impact within San Francisco then outside of it. Regulations are a trade off between the needs of different stakeholders. If the needs of the stakeholders differ then the regulations need to as well.