Occupational Exposure to Respirable Crystalline Silica in Stone Countertop Fabrication Facilities in Georgia

1243 

Professional Poster 

S Castillo¹

¹Georgia Institute of Technology, Atlanta, GA

Sean Castillo, MPH  
Georgia Institute of Technology

Stone fabrication employees receive potential exposure to respirable crystalline silica (RCS) via cutting, grinding, polishing stone products. Facilities often perform these tasks dry, which exacerbates RCS exposure and leads to overexposures. This presentation will discuss the findings of RCS exposure assessments at stone fabrication facilities, including challenges of compliance with the silica standard. Limitations of current practices that often lead to overexposure and the limitations and variability in sampling procedures will be highlighted. The posters will provide information on how the OSHA Consultation Program helps small businesses in Georgia through exposure assessment and hazard control to ensure worker health.

According to OSHA, nearly 2.3 million people in the United States are exposed to silica (known carcinogen) at work. Without proper controls, exposure to respirable crystalline silica (RCS) can lead to the incurable lung disease silicosis. The Occupational Safety and Health Administration created a new standard for inhalation exposure to respirable crystalline silica that became enforceable for general industry workplaces on June 23, 2018. For small businesses who specialize in natural and engineered stone countertop fabrication in the state of Georgia, compliance with the standard and ensuring sufficient employee protection has been challenging. Within the Georgia Tech OSHA Consultation Program, what level of compliance is the Georgia Tech OSHA Consultation Program observing? What are the reasons for noncompliance and how can facilities decrease exposure with feasible engineering, work practice, and administrative controls? How can the Georgia Tech OSHA Consultation Program conduct industrial hygiene surveys to assess for silica exposure?

By employer request, the Georgia Tech OSHA Consultation Program conducts confidential on-site consultation visits for small businesses. The program has conducted visits to assess compliance with the silica standard. During a consultation visit industrial hygienists assess work practices that may contribute to exposure to respirable crystalline silica and perform personal air monitoring. The industrial hygienist performs silica monitoring with various air monitor pumps (e.g., Gillian 10i, SKC Airchek touch, Casella Apex). Cyclones used for respirable crystalline silica monitoring include BGI cyclones (flow rate of 4.2 lpm) and Dorr Oliver Cyclones (flow rate of 1.7 lpm). Depending on the cyclone used, 2 or 3 piece 37 mm, preweighed 5 micron PVC filters were used for sampling. During cutting and polishing operations Dorr Oliver Cyclones are often used due to the presumed higher exposures of respirable crystalline silica, while BGI cyclones are used in CNC operations due to lower presumed exposures. Personal silica monitoring samples are sent to the Wisconsin Occupational Health Laboratory to be analyzed using X-ray diffraction based on OSHA method ID 142. After results have been received the Georgia Tech industrial hygienists assess the facilities compliance with the silica standard depending on the employees exposure level and issue citations as needed. Businesses are then tasked with providing written documentation that serious hazards have been abated. After initial visits have been conducted follow-up visits may occur if the facility requests assessment of their facility after engineering, work, or administrative controls have been implemented.

Since enforcement of the silica standard has been implemented, the Georgia Tech OSHA Consultation Program has conducted 15 consultation visits to evaluate respirable crystalline silica exposure for employees working in stone countertop fabrication facilities. Most small facilities who perform stone countertop fabrication have employee exposures at or above the OSHA action level. The Georgia Tech OSHA Consultation Program has worked with these facilities to implement suitable engineering, administrative, and work practice controls to reduce employee exposure. The introduction of work practice controls (e.g., water-fed tool systems) have been helpful in reducing exposures, however some facilities still experience exposures above the OSHA action level and PEL (CNC/routing operators, polishers, cutting operations). Many factors (e.g., type of stone used) may alter exposure results. Certain fabricated stones has higher average silica percentage such as quartz and engineered stone (>93%) compared to natural stones such as granite (10-45%). Other factors such as time spent on certain processes can reduce or increase exposure levels.

As employers become more aware about the dangers of silica exposure and illnesses such as silicosis and the OSHA Compliance Directive and National Emphasis Program for RCS is released, an increase in consultation requests to stone countertop fabrication facilities is anticipated. The consultation program will continue to perform industrial hygiene surveys and will have to navigate how to assess silica exposure as sampling techniques and methods for controls are always changing.

IH Profession

Consulting

Sampling and Analysis