7 February 2017
Written by Terry Gorman
As you may know, overexposure to particles, fumes, gases and vapours can have serious health consequences if not assessed and controlled appropriately. Workplaces are regulated to provide a safe place of work and need to control and limit exposure.
What many workers are not aware of is that there can be significant risk from overexposure to silica in industries like construction, tunnelling, mining and others.
What is silica and its impact?
Silica is a very common mineral found in the earth’s crust. The crystalline form of silica is commonly known as quartz. In workplaces, silica is found in cement, brick, concrete, pavers, sandstone, granite, terracotta tiles and other common building products. When you cut, abrade, drill or rip up products containing silica, this can produce airborne silica particles that can be so fine you may not be aware that you’re inhaling them.
Ongoing exposure over years of work will add up and the damage caused by the silica on the lungs may not be evident for many years. All workers with exposure to silica particles need to take appropriate steps to control exposures. Use of wet cutting techniques or extract ventilation may be the solution, but respiratory protection is commonly required where other controls are not available or suitable.
Our lungs contain some protective mechanisms including scavenger cells called macrophages. The job of these cells is to engulf, dissolve and remove dust particles (including silica), but there can be situations where there is simply too much dust.
The capacity of the lungs to capture and remove these particles can be overrun, leaving particles in the lungs for long periods resulting in damage and scarring of the lungs. Symptoms of silica overexposure include shortness of breath, chest pain, loss of appetite, a persistent cough and fatigue. More severe impacts of silica could be chronic bronchitis, silicosis, kidney damage and even lung cancer.
Prevention is better than cure
Long term lung damage can be prevented through use of appropriate controls which can include use of safety equipment like disposable respirators. Of course, these must be used and fitted correctly as they rely on an effective faceseal to protect. Improper or poor fitting due to facial hair/stubble allows small gaps to form between the respirator and the skin, which allows contaminants to reach the airways and lungs. Male employees must be clean-shaven at the start of their work shift. Long hair should be tied back and jewellery removed so that it doesn’t interfere with the face seal.
Respirators will be more comfortable to use when the breathing resistance is low. The effects of higher breathing resistance can include increased physical effort, sweating and heat build-up. Sharp head movements and sweat can cause the respirator to move on the user’s face, compromising the fit. As the particle filter loads up with contaminant, it becomes harder and harder to breathe through. At some point the wearer will decide the resistance is too high and breathing too difficult – it is then time to change the filter.
Choosing a disposable respirator
The most common reason workers do not wear the safety equipment provided is when it’s uncomfortable and hampers their efforts to do their job.
This means it’s important to choose an appropriate respirator that does the job required, has low breathing resistance, is comfortable to wear and fits the wearer to provide suitable protection.
Some features to look out for when choosing a disposable respirator:
? An exhalation valve to reduce heat build-up and minimise fogging of eyewear.
? Sculpted nose panel and soft surfaces to promote an effective, comfortable face seal.
? Designed to fit most face shapes and sizes.
Proper fit and training
All tight fitting respirators (disposable or reusable, half face or full face masks) need to be fit tested on the individual wearer to ensure the mask fits effectively (ref. AS/NZS 1715). 3M sells qualitative fit test kits which work by spraying a sweet or bitter solution into the breathing zone of the test subject wearing the selected respirator. If the wearer does not taste the spray while doing a set of simple exercises, they pass the fit test for that specific respirator model. If they have a poor fit and there is enough leakage, they will taste the spray and that mask is deemed not suitable for that individual – another model should be tried and tested until a pass is achieved. There is a published, established protocol describing how to perform a fit test, with clear instructions provided in the fit test kit.
All workers using respirators need initial and ongoing training on how to effectively fit and maintain the masks they use. Get in touch to discuss onsite training at firstname.lastname@example.org
About the Author
Terry Gorman is a Senior Occupational Hygienist in the Personal Safety Division at 3M.