A recent study by City University of Hong Kong found that closing the toilet lids before flushing was not effective enough in cutting the spread of Coronavirus, but suggested people to keep their toilet ventilation fan operating for a long time. Dr. Alvin Lai, Deputy Dean of CityU’s Department of Architecture and Civil Engineering said, even if you closed the toilet lid, there would still be the tiniest virus going through the slightest gap, forming highly contagious aerosol in the air. However, in an ideal lab environment, 15-minute of ventilation fan operation is able to reduce at least 87% aerosol. While it lasts for 30 minutes, the reduction goes up to 98%. He also suggested citizens to clean closestool with bleaching water regularly.