2 more ex-Observatory directors urge gov’t to revamp heat stress index for outdoor workers amid controversy

Two more ex-Hong Kong Observatory (HKO) directors have urged the Labour Department to revamp a controversial heat stress warning for outdoor workers, after even record high temperatures triggered only the lowest alert.

Lee Boon-ying and Shun Chi-ming, both former directors of the HKO, said in a jointly written op-ed in Ming Pao on Thursday that the Labour Department’s Heat Stress at Work Warning uses an incorrect heat stress reference, causing a delay in issuing warning signals.

The two former Hong Kong officials said they “sincerely hope” the Labour Department will listen to the public and adjust the warning system.

“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,” the op-ed reads.

“[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 warning system sparked controversy earlier this week after the alert remained at amber – the lowest warning – even as the city experienced its hottest day in 143 years on Sunday.

The HKO recorded a temperature of 36.9 degrees Celsius at its Tsim Sha Tsui headquarters and a temperature of 38.9 degrees Celsius in Sheung Shui that day.

On Tuesday, the Labour Department said it would revamp the system amid the controversy. The day before, Lam Chiu-ying, also a former HKO director, called the system “decorative.”

Based on incorrect reference of heat

The Labour Department introduced the three-tier Heat Stress at Work Warning, a system designed to help protect Hong Kong workers from heatstroke, in May 2023. The system consists of three levels of warning: amber, red and black.

Employers are advised to allow longer breaks for outdoor workers or those working in indoor environments without air conditioning if the Labour Department issues warnings under the system.

Lee and Shun said in the Ming Pao op-ed that the system is based on the HKO’s Heat Index (HI). HI assesses the combined health impacts of heat stress caused by high temperature, high humidity, light wind, and intense sunlight.

HI is a standard of reference for the general public, who might likely be indoors in an air-conditioned environment, the two former officials said, adding that it is not meant for people working outdoors.

Lee and Shun also said that under the Heat Stress at Work Warning system, the Labour Department will consider issuing the amber warning signal when HI reaches 30.

However, according to a joint study by the HKO and the Chinese University of Hong Kong, the number of hospitalisations starts to rise quickly when the HI reaches 30.

“Moreover, issuing and delivering warnings takes time, leading to a lag that prevents outdoor workers from taking timely precautions. Due to this insufficient protection, the practice of issuing warnings fails to reassure people,” Lee and Shun said.

The officials urged the Labour Department to revamp the Heat Stress at Work Warning and base it on the “wet-bulb globe temperature (WBGT),” another index introduced by the HKO in 2008.

The two weather experts said the WBGT is a more accurate index for reflecting the heat stress that outdoor workers face.

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Irene Chan is a reporter at Hong Kong Free Press and has an interest in covering political and social change. She previously worked at Initium Media as chief editor for Hong Kong news and was a community organiser at the Society for Community Organisation serving the underprivileged. She has a bachelor’s degree in Journalism from Fudan University and a master’s degree in social work from the Chinese University of Hong Kong.

Irene is the recipient of two Society of Publishers in Asia (SOPA) awards and three honourable mentions for her investigative, feature and video reporting. She also received a Human Rights Press Award for multimedia reporting and an honourable mention for feature writing.