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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He has asked his followers for help in tracking the man down.
The president said it was a “very sad day for journalism”.
A summit has been pencilled in for February following last year’s icebreaker in Singapore.