Toxic air, flammable vapours and the only way out is through a small opening – this situation is just one of many scenarios that describe what it’s like to work in a confined space. While hazards can be found in every type of workspace, confined spaces have the potential to be even more hazardous. Learn more about some of the hazards with working in confined spaces and what you can do to control the risks.
What is a confined space?
Generally speaking, a confined space is an enclosed or partially enclosed space that is not primarily designed or intended for human occupancy, has a restricted entrance or exit, and can represent a risk to the health and safety of anyone who enters, due to one or more of the following factors:
- its design, construction, location or atmosphere
- the materials or substances in it
- work activities being carried out in it, or the
- mechanical, process and safety hazards present.
Confined spaces can be found in almost any workplace. Examples include: silos, vats, hoppers, utility vaults, water cisterns, clean water wells, tanks, ship holds, sewers, pipes, access shafts, truck or rail tank cars, aircraft wings, boilers, conveyors, cellars, tunnels, manholes, manure pits, storage bins and other such spaces that workers could enter to perform work. Ditches or trenches may also be a confined space when access or a way out is limited.
All hazards found in a regular workspace can also be found in a confined space. The main hazards associated with confined spaces include: oxygen deficiency or enrichment, fire or explosion, toxicity, and drowning.
Too little oxygen can cause brain damage, the loss of consciousness, and potential suffocation. Too much oxygen can increase the risk of fire or explosion. Natural ventilation alone will often not be sufficient to maintain breathable quality air.
A high percentage of deaths in confined spaces result from oxygen deficiency and lack of quality air testing. Of the workers killed each year while working in confined spaces, many of them have been would-be rescuers who often suffer the same fate as those they are attempting to save.
Fire and explosions
Inadequate ventilation can result in an accumulation of gases or dusts that can combust when exposed to electricity, a welding spark, or open flame.
Gases from work activities such as painting and welding, and sources such as liquid manure or compost can produce gases including hydrogen sulfide, methane, carbon monoxide, and solvent vapours that can cause dizziness, loss of consciousness, permanent damage to health, and death.
In the event of a flood or engulfment by a free-flowing solid (for example grain in a silo), the entrance or exit of the confined space may be obstructed, preventing the worker from getting out in time. Drowning can also occur by falling into holding tanks, ponds and pits filled with liquid.
More hazardous than other work spaces
All of these hazards may not be obvious so a person qualified with the proper training and experience must conduct a confined space hazard assessment before any workers enter the space, considering these factors:
- Self-rescue by the worker is more difficult.
- Rescue of the victim is more difficult. The interior configuration of the confined space often does not allow easy movement of people or equipment within it.
- Conditions can change very quickly and without warning.
- The space outside can impact the conditions inside the confined space and vice versa.
- Work activities may introduce hazards not present initially.
Many factors need to be evaluated when looking for hazards in a confined space. An error in identifying or evaluating potential hazards can put the worker's life in danger.
Preparation and prevention
To effectively control the risks associated with working in a confined space, a Confined Space Hazard Assessment and Control Program should be implemented. Before putting together this program, make sure to review the specific regulations that apply to your workplace. All jurisdictions in Canada have varying regulations dealing with confined space entry.
Workers should not enter the confined space until it is made safe to do so by taking precautions.
For each job, determine if it is absolutely necessary that the work be done inside the confined space. In some cases it may be possible to do the work outside the confined space.
Air quality testing needs to be performed by a qualified person trained in using detection equipment. Always make sure that the testing equipment is properly calibrated and maintained. Air sampling should show that there are safe limits of oxygen content in the confined space, hazardous gases are not present, and that ventilation is working properly. This testing should be ongoing while work is being done.
Remove or restrict any liquids or free-flowing solids in the confined space to eliminate the risk of drowning or suffocation. All pipes should be physically disconnected or isolation blanks bolted in place; closing valves is not sufficient.
Entry and exit openings for the confined space must be large enough to allow the passage of a person using personal protective equipment (PPE).
