Qingdao has rolled out electronic mask vending machines in the city's subway stations.Besides Qingdao, other cities in China including Beijing, Wuhan, Tianjin, and Wuxi have also equipped some of their subway stations with mask vending machines.This comes as masks have become a necessity for daily travel in the cities, where residents are not allowed to ride public transport without one to curb the spread of COVID-19. The move has been welcomed by metro riders.The machines have surgical masks and KN95 masks. Customers just need to select the masks they want and then scan the code to pay for them before they can pick up the goods.