A control program consists of all steps necessary to protect workers from exposure to a substance or system, and the procedures required to monitor worker exposure and their health to hazards such as chemicals, materials or substance, or other types such as noise and vibration. A written workplace hazard control program should outline which methods are being used to control the exposure and how these controls will be monitored for effectiveness.
Selecting an appropriate control is not always easy. It often involves doing a risk assessment to evaluate and prioritize the hazards and risks. In addition, both "normal" and any potential or unusual situations must be studied. Each program should be specially designed to suit the needs of the individual workplace. Hence, no two programs will be exactly alike.
Choosing a control method may involve:
For example, in the case of a noise hazard, temporary measures might require workers to use hearing protection. Long term, permanent controls might use engineering methods to remove or isolate the noise source.
Some hazards and their controls will be specifically outlined in legislation. In all cases, the employer has a duty of due diligence and is responsible for 'taking all reasonable precautions, under the particular circumstances, to prevent injuries or accidents in the workplace'.
In situations where there is not a clear way to control a hazard, or if legislation does not impose a limit or guideline, you should seek guidance from occupational health professionals such as an occupational hygienist or safety professional about what is the "best practice" or "standard practice" when working in that situation.
A legal limit or guideline (such as an exposure limit) should never be viewed as a line between "safe" and "unsafe". The best approach is to always keep exposures or the risk of a hazard as low as possible.
The main ways to control a hazard include:
These methods are also known as the "hierarchy of control" because they should be considered in the order presented (it is always best to try to eliminate the hazard first, etc).
Controls are usually placed:
Control at the source and control along the path are sometimes also known as engineering controls (see below for more details)
Elimination is the process of removing the hazard from the workplace. It is the most effective way to control a risk because the hazard is no longer present. It is the preferred way to control a hazard and should be used when ever possible.
Substitution occurs when a new chemical or substance is used instead of another chemical.It is sometimes grouped with elimination because, in effect, you are removing the first substance or hazard from the workplace. The goal, obviously, is to choose a new chemical that is less hazardous than the original.
The table below provides some examples:
|carbon tetrachloride (causes liver damage, cancer)||1,1,1-trichloroethane, dichloromethane|
|benzene (causes cancer)||toluene, cyclohexane, ketones|
|pesticides (causes various effects on body)||"natural" pesticides such as pyrethrins|
|organic solvents (causes various effects on body)||water-detergent solutions|
|leaded glazes, paints, pigments (causes various effects on body)||versions that do not contain lead|
|sandstone grinding wheels (causes severe respiratory illness due to silica)||synthetic grinding wheels such as aluminium oxide|
Remember, however, that you need to make sure the substitute chemical or substance is not causing any harmful effects, and to control and monitor exposures to make sure to the replacement chemical or substance is below occupational exposure limits.
Another type of substitution includes using the same chemical but to use it in a different form. For example, a dry, dusty powder may be a significant inhalation hazard but if this material can be purchased and used as pellets or crystals, there may be less dust in the air and therefore less exposure.
When substituting, be very careful that one hazard is not being traded for another. Before deciding to replace a chemical/substance with another, consider all the implications and potential risks of the new material.
See the OSH Answers document Substitution of Chemicals: Considerations for Selection for more information.
Engineering controls are methods that are built into the design of a plant, equipment or process to minimize the hazard. Engineering controls are a very reliable way to control worker exposures as long as the controls are designed, used and maintained properly. The basic types of engineering controls are:
Process control involves changing the way a job activity or process is done to reduce the risk. Monitoring should be done before and as well as after the change is implemented to make sure the changes did result in lower exposures.
Examples of process changes include to:
These methods aim to keep the chemical "in" and the worker "out" (or vice versa).
An enclosure keeps a selected hazard "physically" away from the worker. Enclosed equipment, for example, is tightly sealed and it is typically only opened for cleaning or maintenance. Other examples include "glove boxes" (where a chemical is in a ventilated and enclosed space and the employee works with the material by using gloves that are built in), abrasive blasting cabinets, or remote control devices. Care must be taken when the enclosure is opened for maintenance as exposure could occur if adequate precautions are not taken. The enclosure itself must be well maintained to prevent leaks.
