Hong Kong labour authorities have unveiled changes to the system that sends out warnings to workers about overexertion during very hot weather, reducing thresholds so higher-tier alerts can be issued more easily following intense criticism of the mechanism.The Labour Department said on Thursday that two new conditions would be introduced to the Heat Stress at Work Warning system from Friday.The system has three warning levels – amber, red and black – which alert employers and staff to the severity of heat stress if they are working outdoors or indoors without air conditioning.The first change will reduce the threshold for triggering a higher-tier warning if the Observatory has already issued the extremely hot weather special alert, to ensure a quicker response.The second change will see the warning automatically be raised by one level – from amber to red, or from red to black – when the measured temperatures generally over Hong Kong reach 35 degrees Celsius (95 Fahrenheit) or above.Commissioner for Labour Sam Hui says the revamped system will better protect workers during periods of abnormally high temperatures. Photo: Elson LiThe revamp was introduced after the system faced criticism over the lack of higher alerts earlier this month, when the city was grappling with record-breaking temperatures.