Left: © Studio Peace – stock.adobe.com; Right: © Dusan Petkovic – stock.adobe.com

By: Douglas Niemtschk, Contributor

Silicosis is a disease caused by inhaling respirable silica dust. Respirable dust particles are small enough to be inhaled deep into the lungs, where they create scar tissue and can lead to breathing problems and even death. High exposure levels to these particles can result in disease in as little as five years.

Exposure occurs when the respirable silica particles become airborne when certain work activities are performed that handle materials containing silica. This occurs especially in the construction industry, where many tasks tend to include the use of saws, drills, jack hammers and abrasive blasting. Other industries that have exposure potential include:

• Mining
• Oil and gas extraction
• Stone countertop fabrication
• Foundries and other manufacturing settings
• Dentistry
• Fabrication of engineered stone (quartz) countertops

Regulatory Information

Faced with the knowledge of this hazard, OSHA promulgated the Construction Industry Respirable Crystalline Silica rule, 29 CFR 1926.1153, in 2017. This regulation requires silica exposure control methods to be used in specific construction tasks where exposure levels can’t be kept less than 25µg/m3 as an 8-hr, time weighted average.

Tasks include the use of tools to cut, grind or drill material containing silica. Examples of these tools include:

• Saws
• Drills
• Grinders
• Jackhammers
• Chipping tools

Even though your facility may not be considered a construction site, tasks that use these tools to handle silica-containing material will likely trigger the applicability of the construction industry standard, because they are typically used to construct, alter or repair the facility. This is how OSHA defines “construction work.” Many facilities have maintenance personnel or contractors that use these types of tools.

According to OSHA, if you use one of these tools or perform certain tasks that generate dust when handling silica containing materials you have two options:

• Implement the required engineering, work practice and respiratory protection controls listed in the standard; or
• Perform an exposure assessment that shows exposure levels less than 25µg/m3 as an 8-hr, time weighted average.

Implementing Control Measures

Let’s look at the control measures first. One engineering control is the use of wet methods. This typically involves the use of an integrated water-delivery system that is attached to the tool. Many handheld power saws come equipped with these systems. The system directs a continuous stream of water onto the blade, thus minimizing dust production.

Another engineering control is the use of a dust collection system. These systems are made by the tool manufacturer and attached to the tool. They capture any dust that is generated through suction and filter it through a HEPA filter. All dust controls must be operated and maintained in accordance with the manufacturer’s instructions to minimize dust emissions.

Respiratory protection is typically required when working indoors or in an enclosed area—or if engineering and work practice controls are not feasible. This includes a minimum of a half-mask air purifying respirator with an N, R or P100 rating. All employees assigned to wear a respirator must be medically qualified to do so and be fit-tested. In addition, you must have a written Respiratory Protection Program.

Construction tasks where exposure to respirable silica dust is likely include use of tools to cut, grind or drill material containing silica, such as saws, grills, grinders, chipping tools or jackhammers. © Studio Peace – stock.adobe.com 

A Look at Exposure Assessment

Next, let’s look at the Exposure Assessment option. This typically means you will need to conduct air monitoring for respirable silica or have access to this type of data. It’s a good idea to consult with a certified industrial hygienist when choosing this option. They can design a sampling plan and help collect the samples.

Collecting samples involves using a personal sampling pump with appropriate media (i.e., cyclone and PVC filter) that collects air from an employee’s breathing zone. Employees with the highest exposure potential should be sampled. Once the samples are collected, the media (filter) is then sent into a laboratory for analysis. The results must be communicated to the employee within five days.

Direct-reading instruments that sample the air near the employee’s breathing zone can also be used, if the concentration of respirable silica can be calculated. Several manufacturers make direct-reading dust monitors. However, they can be quite pricey, and you may be better off renting one or hiring a consultant that can do the monitoring.

If air monitoring shows that exposures are being maintained below the action level of 25µg/m3, no further actions are needed. However, if the workplace changes (i.e., changes in how tasks are done, tools, equipment, etc.), monitoring must be repeated.

OSHA has a good publication that can help implement a silica program for your workplace. It is entitled Small Entity Compliance Guide for the Respirable Crystalline Silica Standard for Construction and can be found on OSHA’s website. The guide describes not only the engineering controls just discussed, but other work practice controls as well. For example, housekeeping is addressed. There are certain housekeeping practices that are prohibited by the OSHA Standard:

• No dry brushing or sweeping, unless wet sweeping and HEPA-filtered vacuuming is not feasible
• No use of compressed air to clean surfaces or clothing, unless the compressed air is used together with a ventilation system that effectively captures the dust cloud

The guide also addresses the development of a written exposure control plan which is a requirement of the OSHA Standard. It provides a sample written exposure control plan to help you start.

In conclusion, respirable silica is a significant hazard in the workplace. Exposures must be controlled. This means understanding and implementing the engineering and work practice controls required to minimize exposures. It also means being able to provide employees with respirators where needed. Recognize that implementing a complete respirable silica program may require help from an industrial hygienist or safety professional. IHW

[Douglas Niemtschk is a Corporate Safety Specialist at HF Sinclair. He can be reached at Douglas.Niemtschk@HFSinclair.com.]