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

A former Hong Kong Observatory chief has criticised the government's heat stress warning system for only issuing a low-level alert during the city's recent heatwave. Lam Chiu-ying, who led the Observatory from 2003 to 2009, said it "truly baffling" that the system only triggered the "Amber" Heat Stress At Work Warning during a weekend of record-breaking temperatures.

The mercury reached 39.8 degrees Celsius in Sheung Shui on Sunday, while the Observatory's own headquarters recorded a temperature of 36.9 degrees Celsius. The Heat Stress Warning system consists of amber, red and black alerts, which recommend different rest arrangements for employees working outdoors or without air conditioning.

None of these warnings are legally binding for employers. The red and black warnings would trigger work suspensions for workers with heavy physical workloads, but have never been activated. Lam pointed out that the system appears to be more of a "decorative display piece" if it cannot even trigger for extreme temperatures. The warning system takes into account factors such as humidity, wind speed, and solar radiation to calculate the Hong Kong Heat Index.

However, Lam argued that the index underestimates the heat stress effects of direct solar radiation, particularly for outdoor workers. He suggested the government adopt the Wet Bulb Globe Temperature (WBGT) instead, which gives more weight to the Black Globe Temperature that measures radiant solar heat.