Ex-Observatory chiefs unite in push for WBGT heat warnings for outdoor workers

Two more former Observatory directors have joined calls to overhaul the city's heat stress warning system for outdoor workers, urging a switch to the internationally recognized Wet Bulb Globe Temperature (WBGT).

The appeal came after the recent record-breaking heat triggered only the lowest alert, sparking public criticism over the system's effectiveness in reflecting risks for outdoor workers.

Writing to a newspaper on Thursday, former directors Shun Chi-ming and Lee Boon-ying called the use of the Observatory's Hong Kong Heat Index (HKHI) a "mismatch" for the Heat Stress at Work Warning, as it targets the general public rather than outdoor workers.

The pair criticized the high threshold for the warning, noting that the yellow warning during the city's record heat exposed the system's inadequacy that left workers unprotected.

They pointed out that the Labour Department only considers issuing a warning when the HKHI hits 30, whereas hospital admission rates already accelerate — a delay that puts workers at risk.

As for WBGT— a system that has proven effective globally by factoring in humidity, wind speed, and radiant heat — they believed the switch would only do good and no harm.

Highlighting that extreme heat has become the city's deadliest weather phenomenon that claimed more lives than typhoons and heavy rain, they urged the department to make a change based on scientific evidence.

Meanwhile, former Observatory director Lam Chiu-ying updated on social media this morning that at least nine of the Observatory's 10 monitoring stations recorded WBGT exceeding 32 degrees from last Friday to Sunday, which should have triggered a Red Heat Stress at Work Warning last week.

Notably, four stations even recorded 34 degrees last Saturday, which Lam said has reached the black warning level.

𝗗𝗼𝘄𝗻𝗹𝗼𝗮𝗱 𝗧𝗵𝗲 𝗦𝘁𝗮𝗻𝗱𝗮𝗿𝗱 𝗔𝗽𝗽 ↓