IT was always going to an inflammatory affair - eight smiling schoolchildren with a mission to stamp out smoking on a ferry route notorious for its assertive smokers. The enthusiastic teenagers from the Chiu Chow Secondary School looked the picture of health as they boarded the 4.35pm Hongkong Ferry from Central to Yung Shue Wan, Lamma Island. Adorned with bright yellow sashes extolling the virtues of a ''smoke-free journey'', the anti-smoking ''ambassadors'' handed out no-smoking stickers and educational material to unsuspecting passengers. Monday saw the first day of a week-long operation coordinated by the Hongkong Council on Smoking and Health which will see schoolchildren acting as ''ambassadors'' on a different ferry route every day. The ferry was less than full and passengers were a mixture of Chinese and Westerners. Most of them responded to the youngsters with bemused smiles, some gave encouragement, but inevitably a few were less than impressed. One passenger reacted strongly to being asked to put out his cigarette before the boat had even left the harbour. ''I'll stop smoking when the boats stop smoking,'' said Lamma resident Mr Paul Slough while pointing to the grey exhaust belching out from the boat. He has the distinction of being one of only two people to be charged for smoking on the ferries since the legislation was imposed, but he said he had yet to receive an official summons. One ambassador, Lam Ka-lai, 16, looked shaken as Mr Slough unleashed his complaints against the ferry company to route supervisor Mr Tony Kan Sau-shun. But Ka-lai insisted that she was not scared: ''I just wish I could speak English because I would have told him that what he was doing was against the law. He has the right to smoke if he wants, but he should not do it on the ferry,'' she said. Hongkong Ferry spokesman Mr Edward Kwan Hing-yuen said Mr Slough's reaction was an exception rather than the rule: ''Most of our customers are very co-operative and stop smoking when we ask them to without a fuss.'' But Mr Kan admitted ferry staff occasionally met resistance. ''Particularly on this route,'' he added. The company and COSH hope the campaign will raise public awareness and put an end to smoking on ferries which was ruled an offence punishable by a maximum fine of $5,000 last August. But, Mr Kwan said admits, it will be tough going. He hopes the Government will put more resources into public information and education. He also believes legislation would be more effective if a flat fine were imposed. In the meantime, the ambassadors' campaign could raise awareness rather than just act as a one-week deterrent. ''We hope people will respond more positively to students than they would to ferry staff. It is not our intention to be confrontation but to advise and educate,'' Mr Kwan said. But Mr Slough accused the company of putting the children at risk: ''I think it is provocative and dangerous for the children to confront some of the passengers,'' he said. On Monday, fortunately, there was no violence and on the whole, the sailing passed without aggravation. Those passengers who had intended to light up resisted. One old man walked on board with a pipe in his hand but as soon as he was approached, he put the offending object back into his pocket. A young Chinese man discreetly looked around to check nobody was watching. When he was satisfied the coast was clear, he picked up a packet of cigarettes and a lighter from the table where he was seated and put them back in his briefcase. Miss Mariana Law Po-chu, of COSH, was pleased with the students' achievements: ''The children have acted as an effective reminder,'' she said.