Ensuring Safe Work Conditions: Wet Bulb Globe Temperature and Heat Stress Monitors

Consider this fact: The Canadian Centre for Occupational Health and Safety advises that no legislation has set a maximum temperature above which work should stop! How, then, is an employer or sports team manager able to ensure an environment is within safe working conditions?

Without any monitoring or safety procedures for identifying heat stress conditions, workers can develop:

  • Heat stroke
  • Heat exhaustion
  • Heat cramps
  • Heat collapse (“fainting”)
  • Heat rashes
  • Heat fatigue

US Marines training in South Carolina discovered this problem in the late 1950s. The high humidity and temperature, combined with the requirement to exercise in full uniform, resulted in a high number of heat stroke casualties. The Navy investigated the effects heat had on exercise performance. As a result of these studies, a heat index named the Wet Bulb Globe Temperature (WBGT) was established.

Why is a heat index like this necessary? Traditional mercury and digital thermometers are capable of indicating air temperatures, however, air temperature is not the only factor that puts stress on the human body. Humidity, solar radiation and airflow (wind) are other variables that must be taken into consideration. The WBGT combines all of these variables and provides a single readout to qualify the present working condition.

Heat Stress MeterToday, a handheld electronic device called a Heat Stress Meter is used to calculate the WBGT. As mentioned previously, the Heat Stress Meter measures many variables such as humidity, solar radiation and airflow. Some meters also measure wet bulb, air temperature and dew point. The Heat Stress Meter delivers a quick and accurate result in order to determine real time working conditions employees face on the job. Testing with a Heat Stress Meter is useful when workers are:

  • Outdoors in hot and humid environments
  • Indoors in a foundry, mill or similar environments
  • When workers must wear semi-permeable or impermeable clothing, which contributes to heat stress. Data logging Heat Stress Meters allow the user to record a number of different readings over a period of time. Analysts can therefore track and compare results at one or many locations. Furthermore, historical data can also be archived and looked back on at future dates.

Perform a walk-around and identify hot and humid conditions where it may be possible to utilize a Heat Stress Meter. When possible, implement discomfort-reducing solutions like these:

  • Recommend light, loose-fitting clothing be worn
  • Allow and require more frequent rest breaks
  • Install fans or air conditioning equipment
  • Develop a flexible work schedule that allows less physically impactful operations to be carried out during peak temperature times • Create shaded areas with screens or umbrellas
  • Distribute non-alcoholic and non-caffeinated cold drinks.

In addition, develop an acclimatization program. Studies have proven that many people who are accustomed to high temperature and humidity environments can perform within these conditions much better than those who are not. For example, introduce the new person to the environment allotting only a 20% time requirement of normal exposure. Slowly build up their exposure time to 100% and this will give their body time to adjust.

Educate your employees on the dangers of heat stress, watch for the symptoms and implement as many of the reduction strategies as possible. Implement measuring Wet Bulb Globe Temperatures with a Heat Stress Meter into your procedure to ensure safe working conditions. Making use of all of these methods will result in a much safer workplace for your team!

This article was originally published by

Instrument Calibration Services

We calibrate test and measuring equipment for companies across Canada to ISO 17025 standard, traceable and provide accredited calibration service for almost all test and measurement instruments. As an ISO 17025 accredited Company located in Brampton (Greatest Toronto Area) we offer highest quality In-Lab or On-Site Accredited Calibration Services.

Calibration lab for Measurement Instruments

In our Type II Laboratory accredited to ISO:17025 by A2LA we provide clients with calibration of various instruments using manufacturer's specification and ISO standards as reference. Located in Brampton, Mississauga Toronto area, our metrology lab offers calibration services for measuring instruments. 

Service and Repair information

We are ready to repair your measurement tool providing a great turn around time. We service quickly and efficiently at affordable prices almost any measurement instrument brand or model. We repair Torque Testers, Force Gauges, Micrometers, Test Stands, Calipers, Optical Projectors, Torque Wrenches, Digital Readout Systems, Height Gauges, Multimeters, Dial Indicators, Pressure Gauges and more...