汽车是当前主要的运输工具。据统计,全世界各种运输工具中汽车占90%。汽车尾气及噪声对环境的污染是当前的一大危害。汽车的尾气排放与车型、燃料、行驶状况、路面条件等因素有关。慢速行驶或发动机停挡空转,因燃料不能充分燃烧,排气管冒黑烟,其中含5%的一氧化碳。快速行驶时,汽油高温燃烧,冒的烟含氮氧化物最多。不过,尾气中危害最大的是光化 The car is currently the main means of transport. According to statistics, 90% of all kinds of vehicles in the world transport vehicles. Car exhaust and noise pollution on the environment is a major hazard. Vehicle exhaust emissions and models, fuel, driving conditions, road conditions and other factors. Slow running or engine stalling idly, because the fuel can not be fully burned, the exhaust pipe black smoke, which contains 5% carbon monoxide. When driving fast, the gasoline burns at high temperatures and smoke most of the nitrogen oxides. However, the most harmful emissions is photochemical