Visitors look at toilet air purifiers which are capable of odour analysis and deodorization at the 2018 Chinese Toilet Revolution Innovation Expo in east China's Shanghai, Nov. 18, 2018. The three-day expo opened at Shanghai Everbright Convention & Exhibition Center on Sunday. The event showcases materials, products and designs for major fields of the toilet industry, including smart toilets, rural toilets, toilets in tourist areas and toilet facilities for commercial use. (Xinhua/Fang Zhe)