What employers can do
- Have a confined space program that includes written procedures
- Identify confined spaces
- Post warning signs and secure entry to confined spaces
- Determine the hazards for each space
- Develop confined space entry plans for each space
- Train workers in safe work procedures specific to the work being done in the confined space
- Use an entry permit system
What workers can do
- Recognize confined spaces
- Know the hazards
- Follow safe work procedures when in a confined space
- Stay aware of changing conditions while performing the work
- Know when to stay out of confined spaces
- Don’t attempt to rescue others without proper training and equipment
- Confined Space fact sheet, CCOHS
- Confined Spaces Guideline, Ontario Ministry of Labour
- Occupational Health and Safety Code 2009 Part 5, Alberta Ministry of Jobs, Skills, Training and Labour, PDF
- Confined Spaces - No Easy Way Out Occupational Health and Safety, Labour Program Canada
- Confined Spaces, WorkSafe BC
- Confined Spaces: Recognizing the Danger, WorkSafeNB, PDF
The use of fibre cement siding in construction and renovation is on the rise with many new building projects using this durable building material as an alternative to wood siding. But these products can contain as much as 50% crystalline silica and cutting this material with a power saw has been shown to cause excessive exposure to respirable crystalline silica. Breathing this dust can lead to silicosis, a deadly lung disease. Exposure to crystalline silica has also been linked to lung cancer, kidney disease, reduced lung function, and other disorders. No effective treatment exists for silicosis, but it can be prevented by controlling workers exposures to dust containing crystalline silica. A National Institute for Occupational Safety and Health (NIOSH) study offered guidance on how exposures could be reduced.
Fibre cement siding is most commonly and effectively cut with power saws such as circular saws and compound miter saws. These saws are normally used with blades specifically designed to cut fibre cement siding and minimize dust generation. Several commercially available circular saws have dust-collecting features such as hoods and exhaust take-offs that can be connected to vacuum cleaners or dust-collection bags.
NIOSH scientists conducted a study to develop practical engineering control recommendations for respirable crystalline silica from cutting fibre cement siding. Results from the study suggested that connecting a dust-collecting circular saw to a regular shop vacuum can be an effective, simple and low-cost (compared to HEPA vacuums) engineering solution to control the generated dust.
Local exhaust ventilation (LEV) system
- Use a shop vacuum with an air-flow rate of 30 CFM or higher. A vacuum hose can be used to attach the circular saw to the shop vacuum. The hose should be of sufficient size (3cm or 1.25 inch or greater in diameter).
- A high efficiency disposable filter bag can be used as a pre-filter in the shop vacuum to capture most of the dust. Use in conjunction with a cartridge filter.
- The shop vacuum and the circular saw can be plugged into an intelligent vacuum switch. This eliminates the distraction for the operator of turning on and off a dust collection system and ensures the vacuum is running while operating the saw, avoiding uncontrolled dust release. The switch also allows for delay in turning off the shop vacuum when the saw is turned off, removing the remaining dust in the vacuum hose following the cutting of a board. Some shop vacuums have incorporated such an intelligent vacuum switch. For those shop vacuums that don't have it, an aftermarket device with the same feature can be purchased and used.
Circular saws and blades
- Use only circular saws with a built-in dust collection container or shroud that functions as a hood, partially encloses the saw blade, and can be easily connected to the LEV system.
- Use blades designed to cut fibre cement siding. They provide a cleaner cut, offer a longer wear life, and may reduce the dust generated.
- When using a power saw, cut fibre cement siding outdoors when practical.
- Avoid cleaning up loose fibre cement dust on job site using dry sweeping, and use a vacuum instead.
- Provide a covered trash can near the work station for saw operators to dispose of collected dust. Dispose of fibre cement dust according to local regulations.
- Maintain the shop vacuum according to manufacturer recommendations.
- Inspect the shop vacuum daily for defects (new filter bags and cartridges inspected for holes, cuts, etc.) and that the filter bag and cartridge filter are changed regularly to prevent restricted air flow.
- These dust controls may greatly reduce worker exposure to hazardous dust; however, NIOSH recommends the use of half-facepiece particulate respirators with N95 or better filters for airborne exposures to crystalline silica at concentrations less than or equal to 0.5 mg/ m3 [NIOSH 2008].
Read the full alert (PDF) from NIOSH.
More resources from CCOHS
What are the Effects of Dust on the Lungs? fact sheet
Respirator Selection fact sheet
Silica, quartz fact sheet
Tips & Tools
Working indoors or outside, heat-related illnesses can strike with little warning. Heat exhaustion can result from working or playing in high temperatures. In working environments, such as firefighting, bakeries, steel mills, farms, factories, kitchens, and laundries, the hot conditions can suddenly overwhelm the body's ability to deal with heat, leading to potentially serious heat-related illness.
