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BCCSA explores how best to safely handle hazardous isocyanates

Peter Caulfield
BCCSA explores how best to safely handle hazardous isocyanates

A recent webinar by the BC Construction Safety Alliance (BCCSA) was on a subject that will be new to many people in construction.

Isocyanates – The Silent Sensitizers dealt with the same-named hazardous chemicals that are often found in Canada in parkade membranes and polyurethane spray foams.

The session combined the technical and scientific how-to of working safely with isocyanates with the real-life experience of managing the chemicals on-site.

The presenters of the hour-long session, which was moderated by BCCSA’s Tanya Steele, were Melanie Gorman-Ng, BCCSA health and exposure scientist (and adjunct professor, UBC School of Population and Public Health) and Jeremy Laird, safety supervisor with Ledcor Construction Ltd.

Gorman-Ng and Laird discussed the health effects of isocyanates, the WorkSafeBC requirements regarding the chemicals, and how to ensure workers are protected from exposure to them.

Using a case study of isocyanates control in a B.C. parkade, they identified some common mistakes in dealing with isocyanates and how to fix them.

“Isocyanates are very reactive with other chemical compounds, which is part of the reason why they’re useful,” said Gorman-Ng. “However, that same reactivity can also have negative health effects, the most serious of which is occupational asthma.”

Isocyanates are classified by WorkSafeBC as sensitizers, which means workers can develop a sensitivity to them, even at low levels of exposure.

Workers who are sensitized need to be reassigned, since they can no longer tolerate any exposure to the sensitizer in question.

Sensitizers have special requirements for exposure control under the Health and Safety Regulation, and WorkSafeBC’s occupational disease prevention strategy has made them a priority.

“BCCSA has been getting an increasing number of requests for information about isocyanates,” said Gorman-Ng. “It’s clear the construction industry wants help with them.”

WorkSafeBC has an isocyanates section on its website with some best practices and resources:

And this video illustrates the hazards of isocyanates while applying finish coatings:

Laird says the presentation was derived from a review of an isocyanates exposure control plan that had been submitted to Ledcor by a contractor.  

The contractor had been asked to demonstrate the effectiveness of its control measures before applying a parkade membrane.

“While conducting the verification check using smoke to show air movement and ventilation, the smoke moved deeper into the parkade, which would indicate that air movement is less likely to be effective at protecting workers,” said Laird.

Ledcor partnered with VanDriel OHS Consulting (VOHS), a Vancouver industrial hygiene consulting company, to help evaluate risk and to develop mitigation controls. 

Ledcor, VOHS, the application contractor, WorkSafe BC, and the membrane supplier researched the product data sheets and built a negative-pressure containment unit.

VOHS conducted air movement and ventilation tests to see if the new and revised exposure controls reduced worker exposure to isocyanates.

“The team recognized there could be misinformation in the industry on the safe use of isocyanates products,” said Laird. “Ledcor believed lessons and best practices should be shared with the industry, so we partnered with BCCSA to develop the Isocyanates – the Silent Sensitizers webinar.”

The session on isocyanates is part of a series of webinars that is replacing BCCSA’s Construction OHS (Occupation Health and Safety) annual conference.

“We decided to cancel 2020 OHS conference because of the Covid-19 pandemic,” said BCCSA executive director Mike McKenna. “We polled our industry contacts, and they told us their number-one concern was isocyanates.”

Since the isocyanates webinar took place, there has been a two-part session on multi-employer workplace roles and responsibilities.

Part 1 focused on the roles and responsibilities of owners, prime contractors and employers for worker health and safety on construction sites. “Understanding each other’s health and safety responsibilities, plus good communication, helps to organize the coordination of work in a way that keeps all workers safe and healthy,” said presenter Andrew Kidd, manager of WorkSafeBC prevention field services in construction zone one,

Topics for the session included planning and coordinating multi-employer workplaces, identifying the prime contractor and owner, and distinguishing the legal responsibilities of prime, owner, qualified coordinator, supervisor and worker.

Part 2 looked more closely at the principles of enforcement and due diligence and how they relate to the roles and responsibilities of the owners, prime contractors and employers on construction sites.

“In construction there are many moving parts, many employers and many workers for each employer,” said Kidd. “If the work of one employer can have an effect on the health and safety of another employers’ workers, it is critical that there is oversight in place to ensure the health and safety of all workers at that workplace.”

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