Subways sparkle, but does cleaning decrease COVID-19 risk?

Mass transit systems around the world have taken unprecedented — and expensive — steps to curb the spread of the coronavirus, including New York shutting down its subways overnight and testing powerful ultraviolet lamps to disinfect seats, poles and floors.The Moscow Metro and a public bus company in Shanghai have experimented with germ-killing ultraviolet light.The public transit system in Dallas tested a “dry fogging” system, and Hong Kong used a robot that sprays a hyd