The Framework Convention on Tobacco Control requires that all public places be smoke-free. Preventing public exposure to carcinogenic second-hand smoke requires a 100 percent smoke-free environment.

Second, loopholes make smoke-free laws very difficult to effectively enforce. If single occupancy offices were exempt from a smoke-free law, then co-workers, cleaning staff, and others who have to enter these offices, or who work nearby, would be exposed to second-hand smoke. When the door to an office is open, smoke escapes and spreads, even with the door closed, smoke escapes through gaps in door frames, floorboards and ceilings, and through ducts and shared ventilation systems. Scientific evidence shows that exposure to tobacco smoke cannot be "engineered away". Ventilation systems, air filtration, and designated smoking areas are ineffective in protecting against the hazards caused by exposure to second-hand smoke.

Third, exceptions to the new regulation that provide special privileges for senior managers and officials would also reinforce the perception that China has one rule for its elite, and another for its workers.

Fourth, as the nation's capital, Beijing sets a precedent and is a role model for every other Chinese city. Beijing has an opportunity to lead the way here, to set an example for every other city in China - and other megacities across the world - to follow. This is an opportunity for Beijing to get ahead of the curve - to pass a regulation that will make Beijing a leader, not just within China, but across the world.

The legislative process has reached a crucial juncture. Beijing's lawmakers must resist any temptation to water down the city's anti-smoking regulation. The loopholes and exemptions that have appeared in the draft should be removed. Any exemption for single occupancy offices would do a disservice to Beijing's, and China's, people. Above all, exemptions would represent a grave failure by Beijing's lawmakers to protect their people from the deadly hazards of exposure to second-hand smoke.

Although a few other cities and countries have unwisely made exceptions to their anti-smoking laws, it would be a massive misstep if Beijing's legislators followed suit and repeated their mistakes. Simply stated, Beijing has an opportunity here to pass a regulation that will save lives.

The WHO urges the Beijing Municipal People's Congress to seize that opportunity, by passing legislation that bans public smoking indoors, with no exceptions.

The author is the WHO's Representative in China.