Ex-Observatory chiefs urge revamp of Hong Kong heat stress index for outdoor workers

Two former directors of the Hong Kong Observatory have joined calls for the Labour Department to overhaul a controversial heat stress warning system for outdoor workers. Lee Boon-ying and Shun Chi-ming argue the current system uses an incorrect heat stress reference, leading to delayed warnings even during extreme heat.

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Extreme heat is the biggest ‘weather killer’ in Hong Kong, claiming more lives than severe weather events such as typhoons, rainstorms, and thunderstorms. With global warming, record-breaking temperatures and heat waves will only become more frequent, causing even more casualties.

In a joint op-ed, they emphasized that "extreme heat is the biggest 'weather killer' in Hong Kong," surpassing typhoons and storms. With global warming increasing the frequency of record temperatures and heat waves, they fear more casualties. They "sincerely hope" the Labour Department will heed public and expert advice to adjust the warning system based on scientific principles.

The controversy erupted earlier this week when the alert remained at amber, the lowest level, despite temperatures reaching 36.9 degrees Celsius (98.4 Fahrenheit) at the Observatory headquarters and 38.9 degrees Celsius (102 Fahrenheit) in Sheung Shui on Sunday, the hottest day in 143 years. The Labour Department announced Tuesday it would revamp the system amid public outcry. Another former director, Lam Chiu-ying, had previously called the system "decorative."

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We sincerely urge the Labour Department to listen to the public, community groups, and experts, and to act on good advice by making scientifically sound adjustments to the Heat Stress at Work Warning and therefore benefit citizens affected by extreme weather.

The Heat Stress at Work Warning system, introduced in May 2023, has three levels: amber, red, and black. Employers are advised to provide longer breaks for outdoor workers or those in non-air-conditioned environments when warnings are issued. Lee and Shun explained that the system relies on the Observatory's Heat Index (HI), which considers temperature, humidity, wind, and sunlight. However, they contend that HI is suitable for the general public, who are often indoors, and not for outdoor workers. The Labour Department currently considers issuing an amber warning when HI reaches 30.

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decorative