From Friday, Hong Kong will optimize its heat-stress warning system by lowering the trigger thresholds. Warnings under the new system will also go up one level if the temperature reaches 35 C or above across most of the city.
Authorities expect the revamp will result in four to seven Red Warnings — the second-highest signal — and one to two top-tier Black Warnings each year, promising to step up inspections and enforcement to protect workers from extreme heat.
Hong Kong withstood a historic heat wave early this month, when the Observatory on Aug 9 recorded 36.9 C, the city’s highest official temperature in 142 years. Yet, even the extreme temperature only triggered the lowest amber signal under the city’s three-tier Heat Stress at Work Warning system.
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Since the current heat warning system launched in 2023, no red or black warnings — signals under which employers are required to take measures to protect outdoor workers — have been issued. This sparked debate among residents, meteorological experts and labor groups on the system’s methodology.
At a media briefing on Thursday, Commissioner for Labour Sam Hui Chark-shum announced that the enhanced system will introduce two new conditions for triggering different levels of Heat Stress at Work Warning system.
First, when the “Extremely Hot Weather” Special Alert takes effect, an alert issued by the Hong Kong Observatory when the city’s temperatures generally reach 35 C, the monitoring threshold for issuing heat warnings will be lowered automatically, enabling the early activation of higher level warnings.
Second, when the measured temperatures generally over Hong Kong reach 35 C or above, the warning level will be automatically raised by one tier — for instance, from Amber Warning to Red Warning, or from Red Warning to Black Warning — to alert the public of heat-related health risks.
The enhancement of the system will not impose additional work for employers or employees, said the government.
Hui said the new mechanism is based on joint research with the Observatory and expert advice, and swift updates are crucial as hot weather may continue.
He promised that the authorities will monitor the new system's performance and gather feedback for further improvements.
Kevin Wong Chi-ching, the Labour Department’s senior occupational hygienist in charge of development issues, said the new system will not see frequent flip‑flopping between warning levels. Upgrades will be automatically triggered when at least 40 percent of the city’s monitoring stations record temperatures of 35 C or above. Any downgrading will require over 60 percent of stations to dip below 34.5 C, along with other professional data, he added.
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Ivanhoe Chang Chi-ho, the city’s deputy commissioner for labour overseeing occupational safety and health, said employers may face prosecution if they endanger the health of employees without providing suitable heatstroke prevention measures.
Officials advised employers to conduct heat‑stress risk assessments for employees working in hot environments, and, based on the assessment results and the heatstroke risks faced at different warning levels, to implement the prevention measures outlined in the department’s Guidance Notes on Prevention of Heat Stroke at Work. These include rescheduling working times, providing shade and ventilation, and reminding workers to drink water and rest.
Chang promised that his department will enhance inspections and enforcement actions targeting workplaces with a higher risk of heatstroke to safeguard the occupational safety and health of employees.
He said employees should monitor their physical condition and inform their employers if they feel unwell. If necessary, they can call the department’s complaint hotline at 2542 2172 or submit an online complaint form for assistance. Chang encouraged the public to report any violations through these channels.
Contact the writer at amberwu@chinadailyhk.com
