A generation ago, smoking was common across the world. People smoked in restaurants, bars and workplaces - as you see in many parts of China today. Even if you didn't smoke, you were often forced to breathe the secondhand smoke of others. Many countries have now moved to fix this problem, in light of the unequivocal scientific evidence of the harm caused by exposure to tobacco smoke.

Yet in China, close to 740 million people - including 182 million children - are exposed to secondhand smoke at least once a day. While Chinese women have much lower rates of smoking than men, they have some of the highest rates of exposure to secondhand smoke in the world. An estimated 100,000 people die every year in China because of secondhand smoke, in addition to the 1 million who die as a direct result of tobacco use.

Science has told us for decades that tobacco kills - 6 million people every year globally, to be precise. The science is equally clear about the harm caused by secondhand smoke: there is no safe level. Every time you breathe in secondhand smoke you are inhaling 7,000 chemicals and 69 known carcinogens, and risking lung cancer, heart disease and strokes. In babies and children, secondhand smoke can cause sudden infant death syndrome, low birth weight, respiratory problems and ear infections.

This is an urgent public health problem in China. But the good news is that it is a problem with a readily available solution: a national smoke-free law.

Our new report lays out the case for a national smoke-free law in China. Around the world, smoke-free laws have resulted in dramatic improvements to health. For example, Ireland's national smoke-free law led to a 26 percent decrease in deaths from heart disease, and a reduction in stroke deaths by almost one-third just three years after the law came into effect.

In China, more than a dozen cities across the country have adopted smoke-free laws, but many of these laws are not nearly as effective as they could be: because of weaknesses in the laws themselves - for instance, loopholes that allow smoking in some indoor public places - and a lack of sufficient enforcement. Where this is the case, exposure to secondhand smoke remains high.

However, Beijing's new smoke-free law is a game changer. The capital now requires all indoor public places to be 100 percent smoke free, without exception. The Beijing law is fully compliant with Article 8 of the World Health Organization's Framework Convention on Tobacco Control, and as such sets a new high-water mark for smoke-free laws in China.

It is now time to extend the benefits of clean air and protection from exposure to secondhand smoke to everyone in China.

The data presented in our new report show smoke-free laws are extremely popular with Chinese people, even smokers. Public support for a national law is therefore likely to be very strong. Smoke-free laws are also good for the economy, because they help to create a healthier workforce and reduce the financial burden of tobacco-related illness on businesses.

Right now, China stands on the cusp of a quantum leap forward on tobacco control. Three-quarters of a billion nonsmokers are forced to inhale toxic tobacco smoke every day. Each day, hundreds die as a result. Exposure to secondhand smoke is deadly - but unlike other dreadful diseases that claim thousands of lives, we have a cure: making all indoor public places 100 percent smoke-free. Beijing has shown us how it can be done. It is now time for national action, and the adoption of a national smoke-free law that will give the gift of clean indoor air to all of Chinese people.

Bernhard Schwartlander is WHO representative in China, and Geoffrey T. Fong is chief principal investigator of the International Tobacco Control Policy Evaluation Project at the University of Waterloo. The views do not necessarily reflect those of China Daily.