To ensure that proper controls are in place that will minimize hazards, a ranking of potential controls is used, known as the hierarchy of controls. Using this hierarchy of controls provides a tiered approach to evaluating and reinforcing your safety system. The order of control preference is: Eliminating the hazard from the operation, the method, the material, and/or the structure of the facility. It at all possible, you want to avoid the hazard. Abating the hazard by limiting exposure or reducing its risks by substituting a less hazardous material, methods, etc. Controlling the hazard or redesigning and engineering the hazard out of the process. The hazard still exists, but mechanisms are in place to contain it. Using administrative methods to advise, warn, train, alert, etc., that the hazard exists and that designated safety controls are to be used. Utilize PPE only as a last resort to shield employees against hazards.
The hierarchy of hazard control has five levels, with those at the top of the list being the most effective. They can be summarized as:
- Eliminate the hazard
- Substitute a less hazardous material or process
- Engineering controls
- Administration controls
- Personal protective equipment
Eliminate the Hazard
There is no better hazard control option than eliminating the hazard. A commonly used example of eliminating a hazard is a situation in which employees are working at a height above the ground level. Moving the work to ground level eliminates the fall hazard.
Hazards may be eliminated by changing how or where the work is done. For example, by eliminating a step the process that involves a hazardous material. They may also be eliminated by redesigning a process to eliminate the use of hazardous equipment, machines, tools, or materials.
Substitution is a form of hazard elimination, and the two may be combined on some hierarchy of hazard control lists. Substitution involves replacing something that is hazardous, with something that is not hazardous. A typical example is replacing a solvent-based paint with a water-based paint. This eliminates the harmful fumes and flammable vapors that result from using, and cleaning up after using a solvent-based paint.
Care must be taken to ensure a new hazard is not introduced into the workplace when substituting one material for another.
When a hazard cannot be removed through elimination or substitution, the next best option is to use engineering controls. In this case the hazard is not eliminated, but workers are protected from the hazard. The basic idea is to design the work environment, and the work to be done, such that exposure to hazards is eliminated or reduced. For example, if a machine has moving parts, a guard may be added to prevent physical access to the moving parts.
Guarding moving parts is often referred to as “enclosure and isolation.” Other examples of enclosure and isolation include:
- Placing MCCs in a separate room – separates workers from arc flash hazards.
- Using curtains around locations where welding is taking place – protects workers from the intense light.
- Placing barriers around fans and other noisy equipment – reducing sound levels.
- Fencing around electrical switch gear – prevents access to high voltage equipment.
Engineering controls are also used to remove a hazard. A common example of this is using a fume hood to contain and remove airborne hazards.
Administrative controls are used to direct people to work in a safe manner. They include procedures, warning signs and labels, and training. Administrative controls do not eliminate hazards, but restrict access to those hazards through the use of procedures and rules.
OSHA divides these types of controls into two categories, safe work practices and administrative controls. OSHA defines safe work practices as:
Safe work practices include your company’s general workplace rules and other operation-specific rules. For example, even when a hazard is enclosed, exposure can occur when maintenance is necessary. Through established safe work practices, employee exposure to hazards can be further reduced.
OSHA considers administrative controls to be those other measures, other than work practices, used to reduce employee exposure to hazards. This includes measures such as additional relief workers, exercise breaks, and rotation of workers. The controls OSHA defines as “administrative controls” are normally used in conjunction with other controls that more directly prevent or control exposure to the hazard.
In general, administrative controls include:
- Limiting the amount of time someone is exposed to hazards.
- Written operating procedures.
- Standards for safe work practices.
- Safety and health rules for employees.
- Alarms, signs, and labels.
- Buddy system.
- Training (and refresher training).
- Stretching and warm-up exercises
- Break policies.
Using signs and labels to warn about hazards is not only a common administrative control, it is required by OSHA. You can learn more about OSHA compliance with the “OSHA Safety Sign Best Practices Guide.”
Personal Protective Equipment
When no other option is available, personal protective equipment (PPE) is used. This is the least effective, and least desirable, method of protecting workers, and is considered as the last line of defense against hazards. If the PPE is damaged or fails, the worker will be exposed to the hazard.
Common PPE includes:
- Hard hats
- Safety shoes and boots
- Safety glasses / face shields
- High visibility clothing
Knowing, understanding, and applying the hierarchy of hazard control will result in a safer workplace. Always like to use the method that is highest on the list. Eliminating the hazard is always the best option, and using PPE the least desirable option.