Heat Stress
Operations carried out in workplaces with conditions such as high air temperatures, radiant heat sources, high humidity, direct physical contact with hot objects, or strenuous physical activities have a high potential of inducing heat stress to those employees engaging in such operations.
Key factors affecting the amount of stress a worker faces while performing activities in a hot environment are: temperature, humidity, radiant heat and air velocity. Other attributes that may influence the level of heat stress the worker is exposed to include age, weight, fitness, medical condition and acclimatisation to the heat.
Types of Heat Stress
- Heat stroke is the most serious health problem associated with over exposure to heat or hot environment. It occurs as a result of the failure of the body’s internal mechanism to maintain and regulate its core temperature. The victim of a heat stroke should be provided with immediate treatment which includes moving the person to a cool area and soaking his/ her clothes with cool water. Inadequate or lack of prompt response may lead to brain damage or injury to other vital organ of the victims, fatality as a result of heat stroke is highly probable!
- Heat exhaustion occurs as a result of excessive fluid loss from the body during perspiration. This usually occurs when there is lack of fluid intake or salt or a combination of both.
- Other heat exposure related illnesses include heat cramps, fainting (heat syncope) and heat rashes.
Heat Stress Incidents in Singapore
Between January and May 2009, there have been 5 reported incidents of heat stroke in Singapore (Ministry of Manpower Statistics, www.mom.gov.sg, 24 September 2009). All 5 victims were found to be from the construction industry and the cause of the incidents was attributed to over exposure to heat from the sun. For workers who are exposed to heat repeatedly in their workplaces, a set of guidelines for the prevention of heat stress are outlined as follows:
Measures to Prevent Heat Stress
Engineering measures – includes general ventilation and spot cooling using local exhaust ventilation (LEV) systems in areas with high heat production. Mechanical refrigeration, evaporative cooling, mechanical ventilation and adequate shelters for resting are some of the engineering control measures that may be adopted in order to minimize the workers’ exposure to excessive heat.
Administrative measures – Increase awareness in the workplace to workers on the importance of hydrating themselves with fluids periodically to reduce the likelihood of heat related stress (e.g. one glass or more of water every 15 to 20 minutes of work under hot conditions). Employers should factor in the workers’ physical conditions prior to assigning them to work in a high heat environment. Older workers, obese workers and personnel with previous medical conditions are at greater risk to acquiring heat disorders and hence should not be allowed to work in a hot environment. A pre-employment medical check-up should be conducted by the employer to verify the physical health status of the workers.
Acclimatisation of the workers should be taken into account, especially for those who just returned from a holiday break of more than a week, workers who are from countries with colder climate or workers returning to work after a long period of illness. Alternating work and rest periods along with rotation of duty among workers can help to avoid exposure to excessive heat (e.g. 5 minutes rest for every 25 minutes of manual labour under moderately hot conditions). Where feasible/ practical, heavy-manual labour should be scheduled during the cooler parts of the day (e.g. before 11am and after 3pm). Supervisors should be trained to detect early signs of heat stress and take necessary actions to prevent heat exhaustion or heat stroke incidents.
Personal protective equipment – provisions should be made for light-coloured, loosely-fitted clothing with minimal skin exposure to the sun. This is to minimise the potential of excessive perspiration or dehydration of the body as well as minimising the possibility of skin cancer due to over exposure to the sun.
By Sruti Balakrishnalal
Senior Consultant (PSB Academy)
References
Dr. Kenneth Choy, Prevention of Heat Stroke, Ministry of Manpower Singapore, viewed on 24 September 2009,
http://app.wshc.gov.sg/cms/Portals/0/WSHC%20Forum_case%20study_(industri
al
_site%20accidents
)&_Prevention_of_Heat%20Stroke.pdf
United States Department of Labour, Occupational Safety and Health Administration, 01 January 1995, Protecting Workers in Hot Environments, USA,
http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=FACT_
SHEETS&p_id=167 |
