As China grapples with the spread of the deadly coronavirus, drone maker DJI has been helping disinfect the streets. The company’s volunteers aim to cover 3 million square meters (1.15 square miles) in just four days, according to local media. The spraying will take place from Friday to Monday in the southern city of Shenzhen, where DJI’s headquarters are located. It will cover factories, residential areas, hospitals and waste treatment plants.

Over the past few weeks, local governments and agricultural drone owners have been utilizing drones to spray disinfectant, but they’ve also found other new uses. Some are using drones to disperse public gatherings and issue warnings over speakers. Drones also helped out with building additional hospital capacity in Wuhan, the epicenter of the outbreak, by providing lighting as construction workers rushed to complete the urgently needed facilities.

Not everyone agrees that spraying disinfectant all over cities is a good way to stop the virus, which has already taken more than 900 lives and infected tens of thousands. Public health experts cited by Business Insider said that citywide germ busting is likely ineffective, suggesting disinfection efforts should focus on emergency rooms and other hospital areas.