Q&A: OSHA Regulations On Concrete Silica Dust

On September 23, the U.S. Department of Labor will begin to enforce its reduction in the amount of silica that construction workers can be exposed to over an eight-hour day.

The U.S Department of Labor will start enforcing its new concrete silica dust ruling for construction on September 23, 2017 (moved from June 23, 2017). With those new OSHA regulations coming up, it’s important to be up to date on all the new changes regarding the OSHA standards. But do facility owners and executives, and project managers know how to comply?

silica dust
Joe Nasvik

Joe Nasvik, a professional with more than 40 years of experience in the concrete and decorative concrete industries, collaborated with Bosch Power Tools to share his knowledge and insight on this issue, and the upcoming enforcement date. A member of the Decorative Concrete Hall of Fame, Nasvik served as a Bomanite contractor in the Chicago area for 20 years. He also worked in Las Vegas for several years constructing special features for casinos, including rock and waterfall features, architectural concrete, and swimming pool construction. He also served as the operations manager for a ‘start up’ precast company that held patents on concrete units used for wall construction.

Q: What is the new silica dust regulation and why is it happening?
Nasvik: When the U.S. Department of Labor issued its ruling aimed at better protecting workers from respirable silica dust, no one was surprised. Compliance with the new rule went into effect June 23, 2017, and enforcement begins September 23, 2017. The upgraded regulation substantially reduces the permissible exposure limits (PEL) for workers in the construction industry. The Department of Labor’s Occupational Safety and Health Administration (OSHA) will enforce a reduction in the amount of silica that workers can be exposed to over an eight-hour day from 250 micrograms per cubic meter of air to 50 micrograms.

Q: What exactly is silica? What kind is OSHA so concerned about?
Nasvik: Silicon (Si) is the second most common element on Earth, making up 28% of the planet’s crust. Oxygen is the most common element at 47% and aluminum is a distant third at 8%. Silicon combines with oxygen to form quartz (SiO2) — an example being sand. Silica is a component in a wide range of the Earth’s rock.silica dust

Q: Is respirable crystalline silica a threat to life?
Nasvik: Inhalation of respirable crystalline silica is a threat to life. Particles can be created by natural forces such as wind, which causes particles to collide and form smaller particles. According to OSHA, it’s estimated that 2.3 million U.S. workers are exposed to respirable silica dust at work each year.

Q: But aren’t there already OSHA regulations in place to limit silica exposure?
Nasvik: OSHA set limits on respirable crystalline silica dust exposure in 1971, shortly after the agency was created. These regulations, based on research from the 1960s and earlier, soon showed that they didn’t adequately protect workers. The limits were imposed as formulas that many people found difficult to understand. The new rule limits the amount of silica dust that workers can be exposed to on the job to 50 μg/m3 averaged over an eight-hour shift for all industries covered by the rule. That’s about 1/20th the size of a grain of salt.

Q: So what should contractors and people on the jobsite do to avoid silica dust exposure?
Nasvik: Employers are required to use “engineering controls” such as vacuum dust collection systems and water-delivery systems to limit worker exposure to respirable silica dust and use respirators as required. Specified exposure control methods are referenced in OSHA Table 1.

Q: How do I know what tools I need for the job I’m doing?
Nasvik: At the heart of the new silica dust control regulations for the construction industry is OSHA Table 1, mentioned above. Table 1 matches common construction tasks with effective dust control methods for those tasks. The table has three columns: the task or equipment being used, a column describing the method for controlling dust and a third column stating what type of respiratory protection is needed when performing the task. By finding a work activity on the table, it’s easy to determine what steps are necessary to ensure compliance.

silica dustQ: Then what’s the alternative?
Nasvik: The best way to control respirable crystalline silica dust is to remove it as it’s created. Power tool manufacturers have developed products and systems to help meet OSHA requirements for limiting silica dust exposure. For instance, Bosch’s PRO+GUARD™ dust solutions lineup are tools that provide options to assist companies and their workers remain compliant. The focus is on developing better dust extractors and attachments, such as shrouds, to capture dust at the source.

Q: How are concrete workers supposed to capture dust so it doesn’t become airborne?
Nasvik: For most concrete applications, tool attachments that confine dust are connected to vacuums to prevent particles from becoming airborne. These systems represent a primary method for keeping the air clean. Attachments include shrouds for grinders and dust extraction attachments that fit around chipping hammer bits and hammer drill bits.

Another component specifically for drilling concrete are dust extraction bits. The bit allows dust created at the bottom of a hole being drilled to be sucked through the center of the bit and collected in the dust extractor. Bosch Speed Clean™ bits are built around an internal dust channel that’s milled to deliver dust reduction in a lightweight concrete bit. These bits are both OSHA and code approved for use with epoxy anchors. In addition, employers must create processes that minimize release of respirable silica dust into the environment during maintenance of tools and employee change of work clothes.

Q: So, I just connect these accessories to my regular vacuum in the shop?
Nasvik: No. The vacuum needs to have a high amount of CFM suction (+150), a filter cleaning feature built in and it is ideal for them to be HEPA compliant. To qualify as HEPA, U.S. government standards require that the air filter remove 99.97% of particles with a size of three microns or less. HEPA filters are expensive, but necessary for removing small particles. When looking for a HEPA vacuum filter that meets OSHA requirements, it must state on the filter that it will remove particles three microns in size or less. As a filter removes smaller and smaller particles, the power and airflow of the vacuum, as measured in cubic feet per minute (cfm), must increase.

Q: How do you clean these specialty filters to make sure the vacuum still functions properly?
Nasvik: OSHA requires vacuum filters to function properly at all times. For vacuums intended for concrete/fine dust collection, certain vacs provide a feature that automatically cleans the filter every 15 seconds with reverse blasts of air (Bosch standard) to ensure the filter maintains its utility. Other manufacturers employ different filter-cleaning methods. Filters should never be washed out, especially when concrete dust is involved because it will harden in the filter pores and render the filter useless.

Q: This is a lot to digest (enforcement date is September 23). How will this affect productivity when we’re trying to finish a job?
Nasvik: The enforcement date varies by state, but for the majority September 23 is the date. This entire effort ties back to keeping people safe. There is no cure for silicosis or other silica-related diseases, so worker health depends on limiting exposure. Although regulation is sometimes viewed as limiting productivity, in this instance it can actually be enhanced. The respirable silica dust regulations require use of already accepted control methods that make implementation easier.

Read the Facility Executive post on this topic, or visit OSHA’s page on the silica dust ruling.


  1. What about the workers on milling crews. The milling machines themselves produce so much silica dust. Then the loaders trying to pick up the millings. Then the workers who are jackhammering the asphalt or concrete that has silica and finally the sweepers who are trying to clean this all up. Now what.

  2. Question: Is road and asphalt dust generated by Tractor Brooms and Sweepers considered under these new Silica guidelines? Or, is it just when cutting, drilling and grinding concrete?

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