October 12, 2017 - 21.52
Cement-based Products and their Impact on OSHA Thresholds for Respirable Crystalline Silica
por Dan Marvin
Recently, OSHA enacted lower thresholds for worker exposure to respirable crystalline silica, causing both debate and concern within the construction industry. In response to these concerns, our hope is to give a brief overview of this rule and clarify some key points on this in-depth topic. For a more detailed discussion on 'respirable crystalline silica'
, refer to the OSHA website
What is respirable crystalline silica?
Silica (SiO2) is one of the most common components of the earth's crust. It is found in sand, rocks, and dirt. It is also a very small component of Portland cement, an ingredient in most mortars, grouts, and cement-based products. Most cement based products also contain silica sand. Only crystalline silica that is small enough (less than 10 microns) to be inhalled into the lungs is respirable silica
when it is airborne. This is similar in size to cat dander or pollen and has a similar irritating effect on the lining of the lungs. In extreme cases this can lead to silicosis or other cancers.
Click to watch the Wale Tale remove dust at the source
What isn't respirable crystalline silica?
Once a powdered product has been mixed with water, it no longer gives off significant quantities of respirable silica. It also doesn't emit respirable silica once it is cured. Likewise, common construction products like tile, bricks, and cured concrete contain silica but don't give off respirable silica unless they are dry-cut, drilled, or otherwise disturbed. Products with a similar name like Silane or Silicone are not sources of repirable silica. Paste products or pre-mixed products do not give off respirable silica. Glass contains silica but not in a crystalline form so it is also not considered respirable crystalline silica.Which products are a source?
To be a potential source of respirable crystalline silica, products must arrive in a powdered form and contain crystalline silica. This can include site-mix products (such as a 5 to 1 mud bed mix) or bagged products like mortars, grouts, patches, or levelers designed to be mixed with water. The Safety Data Sheet
(SDS) for a product lists how much overall silica the product contains. However, the size of the silica particles determine if the silica is respirable, so a product with a high percentage of washed, coarse silica may emit less respirable crystalline silica than a product with a finer grade but less overall silica. What other activities are a source?
Sweeping, transporting, and dumping of anything silica-containing such as gravel, dirt, sand, and cement can cause crystalline silica to become airborne. Cutting, grinding, polishing, drilling, jack-hammering or other activities done dry to silica-containng items such as tile, stone, concrete, bricks, and concrete blocks are another common source. All sources of potential exposure must be considered for the OSHA regulations.How do I comply with the OSHA requirement?
There are many elements to the standard and it can't be fully summarized in a few sentences. However, OSHA does provide resources
to help contractors understand the new rule. In a very general sense, the rule requires people who are paid to perform construction services to 1) understand if respirable crystalline silica exists in the workplace 2) develop a plan to communicate the potential for exposure to silica with employees and minimize risk 3) test to know if the level of silica exceeds the thresholds of the standard and 4) take action if it does. That action can be in the form of engineering controls (for example, putting dust collection at sources of dust) work practice controls (for example, wet cutting and grinding instead of dry) or personal protective equipment (for example, respirators). Are there "OSHA compliant" products?
No, OSHA isn't in the product verification business
. Any reports provided by a material supplier have been generated by that supplier. OSHA is under no obligation to accept them as proof of compliance with the regulations. There is also no requirement in the standard that materials must pass a particular test since there is no standardized way of testing how much respirable crystalline silica is emitted from a particular product. From the OSHA website: The OSHA standards do not specify the safety requirements the products must meet; these requirements are specified by U.S. standards-developing organizations.
Click to watch the Wale Tale remove dust at the source
How is MAPEI responding?
First, MAPEI has to comply with the new requirements at our factories too. We have conducted the independent, 3rd party testing required to know that our employees are below the thresholds
. Second, we have tested many of our products in worksite conditions and been active in communicating with our customers to steer them to lower silica options
if there is a concern. Finally, we encourage everyone to use best practices at the jobsite to keep dust low:
* Keep work areas clean - use wet scrubbers to remove loose dirt and dust
* Add product to water, not water to product
* Pour product slowly and as close to the water in the bucket as possible
* Use lower speeds for mixers
* Wet cut instead of dry cut
* Work in a well ventilated space, outdoors if weather conditions permit
* Use dust collection devices such as HEPA vacuums and a MAPEI branded 'Wale Tale
' available from your MAPEI salesperson. The Wale Tale clips to a 5-gallon bucket and to the hose of your HEPA vacuum to pull dust away as you pour and mix. Other dust collection devices are also available that connect directly to the tools you use.
Respirable crystalline silica is a concern, but arming yourself with knowledge is the best way to know that you and your employees are protected.