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Silica Testing Services and Experts

Industries and employers who work with and use crystalline silica or products containing crystalline silica are required to stay within OSHA compliance (below 50 micrograms per cubic meter of air (50 μg/m3) as an 8-hour time-weighted average (TWA)) , and have a moral and statutory responsibility to provide a safe and healthy workplace with programs and to put systems in place to protect their employees from workplace hazards such as respirable crystalline silica. RHP’s assessment and exposure control services work with clients to develop programs and run audits to provide assurance of compliance with OSHA regulations and keep their workplaces healthy and safe.

With the goal of compliance of OSHA’s Permissible Exposure Limit (PEL) and Action Level (AL) concerning respirable crystalline silica, RHP industrial hygiene professionals, under our Silica Exposure Assessment and Exposure Control Services, partner with RHP clients to evaluate workplaces and employee exposures to respirable crystalline silica by measuring airborne concentrations in the breathing zones of workers and assist with post-assessment/evaluation written exposure control plans.

Risks of Silica Exposure

Inhalation of crystalline silica can lead to serious injury and in cases of excessive inhalation, fatal illness, when particles of crystalline silica become embedded in the lung. The cumulative respirable crystalline silica dose a person accumulates over time is typically calculated as an average exposure each year in mg/m3, then multiplied by the number of years, or by an estimated average for each year. As the cumulative dose increases, as does the risks of developing a silica-related illnesses such as COPD, silicosis, lung cancer, and kidney disease. Dose can vary across workers, some becoming ill after many years of low exposure levels, while other workers performing less frequent but high exposure tasks may become ill with a lower cumulative exposure.

Naturally Occurring Sources of Silica and Industries that Generate Silica Dust

Silica is a compound consisting of elemental silicon and oxygen (silicon dioxide) that can occur as both crystalline and amorphous minerals. Both crystalline and amorphous types are common substances used in construction and manufacturing for centuries.

Crystalline silica that becomes airborne as silica dust with a particle size of 10 microns and smaller is considered respirable. As a reference, particles visible to the naked eye are typically 100 microns in diameter and larger. Only very small particles of silica, less than 5 microns, are more likely to be deposited or remain in the human lung. Silica’s crystalline forms, quartz, cristobalite, and tridymite, have hazardous properties that can cause serious health effects under certain circumstances.

OSHA estimates that over 2.3 million American workers are at risk for exposure to crystalline silica. Health effects are predominantly associated with long term work related cumulative exposures, but adverse health effects may occur from very high, acute, short term exposures. Diseases connected with inhalation of respirable silica include:

  • Silicosis
  • Lung Cancer
  • Chronic Obstructive Pulmonary Disease (COPD)
  • Kidney Disease

The Agency for Toxic Substances and Disease Registry (ATSDR) toxicological profile for silica reports an estimated 3,600 to 7,300 new silicosis cases were diagnosed yearly in the US between 1987 and 1997. Silicosis mortality trends have declined over the past 50 years due to improved industrial hygiene practices and increasingly stringent regulatory standards and guidelines.

Some of the industries most effected by exposures to respirable crystalline silica include, industries involved with abrasive blasting, cement and concrete work, foundries, hydraulic fracturing in oil and gas, mining, and stone surfacing and countertop manufacturing.

OSHA’s Updated Silica Standards for Construction, General Industry and Maritime

The updated OSHA silica standards set limit (PEL) of 50 µg/m3 average over an 8-hour day and establishes a new action level (concentration of a specific substance, calculated as an eight (8)-hour time-weighted average, which initiates certain required activities such as exposure monitoring and medical surveillance) of 25 µg/m3. OSHA believes with the new lower standards they can mitigate the risks of disease due to exposures. OSHA projected that the lower PEL equal 600 less deaths associated with silica exposure and more than 900 less new cases of silicosis per year.

OSHA offers guidance to small entity employers seeking to comply with the new construction industry silica standard through the OSHA guidance document.

An important distinction between the General Industry/Maritime Standards and the Construction Standard is the inclusion of a table of tasks (Table 1), engineering controls, and respiratory protection in the Construction Standard that employers can use in lieu of measuring exposures to aid in controlling silica exposures in their workplaces. An example of a task, the OSHA-prescribed engineering control, and the required respiratory protection is illustrated in the excerpt from 1926.1153(c)(1) Specified Exposure Control Methods When Working with Materials Containing Crystalline Silica Table 1 below.

Table 1 – click to enlarge

Construction industry employers who strictly follow the OSHA guidance from Table 1 are not required to measure employee exposures. However, even though OSHA has provided Table 1 as general guidance for the construction industry, employers are still responsible to ensure the appropriate controls are in place in order to adequately protect their workers from exposures to respirable crystalline silica.

