One in four Hong Kong teenagers has smoked, and second-hand smoke can aggravate respiratory symptoms even among smokers. These are the main findings of a University of Hong Kong study published in the latest issue of the journal Pediatrics.
Researchers from the university's school of public health said the study was the first to show that exposure to second-hand smoke was associated with increased risk of persistent respiratory symptoms among adolescent smokers.
Current smokers who were exposed to second-hand smoke at home for five to seven days a week were 77 per cent more likely to suffer from respiratory symptoms than those who were not exposed, researchers said. If they also encountered second-hand smoke outside home, the percentage of risk was even higher, at 85 per cent.
Some 32,506 people aged 11 to 20 were recruited from 85 randomly selected schools in 2003 and 2004 and asked to fill in a questionnaire. The survey revealed 24 per cent had smoked - 9 per cent who were currently smoking, 13 per cent who had tried smoking and 2 per cent who had kicked the habit.
More than 85 per cent said they encountered second-hand smoke outside home, whereas 51 per cent reported the same situation at home.
One in 10 non-smokers said they had suffered persistent respiratory symptoms for more than three months in the past year. The rate doubled among smokers, with 22.2 per cent reporting the symptoms.