Glass and Ceramic Manufacturers Need to Get Ready for New Silica Standards
How can glass and ceramic manufacturers be certain that they are ready for the new general industry standard for respirable crystalline silica?
The Occupational Health and Safety Administration (OSHA) will begin enforcing the new general industry standard for respirable crystalline silica on June 23. How can glass and ceramic manufacturers be certain that they are ready, and what should they do if they aren’t?
What is Respirable Crystalline Silica?
Crystalline silica (SiO4) is one of the most common compounds on Earth, making up nearly 12% of its crust. While most people are familiar with its common form, quartz, crystalline silica is a large component of sand, granite and many other types of rock. Silica’s chemical properties and abundance make it highly useful for many industrial applications. It is the main ingredient in glass and is a major component of ceramic tile, cement, brick, and asphalt.
In its solid form as quartz or in grains of sand, silica is chemically inert and is not considered dangerous to human health. However, when silica is cut, ground, drilled, sanded or crushed, tiny breathable particulates of silica are created. These particles, which are at least 100 times smaller than ordinary sand and often invisible to the eye, are known as respirable crystalline silica (RCS). Many processes in the glass and ceramic industry produce these tiny particulates of silica, which can have serious health implications.
Potential Health Impacts
RCS can be breathed deep into the lungs when inhaled. The tiny particles can cause damage to the lungs themselves and cross into the bloodstream, where they can be carried to other body systems.
OSHA estimates that thousands of workers in the U.S. are impacted by RCS-related health problems each year. Some of these health problems can become chronic or even fatal. Occupational exposure to RCS is linked to:
- Lung cancer
- Chronic obstructive pulmonary disease (COPD) and other lung conditions
- Kidney disease
- Autoimmune disorders
- Cardiovascular impairment
Of these conditions, silicosis may be the most common and serious effect of RCS exposure. Silicosis develops when scar tissue forms in the lungs, making it difficult for the lungs to take in oxygen. In severe cases, the condition is highly debilitating or even fatal. It is usually the result of prolonged exposure over several years or decades; in rare cases, it can develop faster at high levels of exposure. Symptoms include shortness of breath with exertion, fatigue, chest pain and, eventually, respiratory failure.
Understanding the New Standard
Health concerns were behind OSHA’s decision to lower the permissible exposure limit (PEL) for RCS for both Construction and General Industry in 2016. While the Construction standards went into effect in September 2017, most companies in the glass and ceramic industry fall under OSHA’s General Industry standard, which will be enforced starting June 23. (Enforcement for the medical surveillance portion of the standard does not begin until June 23, 2020.)
The new standard cuts PELs for RCS in half, to just 50 micrograms per cubic meter of air (mg/m3). The new standard comprises two parts that companies must understand: Action Level and Permissible Exposure Limit.
The Action Level (AL) refers to the airborne level of silica that creates a hazard to workers. If the AL is exceeded, employers must conduct exposure monitoring, initiate a medical surveillance program for employees who are at or above the AL on 30 or more days per year, and provide a respirator to any employee who requests one. The action level for workplace exposure to respirable crystalline silica is 25 micrograms per cubic meter of air (25 µg/m3) calculated as an 8-hr time-weighted average (TWA) exposure.
Permissible Exposure Limit
The Permissible Exposure Limit is a time-weighted average concentration that must not be exceeded during any 8-hr work shift of a 40-hr workweek. OSHA has set a PEL of 50 micrograms of respirable crystalline silica per cubic meter of air (50 µg/m3).
OSHA PELs are set with consideration of the technical and economic feasibility of achieving the standard, as well as the health risks for workers. It is important to understand that meeting the PEL will not necessarily ensure that workers are completely protected from the health impacts of RCS exposure.
The American Conference of Government and Industrial Hygienists (ACGIH) and the National Institute of Occupational Safety and Health (NIOSH) each have set their own recommended limits. These are set based purely on scientific evidence of the human health impacts, without consideration of technical or economic factors.
