They can seem like harmless substances - sugar, coal, wood dust, flour - however in certain conditions and across many industrial processes, dust from these - and other substances can become the fuel for an explosion. Many workers have died and hundreds have been injured over the past few decades as a result of dust explosions. Part of the problem is that dust explosion hazards are often unrecognized. Investigations of such accidents have shown that the material safety data sheets (MSDSs), which are regulated in Canada by the Workplace Hazardous Materials Information System (WHMIS), did not adequately describe dust hazards for the substances involved in these explosions.
The Occupational Safety & Health Administration (OSHA) in the United States does not currently have a specific standard on combustible dust hazards; however they have several standards that apply to combustible dust handling facilities, as well as the General Duty Clause. The Globally Harmonized System of Classification and Labelling of Chemicals (GHS) may eventually include a "combustible dust" hazard class. In Canada, although there is currently no combustible dust hazard class under WHMIS, suppliers are required to declare all hazards of the product on MSDSs, as a condition of sale and importation. The requirement is clearly documented in the Controlled Products Regulations (CPR):
12(11) A material safety data sheet shall disclose, in addition to the information required to be disclosed by subsection (2), any other hazard information with respect to the controlled product of which the supplier is aware or ought reasonably to be aware.
MSDSs must identify this hazard and disclose information on appropriate engineering controls to be used to prevent these explosions. Unfortunately the dust explosion hazard is not always declared, contributing to a general lack of awareness of this hazard amongst workers, and potentially putting them at risk for injury or even death.
Industries and substances at risk of dust explosions
A combustible dust explosion hazard may exist in a variety of industries, including:
- metal processing
- wood product manufacturing
- chemical manufacturing
- food and pharmaceutical production
- grain storage
- fabrication of rubber and plastic products
- coal-fired power plants
Combustible materials connected with dust explosions include dusts from coal, chemicals, wood, rubber, grain, sugar, flour, and metals. Most natural and synthetic organic materials, as well as some metals, can form combustible dust if they are processed in powdered form.
How dust can explode
For a dust explosion to occur, five conditions must be present at the same time. The five elements are referred to as the explosion pentagon, and include:
- combustible dust (fuel)
- ignition source (spark or heat)
- oxygen in air (oxidizer)
- dispersion of dust (into the air forming a dust cloud)
- confinement of the dust cloud (building or ceiling)
A dust cloud that is ignited within a confined or semi-confined vessel, area, or building, burns very rapidly and may explode. This could cause fires, additional explosions, flying debris, and the collapse of parts or all of the building.
An initial explosion that occurs in processing equipment or in an area where there is an additional accumulation of dust, may shake excess dust loose, or damage a containment system (such as a duct or vessel). The additional dust released into the air, if ignited, can cause one or more secondary explosions that can be even more destructive than the first explosion.
Although suppliers cannot predict every possible use of their products, they can help prevent explosions and injuries by ensuring that MSDSs contain the complete hazard information workers need to work safety with substances and materials that could potentially combust and/or explode.
Hazard-Specific Issues - Dust Explosibility, Health Canada
Hazard Communication Guidance for Combustible Dusts, Occupational Health and Safety Administration (OSHA)
Combustible Dust, OSHA
Investigation Report - Combustible Dust Hazard Study, United States Chemical Safety Board, PDF
WHMIS site, Government of Canada
More about WHMIS, CCOHS
CCOHS' CHEMINFO database identifies potential combustible dust hazards as well as any reports of dust explosions involving that chemical.
Alerts & Bulletins
We've seen those who work high above the ground, suspended on platforms as they construct buildings, wash windows or make repairs. Tragically, on Christmas Eve a suspended platform at an Ontario apartment building collapsed, falling 13 floors to the ground. Four construction workers died and another was severely injured.
In an effort to help protect workers who perform their duties from suspended work platforms, the Ontario Ministry of Labour (MOL) is conducting an enforcement campaign over the winter months, targeting fall hazards in the construction sector. Inspectors are checking for hazards involving suspended platforms at construction sites and looking for compliance with fall protection requirements, including appropriate fall-related equipment and adequate worker training.
The MOL issued a hazard alert providing information on the safe use, maintenance and inspection of suspended work platforms and control measures to minimise the risks of using this equipment. The equipment being used and the work being performed must be fully evaluated in order to comply with the Occupational Health and Safety Act (OHSA) and its regulations.
Types of suspended work platforms
Swing stages are the most commonly used suspended work platforms (suspended platforms or suspended scaffolds). They are used for window cleaning or conducting repairs to the exterior of buildings and consist of a work platform, guardrails and a suspension system.
Multi point suspended scaffolds are specialized suspended work platforms that have specific design and operational requirements.
The most significant hazard associated with swing stages is workers falling from height. Workers can also fall if the swing stage over-turns because the counterweight does not have the adequate weight or if point of support at the edge of the building fails. The swing stage can also collapse if it is overloaded, the platforms are not attached properly, or if the motors, platforms or wire ropes are damaged from exposure to chemicals or corrosive materials, or not properly maintained.
Employers and supervisors are required to take every precaution reasonable in the circumstances to ensure the health and safety of workers. The MOL outlined the following guidance to control the hazards.
Proper training: Workers working on a suspended platform or suspended scaffold who may use a fall protection system must receive comprehensive fall protection training. They must also be trained how to use and inspect the platform or scaffold.
