MRO Magazine

Manufacturers urged to adopt new heat stress plan for workers

Toronto, ON -- Aug. 16, 2002 -- To assist workplaces in evaluating heat stress conditions, the Occupational Health...

Health & Safety

August 16, 2002
By MRO Magazine

Toronto, ON — Aug. 16, 2002 — To assist workplaces in evaluating heat stress conditions, the Occupational Health Clinics for Ontario Workers-Hamilton (OHCOW) have developed a new Humidex-based Heat Stress Response Plan.

The tool provides a Notification Plan with seven ranges that will help employers and workers identify ways to prevent heat-related illnesses through education, monitoring the workplace and intervention.

The plan uses the current American Conference of Governmental Hygienists Heat Stress and Strain TLV (threshold limit values) used by the Ontario Ministry of Labour.

“Increased body temperatures can result in death if the workplace is not properly monitored and workers aren’t educated to recognize the symptoms of heat illness,” said Mary Cook managing director of OHCOW. “This new tool is simple to use, the other system, the Wet Bulb Globe Temperature (WBGT), is too complex for many workplaces and focuses on the individual rather than on the work environment.”


Recently, Ontario reached record-breaking temperatures in a severe summer heat wave. Humidity, heat and smog, reached dangerous levels, causing emergency heat warnings throughout the province, with daytime temperatures reach at least 30 degrees Celsius.

“A heat wave can mean the temperature in workplaces can become dangerously high,” said Cook. “Workers on assembly lines or in manufacturing plants are exposed to not only heat but also to humidity posing severe hazards to their health and safety.”

“There have been two heat stroke fatalities in the past 10 years, a bakery worker in Barrie and a student, on his second day, collecting garbage,” said Cook. “These deaths are tragic and could have been prevented. It’s impossible to calculate how many other illnesses or deaths could have been prevented through education and a simplified plan to deal with workplace hazards.”

OHCOW-Hamilton designed the Humidex Heat Stress Response Plan as a precautionary tool to assist workplaces in identifying heat illness before it becomes a medical emergency. Other factors must be considered, including medical conditions, medications being taken, workload, excessive clothing, age, weight, etc.

In all workplaces where there are other sources of heat in addition to the weather, a monitoring system must be in place to protect workers’ health, said Cook. In workplaces with excessive radiant heat, such as iron and steel foundries, a more complex system needs to be in place.

Currently, the Canadian Auto Workers (CAW) and General Motors Canada are working jointly to implement this new tool, the Humidex-based Heat Stress Response Plan, into GM workplaces.