Pupils in Zaozhuang city, East China`s Shandong province, collect cigarette butts on May 30, 2011, to add to a warning board reading "cancer" in Chinese, to call for people to quit smoking. The activity was held to commemorate World No-Tobacco Day, which falls on May 31. [Photo/Xinhua]

Students from Xiaoxiang Primary School in Yantai city, East China`s Shandong province, sign their name on May 30, 2011, on a huge cigarette model, which reads "No tobacco, cherish the life", to welcome the upcoming World No-Tobacco Day on May 31.[Photo/Xinhua]

Students from Xiaoxiang Primary School in Yantai city, East China`s Shandong province, lift a banner on May 30, reading "Welcome World No-Tobacco Day on May 31", as well as six posters warning in Chinese, "Smoking is harmful to health".[Photo/Xinhua]