Around one fifth of Switzerland's population was exposed to second-hand smoke for one hour per day last year, according to the latest Federal Health Office findings.
Young people aged 14 to 24 were the most affected, mainly because they spent time in more smoky environments, such as bars. They also have the highest percentage of smokers, at 37 per cent.
However, this age group said they considered themselves to be less at risk from second-hand smoke than others, the Health Office reported in its Tobacco Monitoring Survey.
Exposure to passive smoking has continued to drop for the population as a whole. In 2002, 35 per cent said they were affected and in 2006, it was 27 per cent.
Passive smoking was most likely to occur at catering establishments and its incidence in workplaces has fallen as a result of many companies outlawing smoking, authorities said.
Overall, more than two-thirds of those surveyed said they supported a ban on lighting up in restaurants, cafés and bars. In cantons where it is already outlawed, 90 per cent were in favour.
The southern Italian-speaking Ticino region became the first canton to introduce a smoking ban in indoor public places in April 2007.
Currently, nine cantons have introduced bans and most others are planning similar legislation, although there is no consistency nationwide.
swissinfo.ch and agencies