On the afternoon of March 11, a parent and child were playing table tennis on the roof of a building of Wuyang new town in Guangzhou, while an aunt was playing basketball on the opposite roof. After the outbreak of COVID-19 in January 2020, Chinese citizens followed the government’s advice，stayed at home and reduced the chance of cross infection. As a result, the rooftop of residential buildings, which used to be used only for drying clothes and quilts, had become the best exercise ground for the elderly and children.