Such was the conclusion by the report compiled jointly by the Hong Kong Special Administrative Region (HKSAR) Department of Health and other government agencies on the outbreak of SARS, that occurred among residents of Amoy Gardens in Kowloon Bay in Kowloon towards the end of March 2003.

The report, which was made public Thursday, is the result of a detailed investigation covering epidemiological, environmental public hygiene, building design and utilities considerations of the housing estate.

However, tiny water droplets containing viruses from the contaminated sewage of the bathroom floor drains and dried-up U-trap of the toilet bowl were found to provide a pathway through which the residents came into contact with the small droplets, the report said.

"These droplets entered the bathroom floor drain through negative pressure generated by exhaust fans when the bathroom was being used with the door closed. Water vapor generated during a shower and the moist conditions of the bathroom could also have facilitated the formation of water droplets.

"Contaminated droplets could then have deposited virus on various surfaces, such as floor mats, towels, toiletries and other bathroom equipment," it said.

The report suggests that for the U-trap preventive mechanism to function properly, the water traps must be sufficiently filled with water all times, it said.

The HKSAR Food And Environmental Department has given advice to residents of various blocks in Amoy Gardens to disinfect their flats as precautionary measures, particularly sinks, bathtubs, wash hand basins, toilet bowls and floor drains in the toilets and kitchens, it said.

The administration has published a set of guidelines to draw the public's attention to the proper maintenance and repair of the drainage system and sanitary facilities.

(Xinhua News Agency April 18, 2003)