What is Crystalline Silica

Crystalline silica is an abundant natural mineral found in soil, sand and stone consisting of three forms; Quartz, cristobalite and tridymite. Crystalline silica can become respirable when concrete, brick, mortar and other construction materials are chipped, ground, sanded, drilled or cut. Typically, respirable crystalline silica is 100 times smaller than the sand found at the beach. When inhaled, these particles can penetrate deep into the lungs.

The primary exposure route for respirable crystalline silica, is through the use of quartz containing products or raw materials. In the construction industry, the most common high exposure activities include abrasive blasting with sand; sawing brick or concrete; sanding or drilling into concrete walls; grinding mortar; manufacturing brick, concrete blocks, stone countertops, or ceramic products; and cutting or crushing stone.

What are the hazards associated with crystalline silica?

Continued exposure to respirable crystalline silica can lead to severe recognized health hazards:

Silicosis: Dust entering the lungs can cause the formation of scar tissue buildup making it difficult for the lungs to bring in oxygen. Extended exposure to respirable silica can increasingly damage lung tissue leading to shortness of breath, fatigue, chest pain, and respiratory failure. There is no known cure for silicosis.

Lung Cancer: Studies have shown strong links between human lung cancer and exposure to respirable crystalline silica, specifically in quarry and granite workers, and workers involved in ceramic, pottery, refractory brick, and certain earth industries. 

Chronic Obstructive Pulmonary Disease: Exposure to respirable crystalline silica increases the risk of other lung diseases, primarily COPD, which includes emphysema and chronic bronchitis. The main symptom of COPD is shortness of breath. COPD is not usually reversible and may worsen over time.

Kidney Disease: Increased exposure to respirable crystalline silica has led to higher incidence of kidney disease and kidney failure; particularly with sand blasting workers.

OSHA’s Crystalline Silica Rule

On March 24th, 2016 the Occupational Safety and Health Administration (OSHA) published its final rule amending its existing standard for occupational exposure to respirable crystalline silica. The final rule establishes a permissible exposure limit (PEL) for respirable crystalline silica at 50 μg/m3 as an 8-hour time-weighted average (TWA). The rule applies to all occupational exposures to silica at a construction worksite, except where employee exposures remain below 25 μg/m3. Additionally, the rule establishes provisions to protect employees including requirements for exposure control methods, exposure assessments, work practice controls, respiratory protection, medical surveillance, hazard communication, and recordkeeping requirements.

OSHA Silica Rule – Summary Update

Exposure Control Methods

Construction employers are required to implement appropriate engineering controls, work practices and respiratory protections to protect their employees. The OSHA Respirable Silica Rule allows for two methods of reducing worker exposure to silica; “specified exposure control methods” and “alternative exposure control methods.” 

Under the specified exposure control method, employers can comply with the rule by implementing the requirements for a specific task outlined in “Table 1” of 29 C.F.R. § 1926.1153(d). Table 1, lists a variety of construction tasks with known risks of silica exposure. Each task contains relevant engineering controls, work practices and respiratory requirements for a given time period of exposure. Employers using Table 1 are not required to perform compliance monitoring or worker exposure assessments.

If employers choose not to use Table 1 they must use an alternative exposure control method to comply with the rule. Under this option, employers can design their own methods and practices to reduce worker exposure; however, they must demonstrate compliance with the PEL of >50 μg/mby performing a worker exposure assessment or periodic exposure monitoring of the work site.


Employers are required to follow proper housekeeping requirements to minimize the worker exposure to respirable dust. Employers must not allow dry sweeping or dry brushing on worksites where such activity could lead to employee exposure to respirable crystalline silica unless other methods that minimize the likelihood of exposure are not feasible (e.g. wet sweeping, HEPA-filtered vacuuming). Additionally, employers must not use compressed air to clean a worksite, unless the worksite uses a ventilation system that captures the compressed air, or alternative measures are not feasible.

Written Exposure Control Plan

The employer shall establish and implement a written exposure control plan that includes the following 4 items:

  1. A description of all tasks that involve exposure to respirable crystalline silica
  2. A list of the engineering controls, work practices and respiratory protection requirements for all relevant tasks
  3. A description of the housekeeping measures used to limit worker exposures
  4. A description of the procedures used to restrict access to work areas, when necessary, to minimize the number of employees exposed to respirable silica

The employer must nominate a competent employee to manage, update and implement the written exposure control plan. The individual will be responsible for training relevant employees and performing regular worksite audits.

Medical Surveillance

The OSHA Silica rule requires construction employers to provide medical surveillance at no cost, and at a reasonable time and place to any employee who is required by the silica standard to use a respirator for 30 or more days a year. Medical examinations and procedures must be performed by a licensed health care professional, with the initial surveillance occurring within 30 days of an initial assignment. Follow-up medical examinations must occur on a three-year rotation.

All examinations must include a medical and work history, a physical examination, a chest x-ray, a pulmonary function test, a test for latent tuberculosis infection (initial exam only), and any other tests deemed appropriate by the licensed medical professional. All employees subject to a medical examination are entitled to receive: written results of the medical examination, recommendations on the limitations of an employees’ respirator use, recommendations on the employee's exposure to silica, and, if applicable, advice to see a specialist.

Finally, the employer shall receive a written report from the licensed medical professional 30 days after the medical examination that indicates the date of the examination, that the exam covers the requirements of the standard, and the recommended limitations of respirator use.

Employee Education and Training

Employers must ensure that each employee covered under the silica rule understands the health hazards associated with respirable silica, the worksite tasks that can lead to elevate silica risks, and the control measures used to mitigate worker exposure.


Employers are required to create and maintain data relevant to compliance with the silica rule. All information must be maintained for a period of 30 years.

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