Sunday | February 18, 2018

Here’s How New Silica Exposure Limits Affect You

The vacuum control system (VCS) on milling machines is designed to direct any airborne dust into a bag or reservoir without increasing demand on the machine’s engine. Photo courtesy Bomag.

As of January 2017, large milling machines for half-lane or full-lane milling are required to include vacuum control systems and enhanced water spray systems. Bomag Americas is one of the companies th... [Full View]

As members of the asphalt industry wrapped up the largest trade show event of the year March 24, the Occupational Safety and Health Administration (OSHA) issued its final rule on silica standards. Reducing the permissible exposure limits (PELs) to crystalline silica was the first revision OSHA had made to the standards in more than 40 years, and goes into effect June 23, 2016.

The ruling didn’t take the asphalt industry by surprise. As we’ve reported in the pages of AsphaltPro before, milling machine original equipment manufacturers (OEMs), members of the National Institute of Safety and Health (NIOSH), and members of the National Asphalt Pavement Association (NAPA), worked together as the Milling Machine Partnership to research just what levels of crystalline silica dust workers might be exposed to, and just how to reduce that exposure for the optimum working environment.

Howard Marks is the vice president for environment, safety and health with NAPA, and shared with attendees of a webinar on legislative and regulatory issues April 5 that the association was successful in soliciting milling operations relief on two key areas thanks to the work of the Milling Machine Partnership. The language regarding respiratory protection and visible emissions as it pertains to milling operations was removed from the final silica rule, Marks explained. This was possible because industry was able to provide fact-based information to OSHA regarding exposure levels, and the common-sense engineering controls solutions OEMs have worked to include on equipment. Let’s take a closer look at the final rule and its impact on business.

The new ruling from OSHA sets the PEL per eight-hour work shift at 50 micrograms per cubic meter of air. Employers in the construction sector, such as those with workers employed in a milling operation, have until June 2017 to comply. Employers in the general industry (and maritime), such as those operating an asphalt plant or quarry, have until June 2018 to comply.

large milling machines

As of January 2017, large milling machines for half-lane or full-lane milling are required to include vacuum control systems and enhanced water spray systems. Bomag Americas is one of the companies that participated in the Milling Machine Partnership and already offers the VCS and enhanced water spray for customers. Photo courtesy Bomag.

The National Law Review released a summary of the silica ruling March 30 that explained the two standards have key provisions that appear in both. From the National Law Review paper:

“Although OSHA issued two standards—one for the construction industry and another for general industry and maritime employers—certain key provisions appear in both standards, including:

  • Reducing the PEL for respirable crystalline silica to 50 micrograms per cubic meter of air, averaged over an 8-hour shift;

  • Requiring employers to use engineering controls and practices to keep worker exposure at or below the PEL, such as wetting down work operations, using vacuums to keep silica dust out o the air, and limiting worker access to high exposure areas (note: providing respirators is only allowed when engineering controls cannot adequately limit exposure);

  • Requiring employers to develop a written exposure control plan, offer medical exams to highly exposed workers, and train workers on silica risks and how to limit exposures;

  • Mandating that employers keeps records of workers’ silica exposure and medical exams;

  • Providing flexibility to help employers—especially small businesses—protect workers from silica exposure by offering compliance alternatives.”

NAPA staff explained that engineering controls are only required to exempt employers from some of the rule obligations, such as monitoring. If you elect not to implement engineering controls, you will be required to conduct an exposure assessment and prepare a plan of action for exposures at half the PEL level, according to NAPA information. NAPA’s interim guidance document states, “Under the rule, employers must be cognizant of and/or determine whether their employees have the potential for exposure to airborne silica. Specifically, an employer must perform an initial exposure assessment or monitor employees ‘who are, or may reasonably be expected to be, exposed to airborne concentrations of respirable crystalline silica at or above the action level.’” That document is available from NAPA’s EH&S advocacy team.

OSHA has a list of engineering controls it has approved for equipment and activities that apply to our industry. Visit to view Table 1 of the standard. If a particular activity in your company or on your job site doesn’t include the engineering controls that OSHA has approved, you will have to follow a number of steps to be in compliance with the new ruling. First, conduct an exposure assessment for the activity. Second, determine if the employee performing the task will be above one-half of the PEL. Third, determine how to lower his exposure level for the task. Visit the NAPA Silica Rule Interim Guidance document for additional information.

Not all members of the construction or general industries found the new standard acceptable. As of press time, eight construction industry organizations—the American Subcontractors Association of Texas, Associated Masonry Contractors of Texas, Distribution Contractors Association, Louisiana Associated General Contractors, Mechanical Contractors Associations of Texas, Mississippi Road Builders’ Association, Pelican Chapter of Associated Builders and Contractors, and Texas Association of Builders—had filed a petition for review of the rule with the U.S. Court of Appeals for the Fifth Circuit on the grounds that the proposed PEL is technologically and economically infeasible. According to the National Association of Home Builders (NAHB), the American Road and Transportation Builders Association (ARTBA), American Subcontractors Association, Associated Builders and Contractors, the Associated General Contractors of America, Mason Contractors Association of America, Mechanical Contractors Association of America, and NAHB are joining the petition. During the webinar April 4, NAPA staff indicated that association was not inclined to join the petition at this time.

NAPA’s interim guidance summarizes the situation concisely for asphalt professionals.

“The final silica…standard is more than 600 pages of background information and regulatory criteria….The silica rule can be summarized quickly as follows:

  • Each employer is required to understand potential employee exposure to airborne crystalline silica and required to ensure an employee’s exposure is below the PEL;

  • OSHA has approved certain control technologies in various (construction) activities that, if used, will exempt the employer from some additional requirements under the silica rule (e.g., the necessity to conduct an exposure assessment); and

  • There are certain aspects of the rule that all employers will need to follow (e.g., Hazard Communication), regardless of whether they use equipment with OSHA-approved controls.”



Does OSHA’s Silica Rule Affect Me?

“Yes. In the road construction, paving, and asphalt production industries, the primary source of airborne crystalline silica exposure occurs from fracturing aggregate or rock. Job tasks and activities with a potential for airborne silica exposure can range from monitoring aggregate crushing operations to operating a front-end loader when transferring aggregate piles to hauling materials over gravel roads. Other potential exposure activities include baghouse and drum maintenance, roadway sweeping, and milling operations, as well as roadway saw-cutting activities. The final rule…applies to employees working on road construction sites and at asphalt pavement mix facilities. The rule is codified at 29 CFR 1926.1052 for general industry and at 29 CFR 1926.1153 for construction activities.”

Source: NAPA’s Silica Rule Interim Guidance


About Author

Sandy Lender

Sandy Lender is the editor of AsphaltPro Magazine and part of the team that originated the how-to information concept in asphalt industry publishing. She holds an English degree from Truman State University in Missouri, but lives in sunny Florida where her spare time allows her to write fiction and help with sea turtle conservation on the side. Find her on Twitter, LinkedIn, and anywhere Google takes you...

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