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Safety Solutions at Work would like to address a serious problem that we are witnessing in industries across the province.

Employers are asking their workers to wear respirators as personal protective equipment.  However, the respirators are being assigned without fully understanding the hazards involved.  This newsletter explores the importance of occupational hygiene testing in order to properly manage the risk of workers being over-exposed to dangerous substances.

Here is some background into how companies should control exposure to dangerous substances: The Hierarchy of Hazard Control.

Hierarchy of Hazard Control

The diagram below shows the control hierarchy, with the more preferred measure on top.

1.  Elimination of Hazard, which 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.

2. Substitution, which refers to substituting the hazardous chemical/industrial process with a less hazardous one. Replacing currently used chemicals with  less toxic ones is an important part of  industrial evolution.  

   Here is an interesting example: Diacetyl was previously widely used to provide the buttery flavouring to popcorn. Twenty years ago, epidemiology studies and case reports revealed its effect of reducing lung function among popcorn making workers. Nowadays, 2,3-pentanedione is used as a safer substitute for diacetyl to produce butter-flavoured popcorn. However, substitution is not on the top of the hierarchy, because no chemical is absolutely safe. In the example of popcorn flavouring, more recent studies revealed that 2,3-pentanedione will reduce lung function as well.  Ongoing monitoring of all chemicals is essential.

3. Engineering controls are the methods that are built into the design of a plant, equipment or process to minimize the hazard. Examples would be process control, LEV (local exhaust ventilation) and hazard isolation.

4. Administrative controls  limit workers’ exposures by scheduling shorter work times in contaminant areas or by implementing rules and company policies to reduce either the time or the number of workers being exposed. The efficacy of administrative controls is subject to a variety of human factors.

5. PPE is on the bottom of the control hierarchy, which means it is the least preferred method. Personal protective equipment (such as respirators) should never be the only method used to reduce exposure. The reasons this are further explained below.

Limitations of PPE

• PPE may fail with little or no warning. For example: “breakthrough” can occur with gloves, clothing, and respirator cartridges, and the consequence of relying on it as the sole way of control could be catastrophic. Air-purifying respirators cannot be used for gases and vapours with poor warning properties, especially when end-of-service-life indicator is not available. Air-supplying respirators, on the other hand, although supply clean air from air tank or compressor, have limited mobility and require a larger purchasing/maintenance budget.

• The absorbing material inside cartridges and filters of air-purifying respirators may not be efficient for certain contaminants. Examples of such contaminants are nitrogen dioxide, nitric oxide and nitrous oxide.

• There is an assigned protection factor (APF) for each specific respirator.  Air-purifying respirators for example,  have an APF of 10 to 50. An APF of 10 to 50 means that if the respirators were fit tested, being worn properly by the worker and not being broken through, the theoretical exposure level that the worker is expected would be 1/50 to 1/10 of  a worker who is unprotected. However, the actual protection efficiency may not be achievable, due to the various human factors. For example, the APF will be reduced if workers are not clean shaven.  Getting men to shave every morning is no easy task!

Necessity of Exposure Assessment

WorkSafeBC OHS Regulation mandates the following workplace monitoring procedures:

• When a worker is or may be exposed to a hazardous substance, the employer should ensure that a walkthrough survey is conducted to assess the potential for overexposure taking into account all routes of exposure.

• If the walkthrough survey reveals that a worker may be at risk of overexposure to an airborne contaminant, the employer must ensure that air sampling is conducted to assess the potential for overexposure. 

• Additional workplace monitoring to reliably determine worker exposure is required if a worker may be exposed to an air contaminant in excess of 50% of its exposure limit.

Currently, WorkSafeBC regulates the maximum allowable exposure level for around 800 substances. It is the employer’s responsibility to ensure that the workers are not exposed to levels higher than indicated by WorkSafeBC Exposure Limit. Only by doing a hygiene testing can you make definitive conclusions. A complete list of these substances and exposure limits can be found in G5.57 of WorkSafeBC OHS Guidelines.

In addition to meeting the WorkSafeBC regulation requirements, conducting air quality testing can also provide you with the following key information:

• The assigned protection factor (APF) for a disposable facial mask is 5 for single use facial mask, and is 50 for air-purifying half mask. If the workplace is heavily contaminated (i.e. above 5 times of Occupational Exposure Limit), the use of respirators, even under ideal conditions, will fail to provide workers with sufficient protection.

• Air quality testing should be conducted before and after  installing  engineering controls, to evaluate its efficiency.

• Each year WorkSafeBC receives claims of occupational disease claims. Conducting  industrial hygiene testing and documenting the report could demonstrate the employer’s due diligence in recognizing and evaluating workplace hazards.