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Heat Stroke - New Guidance for 2023

In the current weather conditions and during the summer months ahead, University staff and contractors are strongly urged to adopt measures to eliminate or mitigate the risk of heat stroke. This is particularly important on construction sites, but others who are required to spend long periods of time in hot or humid environments for work purposes may also be at risk.


The early symptoms of heat stroke include feeling thirsty, fatigue, nausea and headache. Later, the sufferer may experience shortness of breath, rapid and weak pulse, paleness and clammy skin, dizziness, confusion or even loss of consciousness and convulsions.


Construction workers and cleansing workers are especially prone to heat stroke when working for long hours in such an environment, especially if appropriate preventive measures have not been taken. There has been a heat stroke fatality in a construction worker working at a University in Hong Kong.


New Arrangements

The Labour Department has in May 2023 introduced new arrangements for management of the risk of heat stress at work. This includes specific new requirements for employers:

  • To conduct a workplace heat stress risk assessment. Employers may appoint a person who is familiar with the working conditions of the workplace and has basic occupational safety and health knowledge about heat stress to conduct the risk assessment. As a consequence this assessment will need to use the form prescribed by the labour department and be undertaken by those familiar with the working conditions of those employees at risk of heat stress.

The risk assessment form can be found here (English) and here (traditional Chinese)

  • The Labour department and Hong Kong Observatory have introduced an amber/red/black warning system for heat stress similar in intent to the typhoon/severe rainstorm warning system. Employers have to make appropriate arrangements for the adjusted rest periods based on the level of physical exertion in work, preset control measures and other heat stress risk factors, etc., in the hour following the announcement of the Heat Stress at Work Warning and the hourly updates announcing the continued effectiveness of the warning.


See here for English version and here for traditional Chinese version of instructions on how to obtain these push notifications.


Further points to note

  1. The model used to determine the conditions under which to issue red/amber/black heat stress warning does not consider the situation of those undertaking heavy manual work. Employees who work in this way may be at risk of heat stress even if a formal heat stress warning has not been issued. Employers have a duty of care under CAP 509 to prevent heat stress under any circumstances.

  2. The consequences of a heat stress work injury will be more significant if an employer did not conduct a heat stress work assessment relevant to the injured employees situation and/or did not respond within an hour of a formal heat stress warning being issued.

  3. In general if at all possible employers should aim to reschedule work to avoid it being necessary to conduct activities with potentially high levels of heat stress during the hotter and more humid parts of the day ie when a heat stress warning is likely to be issued.

  4. More detailed guidance including measures to reduce the impact of heat stress can be found on the labour department website here and here for an English version and here and here for a traditional Chinese version. Posters covering particular types of outdoor work activity are available here and here.

Further Advice and Guidance

The Occupational Safety and Health Council has created a thematic web site on this issue. These resources are available in Chinese (中文) here and here.

Practical measures to reduce heat stress may include, but not be limited to,

Supply of cool potable water at readily accessible points;

Suitable clothing, such as wide-brimmed hats and clothing that is thin and air permeable.

Erection of sunshades at appropriate locations;

Provision of ventilation (eg. blowers), shower facilities and/or cooling devices (e.g. cooling fans with atomized water spray);

Arrangements for regular rest breaks or job rotation to reduce workers’ exposure to the hot environment. A rest time calculator is available here and (中文) here.


If you have concerns about the possibility of heat stroke during University activities, or require advice on conducting a risk assessment to reduce heat stress, please contact the Safety Office on 3917 2400.


Paul Hunt PhD.

Director of Safety

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