Regulations for acceptable exposure limits of respirable crystalline silica (RCS) have been in place for decades. However, enforcement of new standards began September 23, 2017. With these new rules, OSHA has lowered the permissible exposure levels (PELs) for RCS to 50 μg/m3, averaged over an 8 hour shift, and now requires the use of engineering controls to limit worker exposure to RCS.
For many firms, exposure control plans already in place are sufficient to meet rule requirements and little to no action is needed. New businesses or those unfamiliar with OSHA standards for respirable crystalline silica can take a few steps to assess whether consultation and action is needed. Below are answers to three commonly asked questions regarding RCS.
Question 1: What Is Respirable Crystalline Silica?
Respirable crystalline silica is the amount of silicon dioxide that can be inhaled without significant health risks: less than 10 microns in aerodynamic diameter. Silicon dioxide is a naturally occurring compound often found in sand, soil, granite, quartz, and other minerals. Construction materials such as sand, concrete, mortar, and stone, contain crystalline silica. It is also present in some manufactured products such as glass, pottery, ceramics, bricks, concrete, and artificial stone.
Inhalation of RCS is a known risk factor for airway diseases such as lung cancer, pulmonary tuberculosis, and silicosis, all of which can be fatal. Businesses working in construction and manufacturing of products containing crystalline silica are already familiar with the acute dangers of working with it.
Workers are most exposed to harmful silica particles while performing several construction and general industry activities, including sawing, grinding, and drilling concrete, abrasive blasting with sand, rock/well drilling, concrete mixing, road construction, transport of gravel, and sweeping of concrete dust, among others.
Question 2: How Do I Know if Permissible Exposure Limits (PELs) Are Exceeded in My Workplace?
First, identify the workplace activities that could potentially expose workers at risk to RCS.
An exposure assessment may be necessary to measure the expected levels of respirable silica that individual workers are likely to be exposed to at or above the action level during construction and/or manufacturing activities. This assessment can take one of two forms:
- Performance Option: 8-hour time weighted average (TWA) exposures are assessed using any combination of air monitoring data or objective data sufficient to accurately characterize employee exposure to respirable crystalline silica
- Scheduled Monitoring Option: the superintendent prescribes a schedule for performing initial and periodic personal monitoring
An option will be prescribed depending on which activities are being performed and the existing PELs in the work environment.
Question 3: What Methods Can Be Used to Limit Exposure?
Cautionary control methods are used to limit respirable crystalline silica exposure during construction and general industry activities. Common methods include engineering controls, which OSHA defines as “methods that are built into the design of a plant, equipment or process to minimize the hazard.”
Some common engineering controls used to reduce exposure include vacuum dust collectors and water spray to control dust while cutting or grinding, and local exhaust ventilation and enclosure. The use of personal protective equipment (PPE) such as gloves, coveralls, eye protection and NIOSH approved respirators could reduce the exposure levels of the worker. Other controls to limit chronic exposure include housekeeping. Workplace best practices can greatly minimize exposure.
If you’d like an experienced environmental consultant to come onsite to assess your RCS exposure based on either the performance or scheduled monitoring option, contact us.
Omega Environmental is a full-service environmental management and hazardous materials consulting firm. Our staff has more than 25 years of project experience in include management positions servicing the public and private sectors relative to construction and development of properties.