Ex-Observatory chief slams ‘decorative’ heat stress warning system after record temp. only triggers lowest alert

Former Hong Kong Observatory chief Lam Chiu-ying has criticized the government's heat stress warning system for issuing only a low-level alert during Sunday's record-breaking temperatures. Lam, who led the Observatory from 2003 to 2009, found it "truly baffling" that temperatures over the weekend only triggered the "Amber" Heat Stress At Work Warning.

The system, which consists of amber, red, and black alerts, has only seen the amber level triggered more than 200 times since its introduction in May 2023, while the red and black levels have never been activated. Lam questioned the system's effectiveness, asking, "Isn't that a bit strange?" He pointed out that the Amber Heat Stress At Work Warning is triggered at a reading of 30 on the Hong Kong Heat Index, while a red or black warning requires the index to reach 32 and 34, respectively.

The warning system, which takes humidity, wind speed, and solar radiation into account, has been criticized for underestimating the impact of direct solar radiation on outdoor workers. Lam suggested that the government consider adopting the Wet Bulb Globe Temperature (WBGT), a different heat reading that gives more weight to solar radiation, as a more accurate indicator.

Fay Siu, from the Association for the Rights of Industrial Accident Victims, also supported this idea, noting that the WBGT had reached the "red" warning level on several days recently, compared to the local index.