The hierarchy of control OSHA uses to decide on precautions when hazards are identified to protect workers from harm. It is necessary to decide on the necessary precautions to control the identified hazards to bring them to an acceptable level. When trying to decide what additional precautions may be appropriate for a particular situation, a useful approach may be to use a safety control hierarchy. This post focuses on the hierarchy of OSHA-based control examples.
Hierarchy of Control OSHA explained the array as a hierarchy: Eliminating the hazard first is the preferred option. Second, if elimination is not possible, the next best option that should be preferred is called substitution. Third, if the hazards are not being controlled, then consider engineering controls. PPE is considered the least effective option.
What are the five hierarchies of control OSHA?
Where the controls at the top of the hierarchy are the most effective and those at the bottom are the least effective.
- Elimination: Physically remove or eliminate the hazard.
- Substitution: Replace the hazard.
- Engineering controls: Isolate workers from the hazard.
- Administrative controls (procedure): Change the way people work.
- PPE (behaviour): Protect the worker with personal protective equipment.
Elimination is the first preferred option in the Hierarchy of Control OSHA. If a hazard can be eliminated, then the risk created by that hazard is gone. This could be achieved by completely avoiding an activity that gives rise to a risk. For example, pipe fitting or welding activities are carried out more than 1.8 meters above the ground on a scaffolding platform. The risk of falls can be avoided if the activities are carried out on the ground.
The obvious limitation of this approach is that it is not possible to fit up/weld all pipes at ground level. But it may be possible to eliminate one or more hazards inherent in that activity. For example, one pipe is 5 meters long, so it is possible to assemble and weld 4 pipes together at ground level instead of a scaffolding platform and erect it with a crane and eliminate the risk of working at the height inherent in the 4 pipes grinding, cutting, fit-up and welding.
The use of handling aids such as wheelbarrows and lifting equipment such as gin wheels, cranes or forklifts can be used to eliminate the hazards of manual handling.
Other examples of elimination such as cleaning liquid spills, removing objects lying on the access, removing objects from heights that could fall, removing containers containing flammable liquids from a room, etc.
Substitution is the second preferred option in the Hierarchy of Control OSHA. Sometimes elimination is not possible but it is possible to substitute it with less risky material/substances or equipment. For example, a hazardous substance classified as “toxic” (lethal in small doses) is replaced by one that is “irritant”. The replacement substance is still dangerous, but much less dangerous.
In an industrial process, a chemical is used that is corrosive and toxic to workers. Therefore, this substance has been replaced by another that is not harmful or poses less risk and does not alter the process.
A piece of equipment produces emissions of toxic and flammable gases, due to the risk it represents, the company has decided to replace the equipment with a more recent model with a technology that prevents the emission of such dangerous gases.
A handling aid, such as a sack truck, does not eliminate manual handling, but it does reduce the risk of injury associated with manual handling. Replacing defective equipment and tool is also a substitution.
Engineering control is the third preferred option in the Hierarchy of Control OSHA. Engineering controls involve the use of an engineering solution to prevent exposure to hazards. The goal here is to physically isolate the hazard so no one is exposed to it. This could be done by total enclosure or containment of the hazard, for example, total enclosure of a dust-generating process to prevent its escape, acoustical enclosure of a noisy machine to reduce noise exposure to people nearby or guards around moving machinery to avoid contact.
Simply by placing the hazard in an inaccessible place. An example would be a high-noise diesel generator that can be placed outside the workshop. In this case, precautions must be taken to ensure that safety distances are maintained at all times.
Safety devices and features ensure that the item is used in the correct way and not in an unsafe way. For example, interlock switches are installed on moving machinery guards to ensure that when the guard is open, the machine will not run (but when the guard is closed, it will).
Guards to protect rotating parts of equipment, ventilation and extraction of dangerous atmospheres, placement of flanges, placement of a cover or railing around an opening, etc. are also engineering control examples.
Administrative control is the fourth preferred option in the Hierarchy of Control OSHA. Administrative controls are those that are based on procedures such as formal job safety analysis or risk assessment. This is a formal procedure that defines the hazards and risks associated with them and decides on control measures. Safe systems of work are necessary when hazards cannot be physically eliminated and some element of risk remains.
This applies to any task that involves significant risk. Certain high-risk work activities may be controlled by a permit-to-work system as part of the safe work system.
If the degree to which a worker is exposed to a hazard can be reduced, then that worker is much less likely to have an accident with that hazard. For example, a field safety officer who spends all day monitoring the area of a fin fan (loud noise) is more likely to experience hearing loss than a safety manager who only spends an hour of their workday exposed to high noise. The less time and less frequently, the better.
Many workplace health hazards cause a degree of harm that is entirely dependent on the dose. For example, hearing damage caused by exposure to loud noise is completely determined by the intensity of the noise (measured in decibels) and the duration of exposure.
If you are exposed to the same intensity of noise for twice as long, it gives you twice the dose of noise. If you are exposed for half the time, it gives you half the dose. The noise dose determines the degree of damage: the higher the dose, the greater the damage. The dose is determined by two main factors: – The concentration, intensity or magnitude of the hazard present.
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Signalling, procedures, manuals, instructions, maintenance programs, training programs, atmospheric monitoring records, authorizations for hazardous work and personnel rotation records etc. are examples of administrative control.
Information, instruction, training and supervision: training is essential for employees to become competent. A competent employee is equipped with all relevant information and instruction and is fully aware of the dangers and the use of appropriate preventive measures.
Hierarchy Control PPE
Personal protective equipment is the fifth preferred option in the Hierarchy of Control OSHA. The personal protective equipment worn or held by a worker protects him from one or more risks to his safety or health. There are cases where none of the above control measures can be used and there are times when some of them can but the residual risk remains. If this is the case then PPE may be required. There are many different types of PPE available, such as:
- Earmuffs or plug protects from high noise
- Gloves to avoid contact with substances dangerous to the skin.
- Respiratory protection against hazardous substances by inhalation (breathing).
- Eye protection against splashes of chemicals and molten metals, mists, aerosols and dust, projectiles and radiation, including laser lights.
- A safety helmet protects from dropped and flying objects.
- Safety shoes protect against rolling and slipping hazards.
The control options explained above are established as a hierarchy. Eliminating the hazard is the most preferred option and PPE is the least preferred. Workers do not behave ideally in the workplace. They knowingly break rules and are subject to harm. Elimination is more effective and PPE is less effective.
This does not mean that PPE is not necessary or less important to protect workers. If a workplace hazard is eliminated or substituted, a new level of risk is always present because risk cannot be zero.
So workers are required to always wear mandatory PPE such as helmets, safety glasses, safety shoes, FRC (fire/flame retardant/resistant clothing considered mandatory in gas and oil or petrochemical plant) and ear plugs (high noise areas).