Raising the legal age for tobacco purchase from 18 to 21 years is likely to reduce smoking rates in young people and make the generation smoke-free, experts suggest.
Most smokers start smoking during childhood and two-thirds of those who try smoking early will become regular smokers later, said the study published in The BMJ.
Increasing the legal age to 21 would make it harder for children to obtain cigarettes and take the legal age beyond school age, said Nicholas Hopkinson, respiratory specialist from the Imperial College London.
"Smoking is a contagious habit transmitted within peer groups, and the age increase will protect younger children from exposure to older pupils in school who smoke. It will also remove a potential source of supply within schools," said Hopkinson.
He stressed that besides helping existing smokers to quit, preventing young people from taking to smoking is imperative.
Hopkinson also suggested that a "polluter pays" tax set to raise around $198 million per year from tobacco manufacturers will help to pay for a revitalised, evidence-based set of tobacco control policies.
"This could include the introduction of a retail licensing scheme for tobacco products, which could help limit underage sales. It would also make it easier to ban sales from those who break the law," Hopkinson said.