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 second-hand smoke of others. Many countries have now moved to fix this problem, in light of the unequivocal scientific evidence of the harms caused by exposure to tobacco smoke.

Yet in China, close to 740 million people - including 182 million children - are exposed to second-hand 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 second-hand smoke in the world. An estimated 100,000 people die every year in China because of second-hand 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 second-hand smoke: there is no safe level. Every time you breathe in second-hand smoke you are inhaling 7,000 chemicals and 69 known carcinogens, and risking lung cancer, heart disease and strokes. In babies and children, second-hand smoke can cause sudden infant death syndrome, low birth weight, respiratory problems and ear infections.