Heat-stress occupational hygiene programme

This programme targets employees working in conditions where:

• The wet bulb temperature is equal to or greater than 27,5 degrees Celsius, or
• The dry bulb temperature is equal to or exceeds 37,0 degrees Celsius.

Occupational health practitioners must familiarise themselves with and apply the Codes of Practice (COP) drawn up in accordance with the guideline for the mandatory COP on heat stress management of the Department of Minerals and Energy. Employees who need to work in such environments must meet all the physical requirements and pass the necessary screening tests prescribed in this guideline and COP referred to above before being declared fit to work.

An effective programme of thermal stress management is one that links the occupational hygiene programme to medical surveillance.

Heat stress risk assessment

Risk assessment should be able to:

• Define the process;
• Describe the activity areas with regard to:
• significant sources of heat stress;
• the health effects;
• nature of the key work operations; and
• the number of employees who are exposed to heat stress and their occupations.
• Describe the pattern, duration and frequency of employee exposure to heat stress;
• Compare the actual exposure levels with occupational exposure limits;
• Put in place measures that control elimination, substitution, engineering, administration and personal protective clothing; and
• Monitor of the effectiveness of the occupational hygiene programme.

Categorisation of the thermal environment

Categorisation of the thermal environment should be performed for the purposes of monitoring and should be clearly demarcated on a plan/sketch. When there is the need a thermal environment can be reclassified and thermal environments must be reassessed whenever:

• exposure levels change;
• there are employee complaints;
• processes are changed;
• illness occurs; or
• new regulatory requirements demand this.

Heat stress management

• The occupational hygiene programme aims to address issues of risk assessment, categorisation of the thermal environments, heat stress measurement, monitoring and recording;
• There must be a working organisational structure for a heat stress management programme;
• A system has to be in place for medical examination;
• A method has to be developed for heat tolerance screening;
• Knowledge of work practices is essential;
• There must be effective monitoring of absenteeism;
• Water and nutritional requirements; and
• Short-term exposures to extremely hot environments during emergency work.

Measurement

Measurement methodology should include the following:

• Record of each parameter of the environmental thermal load;
• Instrument used;
• Specification/accuracy;
• Calibration/certification; and
• Methodology and data recording format.

Heat stress monitoring

Monitoring of heat stress should be undertaken on an annual basis. Accurate and meaningful results, which are representative of all full working shifts for that thermal environment, should be obtained from this monitoring.

Record keeping

Record keeping and reporting should follow the provisions of the Mine Health and Safety Act. The information in the records should include reasons for any change of category in the thermal environment, for example controls not operating effectively, and hierarchy of controls initiated, i.e. elimination, engineering controls, administrative controls and personal protective equipment.