1.   Cars are a major cause of air pollution.

2.   Conclusions Cigarette smoking is a major cause of arterial disease, whether of the heart, brain or legs.

3.   Excessive speed is a major cause of road accidents.

4.   Fumes from cars are a major cause of air pollution.

5.   However, over-exposure to the sun or insufficient protection is a major cause of premature skin ageing.

6.   In this country, debt is a major cause of homelessness.