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On March 24, 2016, the Occupational Safety and Health Administration (OSHA) finalized its new standards for occupational exposure to respirable crystalline silica (RCS). The rule is comprised of two standards—one for Construction (29 CFR 1926.1153) and one for General Industry and Maritime (29 CFR 1910.1053 or 1915.1053)—in order to tailor requirements to the circumstances found in these sectors. Both standards took effect on June 23, 2016. Most of the requirements associated with the Construction standard were scheduled to be enforced beginning June 23, 2017, but OSHA has now delayed enforcement until September 23, 2017 while they are developing educational materials for employers and enforcement guidance for their enforcement officers. Most of the General Industry and Maritime requirements are scheduled to be enforced on June 23, 2018.

More Stringent Exposure Limits

OSHA has determined that employees exposed to RCS at the previous Permissible Exposure Limits (PELs) face a significant risk of developing silicosis, other non-malignant respiratory diseases, lung cancer, and kidney diseases. The new standards adopt a PEL of 50 micrograms of RCS per cubic meter of air (50 µg/m3) as an 8-hour time-weighted average in all industries covered by the rule and an Action Limit (AL) of 25 µg/m3. OSHA estimates that the new rule will save over 600 lives and prevent more than 900 new cases of silicosis each year among the 2.3 million workers exposed in the United States.

Affected Tasks

Many construction-related tasks are affected by the new standard, including cutting, grinding, drilling, and crushing of concrete, stone, and certain roofing materials. Many other industries are also affected, including hydraulic fracturing, brick manufacturers, shipyards, abrasive blasting, stone quarries (Figure 1), and foundries. Significant exposures may also occur in the mining industry; however, the new standards do not cover mining, which is regulated by the Mine Safety and Health Administration (MSHA) instead of OSHA.

 crystalline silica particles at stone quarry tranparent

Exposure Assessments

Both new standards require affected facilities to perform exposure assessments to determine whether workers are exposed to amounts of RCS above the PEL or the AL, although certain common construction tasks are permitted to apply controls listed in a table in the Construction standard in lieu of an exposure assessment. This exposure assessment requires employers to conduct air monitoring unless "objective data" is available to demonstrate that exposure will always be below the AL. Objective data is defined as "information, such as air monitoring data from industry-wide surveys or calculations based on the composition of a substance, demonstrating employee exposure to respirable crystalline silica associated with particular product or material or a specific process, task, or activity. The data must reflect workplace conditions closely resembling or with a higher exposure potential than the processes, types of material, control methods, work practices, and environmental conditions in the employer's current operations."

The air monitoring strategy must consider all the variables affecting exposure and must use appropriate sampling devices, flow rates, and accredited laboratories. Per the new standards, RCS is defined as "quartz, cristobalite, and/or tridymite contained in airborne particles that are determined to be respirable by a sampling device designed to meet the characteristics for respirable-particle-size-selective samplers specified in the International Organization for Standardization (ISO) 7708:1995." Many traditional cyclone samplers used previously for RCS air monitoring may still be used; however, a different air flow rate may be required to achieve the specifications of the new standards. Notably, the Construction standard allows employers until June 23, 2018, to implement the new air sampling and analytical methods based on the greater differences between the new and previous methods in this industry.

Exposure Controls

crystalline silica danger signWhere exposures are determined to exceed the PEL, employers must: 1) implement all feasible engineering controls to reduce exposures that exceed the PEL; 2) provide respirators when engineering controls cannot adequately limit exposure below the PEL; and 3) limit worker access to high exposure areas. With respect to engineering controls, feasible controls must be implemented by the time each standard takes effect, except in hydraulic fracturing where engineering controls must be implemented by June 23, 2021, due to the complexities and challenges of controls in this industry. In the General Industry and Maritime standard, limiting worker access includes demarcating regulated areas (see Figure 2), requiring the use of respirators in those areas, and limiting access to authorized employees whose work duties require them to enter. In the Construction standard, an "on-site competent person" is appointed and a process must be established to restrict access and minimize the number of employees exposed to RCS.

Additional Requirements

Other provisions of the standards require employers to 1) develop a written exposure control plan; 2) implement housekeeping provisions; 3) train workers on silica risks and how to limit exposures; and 4) offer medical exams to exposed workers. The written exposure control plan must include a description of tasks that involve exposure controls used to limit exposure including engineering controls, work practices, and personal protective equipment, and housekeeping measures. This plan must be reviewed annually. Where feasible, housekeeping measures must prohibit dry sweeping or brushing of RCS containing dust and prohibit the use of compressed air to clean clothing.

Employers must also provide medical surveillance for employees exposed at or above the AL for 30 or more days per year under the General Industry and Maritime standard, or for employees who are required to wear respirators for 30 or more days per year under the Construction standard. This surveillance consists of a medical and work history questionnaire and a physical exam that includes a chest X-ray, pulmonary function test, tuberculosis test, and any other tests prescribed by the physician or other licensed health care professional (PLHCP). A baseline exam must be completed within 30 days of initial assignment to a job that qualifies for medical surveillance, and then at least every three years, or more frequently if recommended by the PLHCP. Medical surveillance in Construction must be implemented by the effective date of that standard, while in General Industry and Maritime, medical surveillance must be implemented by June 23, 2018, for employees who are exposed over the PEL and by June 23, 2020, for employees who are exposed over the AL.

Labels and Safety Data Sheets (SDSs) for products that contain RCS must comply with the existing OSHA Hazard Communication standard (29 CFR 1910.1200). The labels and SDSs must also address the key health effects of RCS including cancer, lung, immune system, and kidney effects. Furthermore, employees must be trained and demonstrate a knowledge of the health hazards of RCS, tasks in their workplace that could result in exposure, measures the employer has implemented to control exposure, the contents of the RCS standard, and a description of the medical surveillance requirements.

In summary, OSHA has implemented new rules to reduce exposure to respirable crystalline silica, which can cause debilitating and sometimes fatal conditions including silicosis. Under the rules, employers are now subject to a number of new requirements including but not limited to: 1) conducting exposure assessments; 2) implementing exposure controls; 3) developing written exposure control plans; and 4) providing medical surveillance and training for exposed worker. For more information and for assistance in meeting these new compliance obligations, please contact us at