The Novel Coronavirus Response and Coordination Centre states that COVID-19 is mainly spread by droplets between people in close contact, by aerosol (such as tiny droplets produced during talking or coughing, or polluted particles raised by fan which can be suspended in air for a long time; a person can be infected in prolonged exposure to a high concentration of aerosol) between people staying in a confined or semi-confined space for a long time, or via indirect contact with surfaces of environment or objects.
The Centre points out that, based on past experience, the vast majority of cases occurred among close contacts, namely living together, eating and drinking in the same space, and having activities in the same space without wearing a mask, and there were cases found to have gathered together in the same building. In some buildings, there was a phenomenon that more cases were detected on the same floor or in the same orientation; however, there is no significant evidence that these cases were being infected via patios or pipes. For the above, as a precautionary measure, members of the public are advised to take the following measures to reduce the spread of COVID-19 in the building:
1. A mask must be put on when leaving your own unit, even for short-term behaviour like dumping garbage, especially when a case has been detected in the building;
2. Avoid touching the surfaces of common areas in the building, such as elevator buttons, doorknobs, handrails, etc. Perform hand hygiene immediately after touching them, and do not touch your eyes, nose or mouth before washing your hands;
3. Do not enter the elevator when there are many people inside; wear a mask properly when sharing the elevator with others;
4. Pour water to the ground drain every day to prevent the U-shaped pipe from drying up;
5. Maintain good indoor air ventilation. Fresh air in the unit should be supplemented through doors and windows facing open areas, instead of via patios or doors facing other units. For example, doors and windows facing patios or other units should be closed, where air exhausts facing patios should be turned on, and doors and windows facing the open space should be opened;
6. If an air extraction device for common exhaust pipe of the building is used without a backflow prevention device, keep the air extraction device turned on to prevent air from other units flowing into the unit;
7. When the exhaust fan in a small space like kitchen and toilets is turned on, and no window shutter is in place, half-open the door and window that do not face the patio, so that there is air convection and avoid negative pressure to the drain.