People are more likely to start smoking while still at school than at any other time in their life, a 39-year study has revealed.
The popularity of taking up cigarettes is falling in all age groups except among those aged between 11 and 15.
The most common age for someone to begin the habit is now 16 for boys or 15 for girls – down from 18 and 19 respectively in 1970.
And researchers say they have seen a ‘worrying’ rise in the number of people starting smoking in their early teens since 1990.
Twice as many 11 to 15-year-old girls in Western Europe took up smoking in 2009 as in 1970.
Scientists warn anti-smoking adverts need to be aimed at younger people because people who make it to 20 years old without smoking are ‘very unlikely’ to start as adults.
People now most likely to start smoking when they are aged between 15 (women) or 16 (men), and smokers are starting younger now than they did in 1970
The study by the University of Bergen in Norway looked at information about 120,000 people from 17 countries in Europe.
The data was collected between 1970 and 2009 and recorded the age at which smokers started their habit.
On average, European smokers are now 17.2 years old when they first become hooked on cigarettes.
And the study said it was ‘worrying’ that the proportion of smokers starting before they are 15 years old rose from 17 per cent in 2012 to 19 per cent in 2014.
While two per cent of women started smoking before they were 15 in 1970, that figure had risen to four per cent by 2009.
Nicotine addiction is stronger when somebody starts smoking young, the researchers say, so it is important to target anti-smoking ads at children.
‘Anti-smoking messages have not reached young people’
‘Since 1970, campaigns against smoking seem to have been largely successful,’ said study author Cecilie Svanes.
‘But the message has not been able to reach the youngest ages.
‘Society has more to win by focusing anti-smoking campaigns on the youngest.
‘Of course, one reduces the risk of heart attack and lung cancer if you stop smoking at an old age, but society as a whole gains more by keeping the youngest age groups healthy for the rest of their life.’
If someone doesn’t start in their teens they are unlikely to smoke as an adult
The study adds that if someone can make it through their teenage years without becoming addicted to smoking they have a better chance of avoiding it as an adult.
The authors wrote: ‘Our study suggests that if youngsters reach age 20 as non-smokers, they are very unlikely to start later in life.’
Smoking is thought to cost the NHS as much as £5 billion per year because it contributes to so many serious diseases.
There are bans in the UK and Australia which make it illegal to smoke indoors unless in a private home, and some US states have similar laws.
It is also illegal to advertise cigarettes in Britain, and cigarettes are now sold in unbranded, plain green packaging with graphic health warnings.
And rates continue to fall – between 2010 and 2015 the proportion of adults who smoked dropped from 20.1 per cent to 17.2 per cent.
Boys should be discouraged in order to protect their future children
The University of Bergen researchers said it was especially important to discourage smoking among young men because it can affect their future children.
Men who start smoking before the age of 15 are more likely to have asthmatic children, even if they quit before becoming a father, the same scientists found in the past.
Professor Svanes added: ‘We have seen that for men who start smoking before they are 15, there are influences on any future children. For example, their offspring get asthma more often than others.
‘In animal tests we have also seen that it is the nicotine itself that causes the higher risk.
‘If this is the case for humans as well, it means that neither snuff nor e-cigarettes are good alternatives to cigarettes, at least not for the youngest age group.’
The team’s findings were published in the journal PLOS One.