To mark this year's World No Tobacco Day, the Bill & Melinda Gates Foundation has launched the first-ever anti-smoking social media campaign in China to raise public awareness, particularly of secondhand smoking.

The online campaign, "Say No to Forced Smoking", will enroll more than 1,000 volunteers across the mainland, including some celebrities, to upload their anti-smoking photos to social networking sites such as Sina Weibo.

Official estimations suggest nearly 740 million people suffer from secondhand smoke on the Chinese mainland.