REYKJAVIK• Kristjan Johannesson, 15, says he has never had a drop of alcohol or touched a cigarette.

At an age when many teenagers lock themselves in their rooms, he likes to spend as much time as possible with his parents and the walls of his bedroom are plastered with his proudest exploits in fishing and football.

He illustrates how Iceland has nearly eradicated abuse of alcohol, tobacco and drugs among teens in two decades, through measures such as imposing curfews, raising the age of majority and promoting sports.

It is a stunning turnaround for a country that discovered worrying trends among its youth in the 1990s. Nearly half of 15- and 16-year-olds surveyed at the time said they had drunk alcohol in the past month, one in four smoked tobacco and 17 per cent said they smoked cannabis.

Then, "anybody walking in the streets of Reykjavik would be scared on a Friday or Saturday night", said American psychologist Harvey Milkman, who has been involved in the project since its launch.

He said: "Teenagers were walking around drunk and they were rude, they were loud and boisterous. It seemed even dangerous. So the whole society got concerned, not just the parents."

Sociology professor Helgi Gunnlaugsson at the University of Iceland said the high figures came as a "shock" to many. "It was like a wake-up call," he said.

In 1997, the government launched the Youth In Iceland initiative, under the direction of Mr Jon Sigfusson, who heads the Icelandic Centre of Social Research and Analysis.

It used questionnaires to build a credible snapshot of a generation.

Participants, who gave their ages but remained anonymous, were asked when they had last had an alcoholic drink, whether they had ever been drunk or tried smoking, and, if so, how often. They were also asked about time spent with their parents. Within a few years, the authorities and social workers felt they knew enough to take concrete action.

Thirteen- to 16-year-olds were banned from being outside unaccompanied after 10pm and the start of the curfew was extended until midnight during Iceland's summer of long days and bright nights.

Lawmakers raised the age of majority by two years to 18, prohibited sales of tobacco to minors and alcohol to anyone under 20.

Cigarettes are not displayed in shops and are among the priciest in Europe: €9 (about S$13) a pack on average. As in most Nordic countries, alcohol is sold only in state-run stores and taxed at more than 80 per cent.

The government also promoted sports and a healthy, wholesome lifestyle. In the capital of Reykjavik, each family receives an annual allowance of 35,000 kronur (about S$430) for a child between the ages of six and 18 for extra-curricular activities, including sports.

Many Icelanders see the emphasis on sporting activity as a factor in the rise in popularity of football on the small North Atlantic island, whose national team humiliated England in Euro 2016.

"I'm really happy to just play football with my friends and train hard," says Kristjan, who practises five times a week on the artificial turf in Breidholt, a neighbourhood in southern Reykjavik.

The programme also advocated "more closeness, attention and sharing" within the family, Mr Sigfusson said. It encouraged schools to be involved with teens' behaviour too.

"We do more things with our children than (families) did in the past," says Kristjan's mother, Ms Asdis Mikaels, who enjoys bowling parties with her son.

Within eight years of the programme's launch, the figures of alcohol, tobacco and drug consumption fell by a little over 50 per cent, Mr Sigfusson said.

By last year, the percentage of young people who reported drinking in the past month had dropped to 5 per cent, regular smokers dropped to 3 per cent and 7 per cent said they used cannabis.

Although it is in line with current trends in Europe, Iceland is the only country where the change has been so dramatic.

AGENCE FRANCE-PRESSE