Heat exhaustion is caused by loss of body water and salt through excessive sweating. It is a severe form of heat illness. The signs and symptoms of heat exhaustion may start suddenly, and include:
- muscle cramps or weakness
- feeling faint
- heavy sweating
- high body temperature
First aid for heat exhaustion
- Move to a cooler, shaded location.
- Get medical aid.
- Stay with the person until help arrives.
- Remove as many clothes as possible (including socks and shoes).
- Apply cool, wet cloths or ice to head, face or neck.
- Spray with cool water.
- Encourage the person to drink water, clear juice, or a sports drink.
Tips to prevent exhaustion:
- Train workers and supervisors about the hazards leading to heat illness and prevention methods.
- Train workers to recognize symptoms in themselves and others. Encourage immediate reporting.
- Thirsty or not, drink water frequently – a cup every 15 to 20 minutes. Avoid caffeine and alcohol which can dehydrate you.
- It takes time to adjust to working in heat. Increase workloads and heat exposure gradually.
- Schedule frequent rest periods, with water breaks, in shaded or air-conditioned buildings, areas or vehicles. Dont over exert yourself.
Heat exhaustion can quickly become heat stroke, a medical emergency. Protect yourself from heat related illness by keeping yourself hydrated and your body cool.
For additional information on heat-related illness consult these resources:
Hot Environments - Health Effects and First Aid fact sheet, CCOHS
Download the Heat-Related Illness: Watch for Signs poster from CCOHS
Download the Keep Your Cool poster from CCOHS
Protecting Workers from Heat Illness Infosheet, OSHA-NIOSH, PDF
Fishermen, industry and government have released a plan aimed at making Nova Scotia's commercial fishing industry safer. Developed by the Safe at Sea Alliance – a group of fishermen, family members, industry, safety organizations, community leaders, and government – the Fishing Safety Now plan includes recommendations for the development of a safety toolkit, more education and awareness of safety requirements, and more training and safety drills.
"We need to do something to make the industry safer," said Dale Richardson, a swordfish and lobster fisherman from Sable River, Shelburne Co., and a Safe at Sea Alliance industry representative. "We won't fix everything overnight, but by having everyone in the same room – industry, Workers' Compensation Board, government, Nova Scotia Community College and the Transportation Safety Board, we're making giant leaps forward."
The Fisheries Safety Association of Nova Scotia and the Nova Scotia Fisheries Sector Council will take the lead on carrying out the 33 recommendations aimed at improving safety and ultimately, saving lives. Since 2007, 35 people have died working in Nova Scotia's commercial fisheries.
Highlights from the plan include better awareness of practices and regulations, more safety training and education and reviews of policies and processes for such things as weather forecasting and fisheries management.
"We're all committed to this work. We've built a solid foundation that will ensure these recommendations are carried out. The plan is only the beginning," said Stuart MacLean, CEO, Workers' Compensation Board of Nova Scotia.
Fishing safety is a key part of the province's Workplace Safety Strategy and the Commercial Fishing Strategy.
For a copy of Fishing Safety Now, visit http://www.safeatseans.ca.
Health and Safety To Go
This months Health and Safety To Go! podcasts feature the episodes Summer Safety Tips and Worker Fatigue.
Feature Podcast: Summer Safety Tips
Warm and sunny summer months mean more time being spent outdoors. And whether you work or play in the great outdoors, you are at greater risk of illness and injury resulting from excessive sun exposure and extreme heat. In this podcast CCOHS provides steps you can take to make your summer safe and injury free.
The podcast runs 4:59 minutes. Listen to the podcast now.
Podcast 2: Worker Fatigue
CCOHS explains how fatigue affects worker safety and offers tips on minimizing the effects of fatigue.
The podcast runs 4:24 minutes. Listen to the podcast now.
CCOHS produces free monthly podcasts on a wide variety of topics designed to keep you current with information, tips, and insights into the health, safety, and well-being of working Canadians. You can download the audio segment to your computer or MP3 player and listen to it at your own convenience... or on the go!
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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
Length: 6:00 minutes
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Locations Across Canada
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June 1-3, 2017