On August 22, 2018, OSHA provided a Trade Release titled, “U.S. Department of Labor Posts New Frequently Asked Questions and Videos on OSHA Standard for Controlling Silica in Construction.” The Trade Release stated that the FAQs were developed by OSHA in cooperation with industry and labor organizations. Further, a series of six new videos were developed by OSHA to instruct users on methods for controlling exposure to silica dust in workplaces when performing common construction tasks or using construction equipment. These videos cover topics including handheld power saws, jackhammers, drills, and grinders.

RHP’s Silica Exposure Assessment Services

How can an employer manage its risks and comply with OSHA’s standard? A good first step is to determine if there are potential crystalline silica exposure or over exposure sources in their operations or on their worksites. According to the general industrial hygiene hierarchy of controls for exposure of contaminates, the first consideration is the elimination of the contaminate, the crystalline silica material, if possible and substitute a less toxic substance.

Hierarchy of Controls

Most Effective




Least Effective


1. Elimination

2. Substitution

3. Engineering Controls

4. Administrative Controls

5. Personal Protective Equipment

As the elimination or substitution of silica containing materials may not be feasible, employers that use crystalline silica or products containing crystalline silica are required to comply with the new OSHA silica regulations and rely on engineering controls, administrative controls, and personal protective equipment (respirators) to control risks of exposures to employees. Failing to measure silica exposure levels has been the most cited violation by OSHA under the new silica standards.

RHP’s Silica Exposure Assessment Process & Exposure Control

RHP works with the industry and employers to evaluate and measure worker/workplace exposures of airborne concentrations in the breathing zones and analyze the data in conjunction with accredited laboratories that specializes in industrial hygiene chemistry. The sampling results are compared to OSHA’s Permissible Exposure Limit (PEL) of 50 µg/m3, and the Action Level (AL) of 25 µg/m3, each averaged over an 8-hour day to advice on controls and/or validate compliance.

Once exposures have been evaluated and documented, RHP professionals work with employers to establish and implement a written exposure control plan or to update an existing plan to identify tasks involving silica exposures and methods used to protect workers. Control plan topics may include substitution of safer materials, limiting access to dusty areas, engineering controls, and personal protective equipment.

In the General Industry and Maritime Standards and General Construction Standards exposures above OSHA’s Permissible Exposure Limit (PEL) require controls that will reduce exposures below 50 ug/m3. Controls include actions such as engineering controls – local exhaust ventilation; or, if engineering controls are not feasible, respirators. Where respirators are used as a control to exposures, it is critical to understand respirators and certain PPE are covered by an OSHA regulating written program that entails employee training, annual medical clearances, and respirator fit testing. An effective and compliant respiratory protection program can be expensive and cumbersome to maintain and is one of the least effective means of controlling exposures.

Employers should consider limiting workers’ access to areas where they are at risk of exposure above the permissible exposure limit (PEL) and implementing housekeeping practices to minimize dust generation in areas of concern. Examples of such practices include prohibiting use of compressed air, restricting dry sweeping, and employing the use of high efficiency vacuums or wet cleaning methods. Whenever feasible, water can be effective in reducing dust and consequential employee exposures. Water has been used in industry as an effective method during sweeping and concrete and stone cutting activities.

Under the regulations, employers must offer medical exams, including chest X-rays and lung function tests – every three years for workers exposed at or above the AL (Action Level) for 30 or more days per year. Beginning in June 2020, medical surveillance is required to be offered to any employee who is exposed above the PEL (above 50 µg/m3) for 30 or more days a year.
Important compliance actions include:

⦁ Providing worker training on how to minimize silica exposures.
⦁ Repeating training periodically and at the time of hire for new employees.
⦁ Supervisor participation in training employees and enforcing compliance.
⦁ Keeping records of air sampling, workers’ silica exposure levels, and medical exams.

Conducting a periodic review/audit of your health and safety records, and particularly those related to exposure risks such as silica, by trained and experienced professionals such as those at RHP provide peace of mind and assurance of OSHA criteria compliance.

Benefits of Silica Exposure Assessment & Exposure Control Services

All employers have a moral, ethical, and legal responsibility to provide a safe and healthy workplace with programs and systems in place to protect employees from a vast range of workplace hazards. Through our Silica Exposure Assessment and Exposure Control services, RHP professionals work with companies, industries and employers, private and public, to develop programs that lead to a greater level of employee protection, OSHA compliance, lower administrative and operating costs and a effective and productive workforce and a happier, healthier, and safer workplace. Workplace injuries are costly in manpower, regulatory citations and liability claims.

Silica Consulting Services For You

RHP Risk Management’s Certified Industrial Hygienists (CIH), public health scientists and certified safety professionals are well versed and knowledgeable in navigating clients through the OSHA Silica regulations, in identifying and mitigating worker exposures to crystalline silica, and by recommending and implementing controls that are effective, efficient, and economically feasible.

Contact our industry experts today to learn more about our Silica consulting services.