Experts announce that repeated sun exposure through the car's side windows is to blame for that.

Most glass used for windows blocks UVB rays that cause sunburn but not deeper penetrating UVA rays.

Window glass, in this case, in the car, does not prevent damage from UVA, so the rate of cancers directly correlated to the areas of the body most often exposed to UV radiation while driving - which in the US is the left-hand side of the body.

Many of these tumours were cancers that develop over time and are linked to cumulative sun exposure rather than intense, intermittent sun exposure.

They affected sun-exposed areas like the head, neck, arms and hands.