For heat warnings to work, Hong Kong must have one clear, integrated system
- On the hottest day of the year, three different warnings were in force, having come on at different times – an integrated system would more clearly communicate the risk
- Besides policy and supportive employers, public awareness and education is also important as temperatures continue to rise with climate change
Hong Kong’s new heating stress warning system for workers, introduced by the Labour Department last month, is a good start to the city’s management of health emergencies and disaster risks from climate change. This comes as research shows strong associations among temperature, morbidity and mortality in Hong Kong.
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But what should be tackled is how to integrate this new system with the Hong Kong Observatory’s existing hot-weather warnings to simplify the city’s health disaster warning system for heat risks. There have been successful examples in the use of typhoon and rainstorm warning systems for workers.
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Tier 1 is triggered by a heat index of 29.5 with Tier 2 warnings in place when the heat index hits 30.5. These thresholds are scientifically based – at 29.5, the excess hospitalisation ratio starts to pick up, increasing more rapidly after 30 and, by 30.5, reaches an alarming level.
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In contrast, the new three-tier Heat Stress at Work Warning has thresholds for amber, red and black set at heat index readings of 30, 32 and 34 – which look too conservative. This is particularly because outdoor workers are much more exposed to weather than the general population.
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