Ontario's Workplace Safety North has issued an alert that the risk of a dust explosion increases in winter months — when low humidity levels make dust easy to disperse and ignite.
Industrial incident investigations by the United States Chemical Safety Board found that seven in 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 WorkSafeBC.
One of the two tragic sawmill incidents in British Columbia occurred in the middle of winter, the second occurred in early spring.
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 work spaces.
Going into the winter months it is important to maintain attention on controlling risks associated with combustible dusts.
Mills are encouraged to contact Workplace Safety North for more information 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.