As an employer, it is crucial to assess the risk of heat stress to employees and ensure their safety. There are two main factors that contribute to the risk of heat-related illness:
- Environmental heat: This is generated by warm or hot surroundings.
- Physical activity – metabolic heat: This heat is produced by the body and corresponds to the workload.
This blog offers guidance on managing these specific risks so employers can make well-informed choices. OSHA (Occupational Safety and Health Administration) also provides standards and additional guidelines that can assist employers in making the correct decisions.
Environmental Heat Factors
When assessing environmental heat to determine if it is too hot for workers, employers should use reliable methods for accurate measurement and evaluation. The Wet Bulb Globe Temperature (WBGT) index is a widely recommended approach for this purpose. It considers factors like temperature, humidity, wind speed, and radiant heat to provide a comprehensive measure of heat stress.
To evaluate environmental heat using the WBGT index, employers should:
- Use a reliable WBGT device: Obtain a specialized WBGT device that includes temperature sensors, a wet bulb sensor, and a globe thermometer for accurate heat stress measurement.Monitor measurements: Allow the WBGT device to record the necessary measurements for an appropriate duration, capturing representative work conditions.
- Proper device placement: Position the WBGT device at the work location where workers are exposed to heat stress, ensuring it is unaffected by artificial heat or cooling sources.
- Consider additional factors: Account for other influences on heat stress, such as radiant heat, direct sunlight, or air movement, alongside the WBGT measurements to obtain a more precise assessment.
- Monitor measurements: Allow the WBGT device to record the necessary measurements for an appropriate duration, capturing representative work conditions.
- Interpret results: Compare the measured WBGT values with established heat stress guidelines or standards provided by relevant authorities. These guidelines specify thresholds or action levels that require specific precautions or control measures. Follow OSHA’s recommendations and standards for heat exposure.
Physical Activity Considerations
When workers participate in strenuous labor, their bodies generate internal heat, known as “metabolic” heat. To prevent the risky combination of environmental and metabolic heat, employers need to be mindful of the level of physical activity their workers undertake. Workloads can be categorized as light, moderate, heavy, or very heavy, based on the nature of the tasks involved.
Here’s a breakdown of each workload classification:
- Light: Involves minimal arm and leg movement while sitting or standing.
- Moderate: Consists of continuous, modest-intensity activities like light pushing/pulling or normal walking.
- Heavy: Encompasses intense upper body exertion, such as carrying heavy loads or sawing.
- Very heavy: Requires vigorous activity performed at an almost maximum pace.
It is essential to recognize that heavy and very heavy work poses the highest risk of heat-related illnesses. Extra precautions should be taken for workers engaged in intense labor activities that significantly elevate their heart and respiration rates due to exertion. These precautions include providing frequent rest breaks and scheduling work during cooler parts of the day.
When unsure about a worker’s exact level of physical activity, it is recommended to assume a higher workload or seek guidance from a qualified occupational safety and health professional to ensure adequate measures are implemented to mitigate heat-related risks. OSHA provides a table that shows more examples of activities in each workload category.
Determine How Hot is Too Hot – Avoid Heat Stress
To assess heat stress risks, employers consider multiple factors related to the job, environment, and worker. Here is a list of the process:
- estimating the workload (light, moderate, heavy, or very heavy)
- measuring environmental heat using methods like the WBGT index
- making clothing adjustments
- evaluating worker acclimatization to heat
- utilize tables/guidelines that provide information on the combination of workload, environmental heat (effective WBGT), and acclimatization status to determine if the total heat stress level (here is one table as an example)
The best thing you can do is seek guidance from a qualified occupational safety and health professional. These professionals have the expertise and knowledge to assess heat conditions, evaluate potential risks, and provide recommendations on appropriate measures to ensure worker safety in hot environments.