Summer Occupational Safety and Health - Prevention of Heat Stroke at Work

Hong Kong's long, hot and humid summers hold many hazards, but sensible precautions help everyone to stay healthy and safe.

Heat stroke poses a real risk for manual workers and others if they do not take appropriate preventive measures. Employers and employees alike should be aware of the potential dangers for anyone working in a hot environment. They should learn what preventive measures to take.

Manual workers are not the only people who risk heat stroke at this time of year, although they are certainly the most obvious, especially if they work outdoors under the sun. People who work in kitchens and laundries are equally at risk by the nature of their jobs and working environment.

How does the body regulate the temperature?
A stable internal body temperature requires a balance between heat production and heat loss. Metabolism, physical activity and external heat absorption are the major heat sources of our bodies. More heat is absorbed into the body when the radiant temperature of the surroundings is high, e.g. direct exposure to sunlight or a heat source like a stove. Heat is mainly lost through sweat evaporation, a natural cooling mechanism which decreases as humidity increases. Air movement facilitates, but unsuitable clothing hampers heat loss. Heat accumulates in our body when heat production is greater than heat loss, e.g. performing strenuous physical work in a hot, humid and stuffy working environment, causing heat-related illnesses.

People who are new to working in hot conditions need a few weeks to adapt themselves completely to the environment: that is a process of acclimatization. During this period, they are particularly prone to heat-related illnesses.

What are heat-related illnesses?
Heat-related illnesses come in different severity, from the milder heat cramps and skin disorders to the serious heat exhaustion and heat syncope and, lastly, to the life-threatening heat stroke.

What is heat stroke?
Heat stroke occurs when the body fails to regulate its core temperature. Heat stroke is very serious and can be life threatening if it is not treated urgently.

Initially, the sufferer has fatigue, thirst, nausea, headache and clammy skin. Later, the sufferer stops sweating and the skin becomes hot and dry. The body temperature rises, with the core body temperature higher than 41 degrees. The sufferer may be confused and even lose consciousness. Pale colour, weak and rapid pulse and also convulsion are all indications of heat stroke.

First Aid Treatment for heat stroke
Heat stroke requires urgent medical treatment by a doctor. Until a doctor can be reached, first aid measures should be taken to cool the sufferer as fast as possible by soaking the victim's clothing in cold water and giving cool fluids if the person is conscious. At the same time, increase air movement by fanning the sufferer.

Prevention of heat stroke - good business sense
Every good employer will be concerned to ensure the safety and good health of workers. And it also makes good business sense to control the occupational hazards in a hot environment. It benefits the employer if occupational injuries and adverse effects on the health of workers can be reduced. If working conditions are improved, employees will be noticeably more enthusiastic and better motivated. Productivity and working efficiency improve and there is a noticeable drop in absenteeism. Candid and sincere dialogue between employers and employees can go a long way towards ensuring occupational safety and health and benefit both parties in a classic win-win situation.

Supervisors and workers should be trained to recognise the early symptoms of heat stroke so that they can take effective action before the situation becomes serious.

Prevention is Better than Cure
The Occupational Safety and Health Ordinance (Cap 509) sets out the general duties of employers. Specifically, they must, so far as reasonably practicable, ensure the safety and health of all their employees. In respect of the prevention of heat stroke, it is therefore the legal responsibility of employers to assess such risks for their employees working in a hot environment and take appropriate preventive measures.

Heat stroke can be caused by a variety of reasons. Sole reliance on weather conditions is therefore inappropriate for assessing the risk of heat stroke. Rather, all factors should be taken into account, including environmental factors such as the temperature, humidity and wind speed in the workplace, and the precise nature of work as well as individual factors such as the health condition of workers, the effects of drugs being taken and the clothing worn by them.

Employers should devise a safe and healthy work system to safeguard their employees against heat stroke. Among other things they should ensure that the work environment isolates heat generating facilities and they should use insulating materials to minimize heat dissipation into other work areas. They should also increase air flow by installing suitable ventilation, fans or air conditioning system as appropriate, especially in workplaces like kitchens and containers. If it is unavoidable to have work carried out under direct sunlight, temporary sunshades should be set up wherever possible.

If possible, schedule work to avoid the hottest periods of the day. Organise the project to avoid prolonged periods of time working in a hot environment. Be aware of weather forecasts and hot weather warnings. Plan work as far as possible to take place in the early morning or late in the day and in cooler, shaded areas whenever this is feasible. Physical demands on workers can be limited by the use of appropriate mechanical aids. Arrange for employees to rest regularly in a cool, shady place during very hot spells. Allow employees to take regular breaks or rotate tasks with other workers within the shift to reduce prolonged exposure to hot conditions.

Always ensure that cool drinking water is available for employees at all times during working hours. Encourage employees to drink plenty of water or other appropriate beverages to replenish the fluid and electrolytes lost through sweating.

Clothing
Suitable clothing is essential. Light-coloured clothing minimizes heat absorption and improves heat dissipation. Loose fitting clothing enhances the evaporation of sweat, although clothing that is too loose has its own hazards as care must be taken to prevent it from becoming entangled in the moving parts of machines. When selecting uniforms, bear in mind that natural materials enhance heat dissipation better than synthetics.

Ensure that the face, neck and back are shaded from direct sunlight by the broad brim of a helmet or wide-brimmed hat.

Health
Pay special attention to any report of employees suffering from symptoms of heat stroke. Employees should be trained to observe their own body responses. Whenever they become aware of any symptoms of heat stroke, they should inform their supervisors and take appropriate action immediately.

Some employees may find it difficult to adapt to the hot working environment because of their health condition or the effects of drugs. Employers should take such factors into account and consider recommending such employees to attend a doctor when work in hot conditions is assigned to them.

Promotion and Education
The Labour Department (LD) has published a leaflet on "Prevention of Heat Stroke at Work in a Hot Environment" for employers and employees. We also organize free occupational health talks in public places and in our Occupational Safety and Health Centre every month to raise employers' and employees' awareness of occupational health. Please refer to the details for the occupational health talks on the prevention of heat stroke at work at http://www.labour.gov.hk/eng/osh/content11.htm.

Moreover, LD also provides out-reaching health education service and occupational health nurses will disseminate occupational health information at your workplace at a time convenient to you. Please contact the nursing officer at 2852 4062 for details.