Each year, the month of May brings nice weather that reminds us that the new summer season is just around the corner. The leaves appear on the trees, the grass begins to grow and bicycles, kayaks and golf clubs get moved to their rightful place at the front of the garage. We look forward to opening the cottage, summer barbeques and spending quality time with family and friends.
If you follow our blog, you know that I’ve recently written a couple of articles on occupational dust exposure, including The Worst Jobs for Your Lungs and How to Measure Dust in the Workplace. Today, I want to focus in on one in particular: crystalline silica.
Here are some things you need to know about this naturally-occurring substance, its negative health effects and how you can successfully monitor it in your workplace.
Where does crystalline silica come from?
If you work in construction, you’re no stranger to working around dust that contains silica. In fact, many of the materials you see at a site likely include either naturally-occurring or man-made sources of the mineral. These include concrete, granite, sand, brick, stone and mortar. When you cut, saw, grind, crush or drill these materials, millions of tiny particles can be dispersed into the air.
How long does silica dust stay in the air?
It depends on the particle size and activity involved. Is your work environment:
- Well ventilated?
These are all factors that determine how long silica particles can stay airborne. While it’s difficult to determine how long silica particles can last in the air, it’s known that they can stay suspended in the air for days and travel long distances.*
Is silica dust bad for you?
Those exposed to crystalline silica are at increased risk of developing serious illnesses including silicosis, lung cancer, and chronic obstructive pulmonary and kidney disease.
Silicosis is caused when crystalline silica particles (less than 10 microns) are inhaled. These tiny particles can embed themselves in the lungs, causing scar tissue to form which can lead to difficulty breathing. A whopping 56 per cent of silicosis cases are from those who work in the construction industry. Other at-risk occupations include mining, masonry, demolition, painting, and glass or metal manufacturing.
What are the exposure limits for silica?
The permissible exposure limit (PEL) for respirable crystalline silica is 50 μg/m3, averaged over an eight-hour day. The action level, over which activities like exposure monitoring and medical surveillance are required, is 25 μg/m3, averaged over an eight-hour span. Additional guidelines exist for task and industry-specific occupations based on materials used, control methods and environmental conditions; all of which should be included in a written exposure control plan developed and maintained by organisations with known crystalline silica hazards.
How do you monitor silica dust?
Approved sampling methods developed by NIOSH, OSHA and MSHA exist for crystalline silica sampling. Sampling involves the use of a pump to collect a sample onto a filter that can be sent to a lab for analysis. The chosen method will guide you through:
- Choosing the right sampling pump
- Flow rate
- Sample time
- Cyclone and filter /cassette selection
- Analysis method
Analysis of these samples must be conducted by laboratories following specified quality control procedures.
As always, it’s important to consider the when working in the presence of crystalline silica.
If you’re looking to learn more about how to measure silica in your work environment, be sure to review the recording of our Silica and Dust monitoring webinar.