The United States Department of Labor, Occupational Safety and Health Administration (“OSHA”) has proposed a new rule seeking to protect workers from exposure to respirable crystalline silica (“Respirable Silica”), which is released into the air when workers cut into silica-containing materials, such as rock, concrete, and mortar.  According to OSHA, occupational exposure to Respirable Silica can potentially lead to lung cancer and the development of kidney and autoimmune diseases.  Although not yet final, the proposed rule requires serious consideration by the construction industry, as it would require employers to implement considerable measures to monitor and protect workers from exposure.

Proposed Rule

The new rule proposed by OSHA is based on the Occupational Safety and Health Act, 29 U.S.C. §§ 651,et seq., and results from a preliminary determination that workers who are exposed to the current permissible exposure limits (“Exposure Limits”) of Respirable Silica face significant risk to their health.  OSHA based its determination on a review of the literature on the adverse health effects associated with exposure to Respirable Silica.  OSHA has also developed estimates of the risk of silica-related diseases based on exposure over a working lifetime at the current as well as the newly proposed Exposure Limits.

OSHA currently enforces Exposure Limits for Respirable Silica in general industry, shipyards, and construction.  The current Exposure Limits were adopted in 1971 and have not been updated since.  The limit for quartz, the most common form of Respirable Silica, is currently 250 micrograms per cubic meter of air (250 μg/m3).  The current limit for two other common forms of Respirable Silica (cristobalite and tridymite) are 125 micrograms per cubic meter of air (125 μg/m3).  The new Exposure Limits under the proposed rule would be set at 50 micrograms per cubic meter of air (50 μg/m3) for all three of these forms of Respirable Silica.  This substantial decrease in silica concentration amounts to a 400 percent reduction in current levels of allowable exposure.

In addition to the new Exposure Limits, the proposed rule would create supplementary protections for workers who are exposed to Respirable Silica, by requiring employers to monitor the amount of Respirable Silica workers are exposed to, limit workers’ access to high-risk areas, offer medical exams to certain workers, and keep records of workers’ exposure and medical exams.

Significantly, OSHA’s proposed rule would require employers to actively implement engineering controls to protect workers from exposure unless doing so would be “technologically and economically” infeasible.  Such engineering controls would include integrated water delivery systems and dust capturing devices.  According to OSHA, the proposed rule is estimated to prevent approximately 700 fatalities and 1,600 silica-related illnesses annually once it is fully effective.  The estimated cost of the rule across all industries is expected to be approximately $640 million annually.

Potential Impact On The Construction Industry

According to OSHA, the construction sector accounts for almost six percent of the nation’s total employment.  The agency has also determined that approximately 1.8 million workers are currently exposed to Respirable Silica in construction workplaces and over 650,000 of those workers are estimated to be exposed to levels exceeding OSHA’s current Exposure Limits.

As discussed, the Exposure Limits under the proposed rule would be drastically lower than the existing limits, impacting how the construction industry addresses Respirable Silica exposure.  Exposure in the construction industry typically occurs where workers are using masonry saws, grinders, and jackhammers, or engaging in earthmoving and tunneling. More specifically, OSHA has identified the following construction activities, by job category, as being potentially affected by the proposed rule: abrasive blasters; drywall finishers; heavy equipment operators; hole drillers using hand-held drills; jackhammer and impact drillers; masonry cutters using portable and stationary saws; millers using portable or mobile machines; rock and concrete drillers; rock-crushing machine operators; tuckpointers and grinders; and underground construction workers.

Under the proposed rule, construction employers may have to significantly increase their reliance on engineering controls to decrease workers’ exposure to Respirable Silica.  OSHA has made clear that it does not consider increased reliance on respirators or respiratory protection devises as legitimate alternatives to the engineering controls called for by the proposed rule.  According to OSHA, reliance on engineering controls is preferred because engineering controls are more reliable, provide consistent levels of protection to a large number of workers, and allow for predictable performance levels.  Additionally, OSHA has indicated that the effectiveness of engineering controls does not generally depend on human behavior to the same extent as personal protective equipment, such as respirators, and that the operation of the equipment is not as vulnerable to human error.  As a result, OSHA has concluded that respirators are less reliable than engineering controls and primary reliance on respirators to protect workers is generally inappropriate when feasible engineering controls are available.

Construction industry employers have their own experience with respirators and the various engineering control alternatives identified by OSHA, and should investigate how the proposed rule would affect their businesses and workers.


The dramatic reduction of Respirable Silica called for by the new rules proposed by OSHA to protect workers looks to impose a significant burden on construction industry employers.  OSHA is currently soliciting comments to the proposed rule and the requirements will become enforceable 180 days after the final rule is adopted.  Employers would be required to implement the engineering controls called for by the current version of the rule within one year of the rule’s adoption.

Given the potential impact on the bottom line, employers are encouraged to review the proposed rules and evaluate their current methods for protecting workers from Respirable Silica.  The full text of the proposed rule can be found in the Federal Register online at  This website also provides information on how to submit comments on the proposed rules, which can be submitted until the comment period closes on December 11, 2013.