Understanding the Potential Risks and Hazards Associated Within Permit Required Confined Spaces
Many workplaces contain confined spaces that can present real or potential dangers to employees who must enter the space for work purposes. The information presented below will assist employers and employees in understanding the requirements for practices and procedures to protect employees in general industry, from the hazards of entry into permit required confined spaces.
OSHA standard 1910.146 permit required confined spaces, defines a confined space as –
- An area large enough and so configured that an employee can bodily enter and perform assigned work
- Has limited or restricted means for entry or exit
- Is not designed for continuous employee occupancy
A confined space is not limited to small areas such as manholes and ditches, but includes larger areas such as tanks, vessels and silos.
Working within a confined space requires a permit if the area has the potential as being a serious safety or health hazard. It is the employers responsibility to evaluate work spaces, to determine if it is a permit required confined space (PRCS)
If a confined space is designated as PRCS, then it is up to the employer to inform its employees, by posting danger signs or by other equally effective means of notification. The employer must also take the steps in preventing its employees from entering the space until a written space program is produced. The permit program must be available at the time of entry to all authorised entrants, or their authorised representatives – by posting it at the entry portal, or by any other effective means. The entrants can therefore confirm that pre-entry preparations have been completed.
Before an employee can enter a permit space, the internal atmosphere must be tested with an instrument that detects oxygen content, flammable gases and vapours, and potential toxic air contaminants. Employers are also required to –
- Define hazards in permit spaces,
- Have a confined space entry protocol, and a written permit program, train and equip employees to complete tasks in particular permit spaces, only allow authorised entrants into the permit space, and appoint employees attendants to monitor permit space and enforce entry rules.
An attendant is an individual stationed outside one or more permit spaces whose job it is to monitor authorized entrants, as well as perform all attendant duties assigned in the employees permit space program.
Confined spaces can possess many hazards. A permit required confined space, means the confined space has one or more of the following characteristics -
- Hazardous atmosphere
- Engulfing potential
- Trapping or asphyxiated configuration
- Other recognised serious safety hazards
The atmosphere of a confined space, can be hazardous and potentially prevent escape without help or cause illness or even death. There are three types of hazards -
- Oxygen deficient
Oxygen deficiency is the atmosphere having less than normal percentage oxygen found in normal air. Oxygen is safe when it is between 19.5% and 23.5%. When the level of oxygen falls below 16%, judgement and co-ordination suffer and difficulty breathing and drowsiness occur. At 12% a person become unconscious and death occurs at 6%.
The level of oxygen can fall if the space contains iron, which uses oxygen to form rust, methane, which pushes the oxygen out of an area, and carbon dioxide which absorbs oxygen.
If employees are required to enter into an oxygen deficient confined space, they should always wear an industry approved air respirator to supply fresh, breathable air. Confined spaces may often contain gases, vapours, mists or dusts that are flammable. The risks of a fire may not be obvious and only testing can show if it contains traces of flammable substances.
Substances in the air can be ignited by –
- Grinding or welding
- Unapproved electrical equipment,
- Any kind of metal friction, or
- Static electricity
Inhalation of the atmosphere can be toxic. If a substance exceeds it permissible exposure limit, it has the potential to cause illness or death. Inhaling just a little of some substances can cause irritation to the respiratory or nervous system. Such toxins include –
- Carbon monoxide, which replaces the oxygen in the blood and can cause death.
- Hydrogen sulphide, which can cut off breathing. It can however, be easily detected by it’s rotten egg smell
- Sulphur dioxide , which is very poisonous, even in small amounts. Dizziness, drowsiness, nausea, or headaches are good signs that the confined space should be evacuated immediately
Another hazardous a confined space may have is the potential for engulfment. This happens when an employee is trapped, buried or smothered by a liquid of flowing solids, such as grain or sand.
Even if the material doesn’t cover the head, the pressure on the chest can be enough to prevent breathing or damage internal organs. Some confined spaces have an “entrapping design”. Employees can be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross section.
Confined spaces may also contain physical hazards, such as moving machinery parts, build up of heat, falls from entry or exit ladders, noise from machinery, and electrocution from live wires.
Employee training is a very important part of safety in confined spaces. It is up to each employer to maintain a safe working environment. Each employers permit required confined space safety program must ensure that all authorized entrants know the hazards of the confined space they’re about to enter, use proper equipment, communicate with the attendant as necessary and alert them whenever a potential dangerous situation or prohibited condition arises.