Ex-Observatory chief slams 'decorative' heat stress warning system after record temps

A former head of the Hong Kong Observatory has sharply criticized the government's heat stress warning system, calling it "decorative" after it failed to issue higher alerts during a recent record-breaking heatwave.

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Isn’t that a bit strange?

Lam Chiu-ying, who led the Observatory from 2003 to 2009, expressed bafflement that the "Amber" Heat Stress At Work Warning was the highest alert triggered, despite temperatures soaring. Reports indicate the amber warning has been activated over 200 times since its 2023 introduction, while the more severe "Red" and "Black" warnings have never been used.

Temperatures reached 39.8 degrees Celsius in Sheung Shui on Sunday, with the Observatory headquarters recording 36.9 degrees Celsius, as a heatwave influenced by Tropical Cyclone Dolphin persisted. The warning system recommends different rest arrangements for outdoor workers or those without air conditioning, but these recommendations are not legally binding for employers.

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If even record-breaking temperatures fail to trigger [the red warning], is it not just a decorative display piece?

Lam questioned the system's effectiveness, particularly its reliance on the Hong Kong Heat Index. He argued that the index underestimates the impact of direct solar radiation, which is crucial for outdoor workers, due to its low weighting for this factor. The index primarily uses the Natural Wet-Bulb Temperature, which measures evaporative cooling, accounting for 80% of the figure, as heat-related hospitalizations are often linked to impeded sweat evaporation. The Black Globe Temperature, measuring radiant solar heat, has a minor correlation with hospitalizations and constitutes only 5% of the index.

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The solar radiation weighting within the Hong Kong Heat Index is very low, making it unsuitable for outdoor work environments.