Scientists who initially warned about contaminated surfaces now say that the virus spreads primarily through inhaled droplets, and that there is little to no evidence that deep cleaning mitigates the threat indoors. HONG KONG — At Hong Kong’s deserted airport, cleaning crews constantly spray baggage trolleys, elevator buttons and check-in counters with antimicrobial solutions. In New York City, workers continually disinfect surfaces on buses and subways. In London, many pubs spent lots of money on intensive surface cleaning to reopen after lockdown — before closing again in November. All over the world, workers are soaping, wiping and fumigating surfaces with an urgent sense of purpose: to fight the coronavirus. But scientists increasingly say that there is little to no evidence that contaminated surfaces can spread the virus. In crowded indoor spaces like airports, they say, the virus that is exhaled by infected people and that lingers in the air is a much greater threat.