Hong Kong enhances heat stress warning system after chorus of criticism, but rules still not binding

The Hong Kong Labour Department has updated its Heat Stress at Work Warning (HSWW) system in response to criticism that previous thresholds failed to alert workers during record-breaking temperatures. Two new trigger conditions will be implemented starting Friday to better protect workers in high-temperature environments. When a special "Extremely Hot Weather" alert is issued by the Hong Kong Observatory, the system will lower the monitoring threshold for higher-level warnings, raising the level from amber to red or red to black.

However, the new rules are not yet mandatory for employers. This comes after the HSWW system faced criticism for not issuing alerts during the city's hottest day in 143 years on August 9. Former Hong Kong Observatory directors have called for the system to be revamped, suggesting the adoption of the wet-bulb globe temperature, an internationally recognized measure of environmental heat that considers humidity, heat radiation, and air movement.

Despite not adopting this suggestion, the department acknowledges it will consider it in the future. A local charity supporting workplace accident victims believes the lowered thresholds will improve the system's sensitivity and support a government mandate for work stoppages during black heat stress warnings, as well as more frequent rest breaks during lower warning levels.