Fall arrest system: A worker who is on - or is getting on or off - a suspended platform or suspended scaffold must wear a full body harness. The harness must be connected to a fall arrest system with an independent lifeline, or that is securely fastened to a suspended platform or scaffold that has more than one independent means of support.
Proper design, construction and use of equipment: Every suspended platform or suspended scaffold must be installed, maintained and used according to all safety regulations, standards and the manufacturer's specifications. The platform must not be overloaded. Equipment must be maintained in a condition that does not endanger a worker. Scaffolds with more than one platform or that exceed weights prescribed in safety regulations must be designed, erected and inspected according to applicable regulations.
Maintenance of equipment, materials and protective devices: Employers must ensure that the equipment, materials and protective devices are maintained in good condition.
Proper inspection of equipment: Suspended platforms or suspended scaffolds must be inspected by a competent
worker each day and before they are used, and at the start of each shift.
The above synopsis is an overview of the hazard alert from the MOL and is not intended to be a comprehensive record of health and safety regulations or precautions related to suspended work platforms.
More information about suspended platforms and scaffolds
Read the full alert from MOL
Dos and don'ts when working on a suspended platform, CCOHS
Occupational Health and Safety Act, Ontario
February 29th. It's the one day on the calendar that does not repeat, which is why it was chosen for International Repetitive Strain Injury (RSI) Awareness Day. In non-leap years, it is observed on February 28th. On this day, workers, health and safety professionals, health care practitioners and others take the opportunity to help raise awareness about RSIs and the need for action aimed at prevention, rehabilitation and compensation.
What are RSIs?
Repetitive strain injuries, also known as work-related musculoskeletal disorders (WMSDs), is an umbrella term to describe a family of painful disorders affecting tendons, muscles, nerves and joints in the neck, upper and lower back, chest, shoulders, arms and hands. WMSDs are a serious occupational health concern across the world and are recognized as leading causes of significant human suffering, loss of productivity, and economic burdens on society.
WMSDs can be caused by work activities that are frequent and repetitive, or activities with awkward postures, including:
- fixed or constrained body positions
- continual repetition of movements
- force concentrated on small parts of the body, such as the hand or wrist
- a pace of work that does not allow enough rest between movements
Heat, cold and vibration may also contribute to the development of WMSDs. These disorders are generally caused by a combination of these factors - rather than one individual factor.
The best way to eliminate a hazard is to eliminate the source. With WMSDs, the main source of the hazard is the repetitiveness of work. Prevention efforts should focus on avoiding the repetitiveness patterns of work through proper job design. Where this is not possible, preventive strategies involving workplace layout, tool and equipment design, and work practices should be considered. It is important to recognize these disorders early because medical treatments become less effective the longer these injuries go on.
Preventive and control measures, in order to be truly effective, require involvement of workers, their representatives, and management.
Symptons, causes and prevention tips for musculoskeletal disorders, OSH Answers (CCOHS)
Look for and listen to the CCOHS free podcast with tips to prevent RSIs, available mid February 2010.
When you work all day sitting at a desk or in front a computer, it can be easy to forget to change position or stretch your aching muscles. The colourful poster from CCOHS, It's a Stretch provides a friendly reminder. The poster is printed with English on one side and French on the other. It is available in full colour print for a cost, or as a free download.
CCOHS podcast producer Jennifer has been busy adding to the popular, ever growing podcast program with several new episodes. Listen and learn. They're free.
We live in a world of constant communication and while that comes with many positive aspects, there can be downsides. Listen to what cyberbullying is and ways to prevent you from becoming a target.
Listen to it now! 3:37 minutes
Systematic Approach to Creating Healthier and Safer Workplaces
Listen and learn about the easiest way to manage health and safety and how management systems can help you achieve better performance and a healthier workplace.
Listen to it now! 8:29 minutes
Winter Driving Tips
Listen to tips on how to drive safely in the cold Canadian winter and in the extreme weather conditions such as snow, ice and slush that go along with it.
Listen to it now! 3:25 minutes
Noise is one of the most common health hazards in the workplace and can affect people differently. Learn about the types of workplace noise and how it can affect your health.
Listen to it now! 4:22 minutes
Watch for Preventing Repetitive Strain Injuries - Coming in mid February
See the full list of podcasts.
There are still spaces available for CCOHS' Forum III, taking place March 8 and 9 in the National Capital Region.
Don't miss your opportunity to hear experts speak on the following topics:
- Leading @ the Speed of Change
- Leadership Within the System
- Employer and Labour Perspectives on Leadership and Responsibility
- Implementing Successful Participatory Ergonomic Programs: Opportunities and Challenges
- Towards a National Prevention Strategy for Workplace Violence in Canada
- Four Generations - Four Approaches to Work: Enhancing Training & Coaching for All
When you attend Forum III, you can earn professional education maintenance points from the Board of Canadian Registered Safety Professionals, Canadian Registration Board of Occupational Hygienists (CRBOH), American Board of Industrial Hygiene (ABIH), and the Ontario Kinesiology Association (OKA). While this event is not officially endorsed by the Canadian Nurses Association (CNA), nurses may claim it as a continuous learning (CL) activity toward renewal of the CNA certification credential.
Learn more about the Forum III program and register.
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The Health and Safety Report, a free monthly newsletter produced by the Canadian Centre for Occupational Health and Safety (CCOHS), provides information, advice, and resources that help support a safe and healthy work environment and the total well being of workers.
© 2017, Canadian Centre for Occupational Health and Safety
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