Piles of tiles: Two workers examine tiles at a workshop of the Monalisa Ceramics Company in Yuantan township, in Guangdong’s Qingyuan county, on Oct. 28. The facility was recently relocated from Foshan and is one of many highly polluting ceramics factories that have been moved in an effort to improve air, water, and soil quality. China is the world’s largest producer of ceramic tiles, and output has increased 20 percent annually during the past decade. The government has been tightening environmental controls, however, which could slow the industry’s growth.