|Have you ever smelled the exhaust coming out of a truck or school bus? Have you ever seen thick smoke pouring from a factoryís smokestack? Exhaust and smoke often contain unhealthy chemicals that pollute the air. To pollute means to make something dirty or impure or unsafe. |
Cars, buses, and trucks are one cause of air pollution. Their engines burn fuel, usually gasoline. From their exhaust pipes these vehicles put out unhealthful emissions. Emissions are what cars and other vehicles put in the air as a result of burning fuel in their engines. Imagine a city full of cars, trucks and buses, every one of them burning fuel and releasing emissions. Thatís one big reason why the air in many big cities is polluted. When city air gets so dirty that the sky starts looking brown, it is called smog, a word made up of two words smoke and fog. If people breathe in too much smog it can hurt their lungs.
Directions: Answer the following questions.