They also face pollution from particulate matter, like vehicle exhaust or wildfire smoke, which can enter classrooms from the outside.

他们还面临着来自颗粒物的污染，比如汽车尾气或野火产生的烟雾，这些颗粒物可能会从室外进入教室。

That`s a toxic gas which comes from vehicle exhaust.

那是一种来自汽车尾气的有毒气体。

China's environmental watchdog has pledged to curb vehicle exhaust emissions as hazardous air pollution has shrouded parts of the country in recent days.

中国环境监督机构表示，近日来全国部分地区的空气污染达到危险级别，因此中国将加大力度防治机动车尾气污染。

This nocturnal launch, dictated by the vagaries of celestial mechanics, gave rocket-watchers a rare treat, as the vehicle's white-hot exhaust lit up the countryside for miles around.

由于天体力学的变幻莫测，这种夜间发射给火箭观察者带来了难得的享受，因为火箭白热的废气照亮了方圆数英里的乡村。