Gasoline engines aren't as powerful as diesel engines, so buses, trucks and other large vehicles generally run on diesel fuel, which is a much heavier pollutant.
汽油引擎先天上載重力不如柴油引擎，因此大客車、大貨車等載重大的運輸工具，大多是柴油引擎，它對人體的傷害又比汽油車嚴重。