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Following is the question by the Hon Choy So-yuk and a reply by the Secretary for Economic Development and Labour, Mr Stephen Ip, in the Legislative Council today (June 13):
Question:
It has been reported that, after consolidating the statistics from 1983 to 2005 on mortality rate, temperature, humidity, wind speed and the heat of the sun, the Hong Kong Observatory ("HKO") has found that whenever the heat stress index ("HSI") moved up one level in summer, the mortality rate would increase by twofold, and in winter, whenever the HSI moved down one level, mortality rate would increase by 130%. As such, HKO is considering announcing the HSI on a daily basis from 2009 onwards. In this connection, will the Government inform this Council:
(a) of the details of the HSI from 1983 to 2005; and
(b) whether it will, besides alerting the public by announcing the HSI when it reaches a dangerous level, consider putting in place complementary measures with binding effect to safeguard public health; if it will, of the details?
Reply:
Madam President,
The Hong Kong Observatory (HKO) has carried out studies on thermal stress indices since the late 1990s. Such studies help HKO to issue cold and very hot weather warnings to alert the public on the need to take necessary precautions to cope with extreme temperatures and to facilitate Government departments and non-governmental organisations (NGOs) in providing appropriate support services to those in need.
Apart from temperature, the comfort of human beings is affected by other weather parameters such as humidity and wind speed and such effects are usually quantified through thermal stress indices. Over 100 thermal stress indices have so far been recorded. In its latest study, HKO employs a thermal stress index called the Net Effective Temperature (NET) to study the recent climate change and the possible relationship between NET and mortality. NET reflects the common perception that people tend to feel more stressful on hot and humid days without wind in summer, and cold, humid and windy days in winter.
My answer to the two parts of the Hon Choy So-yuk's question is as follows:
(a) Details of the mean daily maximum NET in summer and the mean daily minimum NET in winter from 1983 to 2005 are in the Annex. Generally speaking, the mean daily maximum NET in Hong Kong in summer (May - September) increased at a rate of 0.15 per decade in this period. In winter (November - March), the mean daily minimum NET in Hong Kong increased at a rate of 1.15 per decade in the same period.
(b) Currently, the cold and very hot warnings issued by HKO effectively alert the public on the need to take necessary precautions to cope with extreme temperatures. Government departments and NGOs also provide necessary support to those in need in the event of such warnings. For instance, the Home Affairs Department provides temporary shelters to people in need in the event of cold or very hot weather.
The research work of HKO on thermal indices is ongoing. HKO will also make reference to the Guideline on Universal Thermal Climate Index by the World Meteorological Organisation (WMO) planned to be released in 2009. The existing cold and very hot warnings have served us well and further studies will be required before we can determine whether there is a need to introduce a thermal stress index for public dissemination.
Ends/Wednesday, June 13, 2007
Issued at HKT 15:16
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