`1.` Air pollution.

`-` Dẫn chứng: Air pollution is a cause of ill-health in human beings. 

`2.` factories.

`-` Dẫn chứng: . In a lot of countries there are laws limiting the amount of smoke which factories can produce.

`3.` Yes, it can.

`-` Dẫn chứng: Although there isn't enough information on the effects of smoke in the atmosphere, doctors have proved that air pollution causes lung diseases.

`4.` The gases from the exhausts of cars.

`-` Dẫn chứng: The gases from the exhausts of cars have also increased air pollution in most cities. 

`5.` Because the gases in the atmosphere continue to increase.

`-` Dẫn chứng: If the gases in the atmosphere continue to increase, the earth's limate may become warmer.