The Centre for Health Protection of the Department of Health had earlier conducted epidemiological investigations of the three cases of COVID-19 in Heng Tai House, Fu Heng Estate in Tai Po, which covered the environmental samples collected from various locations at Heng Tai House. The Government today (March 17) released the test results of the environmental samples. Among the 12 samples collected from the two relevant units of the confirmed cases and the rooftop, four of them were tested positive. Two samples are collected near the water closet of the confirmed case's unit on the 32nd floor; a sample near the water closet of the confirmed case's unit on the 34th floor; and another inside the open end of the rooftop ventilating pipe of the foul water stack of Unit 13.
The Development Bureau, the Environment Bureau, the Food and Health Bureau, the Transport and Housing Bureau, the Buildings Department, the Environmental Protection Department, the Department of Health and the Housing Department convened an interdepartmental meeting this morning to examine the test results.
A Government spokesman said, "the building, drainage system and ventilating pipe designs of Heng Tai House comply with the requirements of the Buildings Ordinance (Cap. 123), related regulations as well as environmental and health safety standards. According to the preliminary analysis, the virus found near the water closets inside the units of confirmed cases is very likely to be remained after the patients using the toilet. With regard to the virus found inside the rooftop ventilating pipe of the foul water stack, it is suspected that the height difference between the rooftop parapet of Unit 13 and Unit 14 might be relatively conducive to cause wake effect in the re-entrant of top floors in Heng Tai House. However, the combination of various environmental factors, including building orientation, roof design, wind speed and direction, etc. is essential in bringing the virus into residential units from the rooftop ventilating pipe of the foul water stack by air turbulence. Even if the wake effect might have occurred, the relevant Government departments considered the circumstances as isolated case and is uncommon.
"For safety sake, the Government will set up an inter-departmental expert group as soon as possible to follow up the above issue. The Government will inspect and collect information of the relevant ventilating pipes of the buildings where confirmed cases were recorded earlier, the current situation of their nearby environment as well as any other relevant information to facilitate the expert group's further investigation and examination. The expert group will also make improvement recommendations and measures in accordance with the investigation results to safeguard public health."
The inter-departmental expert group comprises representatives of the Development Bureau, the Environment Bureau, the Food and Health Bureau, the Transport and Housing Bureau, the Architectural Services Department, the Buildings Department, the Drainage Services Department, the Electrical and Mechanical Services Department, the Environmental Protection Department, the Food and Environmental Hygiene Department, the Department of Health, the Housing Department, and the Water Supplies Department.
The Government advises members of the public to maintain drainage pipes properly and regularly pour about half a litre of water into each drain outlet (U-traps) to ensure environmental hygiene. After using the toilet, they are advised to put the toilet lid down before flushing to avoid spreading germs. If residents of units on top floors notice faeces odour from time to time and there are confirmed cases at their building, they should close the windows of the relevant rooms. They may also put disinfection tablets into flushing water cistern of the water closet to keep foul water stack clean. When they go to rooftop, they should wear masks and avoid approaching near or touching the open end of the rooftop ventilating pipe of the foul water stack.
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