Smoking in cars that are carrying children has already been banned in some states of Canada, Australia and the US and the whole of South Africa.
Canada's Cancer Advisory Coalition claims the states' bans on smoking in cars have reduced children's exposure to second-hand smoke by 33%.
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A band of heavy, thundery showers continues to move northwards through this evening, dying away overnight.
The Duke of Cambridge also laid a wreath to honour the victims before kick-off.
The mother of one of the Manchester attack victims has told of the distressing moment she found her daughter being treated after the attack.