Module 1: Occupational Hygiene - Section 5: Instrumentation

OH5.10: Evaluation of Heat Stress - Thermal Regulations

Thermal regulations

Regulation 5(4) of the Environmental Regulations for Workplaces regulates workers' exposure to hot environments. The regulations require, where the average WBGT index exceeds 30 ºC in the environment in which an employee works, that an employer take the following steps:

• Bring down the index to below 30 ºC;
• If that is not reasonably practicable, to:
• Certify the workers fit for work in hot environments.
• Acclimatise workers to working conditions.
• Encourage every employee to partake of at least 600 ml of fluid per hour.
• Train every employee in precautions to be taken to avoid heat stroke.
• Provide prompt first aid treatment in the case of heat stroke.

Heat exposure limits

Heat stress is a function of environmental conditions and heat generated by the body. To predict how the body will react one needs to take into account the nature of the work performed as well as environmental heat. The American Conference of Governmental Industrial Hygienists has compiled a list of permissible heat exposure threshold limit values, (TLV's) and these are reproduced below. These TLVs are for workers who are acclimatised to hot work environments, to the work they do, and who are physically fit.

REFERENCES:

1. Schoeman JJ. Temperature Extremes. In: Occupational Hygiene. Edited by Schoeman JJ and Schroeder HHE. Published by Juta & Co., 1996.
2. Parsons KC. Assessment of Heat Stress Indices. In: Encyclopaedia for Occupational Health and Safety. http://www.ilo.org/safework_bookshelf/english/.
3. Ogawa T. Heat Disorders. In: Encyclopaedia for Occupational Health and Safety, Fourth Edition. Published by the International Labour Office, 1998.
4. Working in Hot Environments - Health Effects Canadian Centre for Occupational Health and Safety. .
5. Working in Hot Environments - Control Measures Canadian Centre for Occupational Health and Safety. .
6. American Conference of Governmental Industrial Hygienists. Documentation of Threshold Limit Values and Biological Exposure Indices. Latest Edition.

General Introduction to Occupational Health: Occupational Hygiene, Epidemiology & Biostatistics by Prof Jonny Myers is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License