Isolation places the hazardous process "geographically" away from the majority of the workers. Common isolation techniques are to create a contaminant-free booth either around the equipment or around the employee workstations.
Ventilation is a method of control that strategically "adds" and "removes" air in the work environment. Ventilation can remove or dilute an air contaminant if designed properly. Local exhaust ventilation is very adaptable to almost all chemicals and operations. It removes the contaminant at the source so it cannot disperse into the work space and it generally uses lower exhaust rates than general ventilation (general ventilation usually exchanges air in the entire room).
Local exhaust ventilation is an effective means of controlling workplace exposures but should be used when other methods (such as elimination or substitution) are not possible.
A local exhaust ventilation system consists of these basic parts:
The design of a ventilation system is very important and must match the particular process and chemical or contaminant in use. Expert guidance should be sought. It is a very effective control measure but only if it is designed and maintained properly.
Because contaminants are exhausted to the outdoors, you should also check with your local environment ministry or municipality for any environmental air regulations or bylaws that may apply in your area.
Administrative controls limit workers' exposures by scheduling shorter work times in contaminant areas or by implementing other "rules". These control measures have many limitations because the hazard itself is not actually removed or reduced. Administrative controls are not generally favoured because they can be difficult to implement, maintain and are not a reliable way to reduce exposure. When necessary, methods of administrative control include:
Work practices are also a form of administrative controls. In most workplaces, even if there are well designed and well maintained engineering controls present, safe work practices are very important. Some elements of safe work practices include:
Employee education and training on how to conduct their work safely helps to minimize the risk of exposure and is a critical element of any complete workplace health and safety program. Training must cover not only how to do the job safely but it must also ensure that workers understand the hazards of their job. It must also provide them with information on how to protect themselves and co-workers.
Good housekeeping is essential to prevent the accumulation of hazardous or toxic materials (e.g., build-up of dust or contaminant on ledges, or beams), or hazardous conditions (e.g., poor stockpiling).
For more information about workplace housekeeping, please see the OSH Answers document Workplace Housekeeping - Basic Guide.
Being prepare for emergencies means making sure that the necessary equipment and supplies are readily available and that employees know what to do when something unplanned happens such as a release, spill, fire or injury. These procedures should be written and employees should have the opportunity to practice their emergency response skills regularly.
Please see the OSH Answers document on emergency planning for more information.
Personal hygiene practices are another effective way to reduce the amount of a hazardous material absorbed, ingested or inhaled by a worker. They are particularly effective if the contaminant(s) can accumulate on the skin, clothing or hair.
Examples of personal hygiene practices include:
Personal protective equipment (PPE) includes items such as respirators, protective clothing such as gloves, face shields, eye protection, and footwear that serve to provide a barrier between the wearer and the chemical or material.
It is the final item on the list for a very good reason. Personal protective equipment should never be the only method used to reduce exposure except under very specific circumstances because PPE may "fail" (stop protecting the worker) with little or no warning. For example: "breakthrough" can occur with gloves, clothing, and respirator cartridges.
No matter which type of PPE is used, it is essential to have a complete PPE program in place. For more information about PPE programs, please see the following document "Designing an Effective PPE Program".
It is important to monitor both the hazard and the control method to make sure that the control is working effectively and that exposure to the hazard is reduced or eliminated.
Some tools include physical inspection, testing, exposure assessment, observations, injury and illness tracking, employee feedback/input, occupational health assessment and other methods.
Be sure to answer the following questions:
(Adapted from the Occupational Health and Safety Committee Manual, Government of Saskatchewan)
A review will identify areas that may need more improvement or refinement. It is important to know if all workplace hazards are identified, assessed and appropriately controlled. Communication about the hazards and how to control them must be done for all employees of the organization.
Document last updated on April 20, 2006