BEIJING — China’s capital Monday began imposing the country’s toughest ban on indoor smoking in hopes of stemming a looming health crisis.

Smoking in Beijing is now prohibited in all indoor public places, including offices, shopping malls and airports. Beijing’s main terminal will close its three smoking rooms and special smoking areas will be set up at the city’s 600 bus stops.

Fines for violators have been raised to 200 yuan ($32), up from the 10 yuan ($1.6) charged under the former partial ban.

The World Health Organization says 300 million Chinese smoke, including about half of all men, and 740 million Chinese are exposed to second-hand smoke. The group says lung cancer kills more than 1.3 million people in the country each year, one-third of the global total.

Bans have been imposed in other parts of the country and cigarette sales to minors are technically forbidden, although enforcement is spotty at best.