Low humidity levels in winter make dust easy to disperse and ignite
With the number of new and reopening sawmills in Ontario, this is an important reminder that the risk of a dust explosion increases when low humidity levels – like those seen in winter months – make dust easy to disperse and ignite.
In fact, industrial incident investigations by the U.S. Chemical Safety Board found that seven out of eight fatal combustible dust explosions from 1995 to 2009 occurred during cold winter months when these weather conditions were most prominent, according to a hazard alert issued by WorkSafe BC.
One of the two tragic sawmill incidents in British Columbia occurred in the middle of winter, the second occurred in early spring. View the CBC The National video clip on the BC sawmill explosions.
A number of changes can commonly occur in wood processing facilities as the weather becomes colder.
- Control measures and clean-up practices that rely on the use of water may not be suitable or effective
- Openings such as bay doors and wall dampers may be closed up increasing the degree of enclosure and reducing natural ventilation or make up air
- Ventilation may be reduced or shut down to conserve heat
- Re-circulation of air from exhaust systems may also increase
- Portable heating units potentially introduce additional ignition sources into workspaces
Going into the winter months it is important to maintain attention on controlling risks associated with combustible dusts.
Tom Welton, Director Industrial for Workplace Safety North, encourages mills to contact WSN Consultant-Trainers for guidance and support in recognizing, assessing and controlling the risks associated with the impact of the environment on dust accumulations and the methods used to control dust in the winter.
“A significant amount of resource material is now available from Worksafe BC with regards to the investigation, as well as supporting resources associated with combustible dust in a mill application, " says Welton. "WSN Consultant-Trainers have been kept up to date on this resource material, and can be a great support to assist mills in addressing this increased concern with the onset of the winter months.”
Hazard Alert: Combustible dust – increased risk in winter – Please post in your workplace and encourage discussion