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One size does not fit all: Thoughts on RPE
Before selecting RPE, there are various considerations ranging from the type to the duration of activities. Generally, it is far easier and more efficient to use engineering controls to protect a wider range of workers than ill-fitting RPE that may give a false sense of security and endanger the lives of wearers. (Water or on-tool extraction coupled with suitable RPE provides additional protection.)
The chosen RPE must be adequate for the amount and type of dust; it should have an assigned protection factor (APF), which is the level of protection a respirator can be expected to provide if it is functioning properly and the user is wearing it correctly. APF is scored via a number, allowing users to gage how much contaminant they are expected to inhale while wearing the respirator.
The APF is calculated by taking measurements of air samples simultaneously outside and inside the respirator as the worker continues the job. The general level for RCS dust is an APF of 40 based on the activity—this means the wearer only breathes 1/40th of the amount of dust in the air.
The RPE must also be suitable for the job. Disposable masks or half-masks can become uncomfortable to wear for long periods, whereas powered air-supply RPE helps minimize this. When people are working for more than an hour, it is also important to consider whether the RPE is compatible with other items of protective equipment. Face-fit testing can ensure it is being worn correctly (ideally, anyone using tight-fitting masks will be clean-shaven), but RPE is the last line of protection.
The correct HEPA-type cartridge should be fitted to protect workers against silica dust exposure. In North America, this tends to be magenta or purple, but one should always refer to the manufacturer’s safety data sheet or follow recommendations based on findings of air-monitoring.
Reviewing the controls
Even with all the right controls in place, they must be checked to ensure they are working properly. This means:
- having procedures to ensure work is done in the right way;
- checking controls are effective (if the work still seems “dusty,” exposure monitoring should be considered);
- involving workers, as they can help identify problems and find practical solutions;
- maintaining equipment (e.g. following manuals, inspecting for damage, making repairs, replacing masks, storing and maintaining non-disposable RPE, and testing on-tool extraction systems); and
- supervising workers to ensure they use the controls provided, follow the correct work method, and attend any health surveillance where required.
Air monitoring
Personal or background air monitoring should be carried out to accurately determine the levels of dust generation at various positions in the worksite and the maximum level of worker exposure. Monitoring will enable the correct selection of dust control methods and respiratory protection. Regular air monitoring on existing and new work methods will help ensure in-place dust control methods remain effective and provide adequate protection for workers.
Health surveillance
A health surveillance program will be important to verify controls are protecting staff. The surveillance program should be under the direction of a suitable respiratory physician and can include pre-employment health screening and occupational history questionnaires to set a baseline.
Protective clothing
It is vital dusty clothes do not contaminate cars, homes, or other areas outside of the worksite. Workers should have disposable overalls or washable clothes to change into at the site. Before leaving, workers should shower if possible and then change into clean clothes without shaking these out. Workers should not be taking dusty clothing home to wash—this may expose family to harmful levels of RCS dust. There are documented cases of family members getting sick from indirect exposures to silica dust and asbestos.
Training
Workers should be provided with competency based training on silica dust awareness. This includes information about the health effects of exposure to silica dust, work practices to follow when silica dust is created at a worksite, and the appropriate use and care of protective equipment. It is vital to ensure workers actually understand rather than just sit through the talk.
Prevention is the best form of protection against silicosis and other illnesses, by either complete elimination of the silica dust hazard or introducing suitable dust-control strategies using dry air-filtering and water spray where dust emanates. Further, each worksite needs to have a comprehensive review of the hazards covering which technique is likely to be appropriate and establishing suitable and effective risk-control measures such as development of an ECP—required in most workplaces where high levels of dust are identified.
Conclusion
Based on current medical knowledge, silicosis is not considered to be curable although therapy can alleviate some of the symptoms. It can develop within a few weeks of heavy exposure and continue even years after exposure ceases. (Smoking can also exacerbate the symptoms.) In many cases, silicosis is considered asymptomatic—a person may not show classic signs of silicosis, which is one of the reasons why misdiagnosis is widespread. Prevention of exposure is the key.
Note
1 In this incident from the 1930s, hundreds of construction workers died as a result of acute silicosis and associated conditions due to exposure of high levels of RCS dust while building a tunnel through sandstone-based rock with little (or no) respiratory protection.
Nayab Sultan is a researcher at Silicosis Research, and is currently pursuing his PhD in silicosis prevalence in North America. He holds M.Sc. and M.Phil. degrees in the science of occupational health, safety, and the environment. Sultan has nearly 30 years of experience in construction and engineering, and has worked as a subject matter expert to several organizations across the Americas. He can be reached via e-mail at nmsultan@gmail.com.