Unlike OSHA PELs, they do not have the force of law, though OSHA uses the NIOSH recommendation as one source of information when setting exposure standards. However, companies that want to provide maximum protection to their workers may want to consider aiming for the lower ACGIH standard rather than settling for meeting OSHA PELs.
Reducing Silica Exposure
Starting in June, companies in the glass and ceramic industry will be required to assess worker exposure to respirable crystalline silica and have process and engineering controls in place to keep exposures below the new PELs. OSHA requires that engineering and process controls be used as the first line of defense in reducing RCS exposure. The use of personal protective equipment (PPE) should be limited to situations where PELs cannot be met by other means.
The most important step to take in reducing RCS exposure is controlling particulate levels in the air. Silica dust easily becomes airborne and can spread throughout the facility. Effective dust collection and air filtration will remove silica dust from the air and return clean, filtered air to the facility.
Glass and ceramic manufacturers can take several steps to reduce the volume of silica-containing particulates in the facility’s air. Enclosures, partitions or curtains can be placed around dust-producing applications to keep silica dusts contained as much as possible. This will make dust easier to capture and limit the number of employees who are exposed to RCS.
Good housekeeping and hygiene standards should be enforced to reduce the spread of dust through the facility. For example, high-powered vacuum systems with HEPA filtration should be used to clean dust off of floors and surfaces, as sweeping with a broom will kick dust back up into the air.
High-efficiency dust collection equipment can be installed to filter dust out of the air. Make sure that dust collection efforts meet PELs not just for the facility as a whole, but in the breathing zone for workers who are closest to dust-producing processes.
Source capture methods should be used when possible to collect dust near the point where it is created; this will reduce the airflow required for effective capture and minimize energy and equipment costs. Where source capture is not possible, use an ambient air filtration system that will clean air throughout the facility. A hybrid system may sometimes be needed, with both source capture and ambient elements to meet the new PEL.
If it is not technically feasible to keep dust levels within PELs for all workers, companies must provide PPE, such as a powered air purifying respirator (PAPR) system, for employees working in areas with elevated levels of RCS. It is important to keep in mind that this is a last-resort solution; if engineering controls can be used, they must be.
Is Your Plant Ready?
Companies have had nearly two years to prepare for the new OSHA respirable crystalline silica standard. However, many companies may find themselves unsure if they are ready for the enforcement period to begin this summer.
The first step is an evaluation of the facility’s current air quality and RCS exposure levels. Companies should evaluate both concentration levels in the ambient air and personal exposure levels for employees most at risk.
Dust concentration meters measure total particulate levels. During an evaluation, they should be placed at various locations around the facility to develop an exposure map. Collected particulates can be analyzed at a lab to determine the percentage of RCS in the dust sample. Employees working directly in areas with high levels of dust can wear collection filters near the breathing zone to measure their exposure over the course of a shift. Once current exposure levels are known, companies can create an exposure control plan for reducing exposure to RCS.
There is still time to install new engineering controls to reduce RCS exposure levels before enforcement begins, but the clock is ticking. Companies that are not already prepared to meet the new standard should consult with an air quality specialist right away to develop an action plan.
OSHA General Industry and Maritime Standard Requirements for Respirable Crystalline Silica
- Establish and implement a written exposure control plan that identifies tasks that involve exposure and methods used to protect workers.
- Use dust controls to protect workers from exposures above the Permissible Exposure Limit.
- Use housekeeping methods that do not create airborne dust.
- Keep records of exposure measurements, objective data and medical exams.
- Assess exposure levels.
- Limit access to areas where workers may be exposed above the Permissible Exposure Limit.
- Train workers on work operations that result in silica exposure and ways to limit exposure.
- Implement a medical surveillance program.
- Offer medical exams, including chest X-rays and lung function tests, every three years.
- For Employees Working in Areas where PELs Cannot Be Met with Engineering Controls
- Make respirators available to employees when working in areas where they will be exposed above the Action Level.
- Make respirator use mandatory in areas where workers are exposed above the Permissible Exposure Limit.