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Ventilation System EvaluationWe visually inspected the air-handling unit on a mezzanine inside the production floor andexhaust fans throughout the facility. We also inspected the accessible ductwork for damage.In addition, using thin paper strips, we evaluated pressurization of the production floor withrespect to the adjacent office area.Review of Company Safety and Health RecordsWe reviewed two industrial hygiene reports the company provided. The reports includedrespirable crystalline silica sampling results collected by an industrial hygiene consultant inApril and May 2014. We also reviewed the company’s written respiratory protection program.We reviewed the Occupational Safety and Health Administration (OSHA) Form 300 Logof Work-Related Injuries and Illnesses for the years 2009–2014. As specified by OSHA,work-related injuries and illnesses are categorized into six groups: injuries, skin disorders,respiratory conditions, poisoning, hearing loss, and other [OSHA 2014]. Althoughrecommended by OSHA and NIOSH for silica exposed employees, the company had nomedical surveillance program [OSHA 2015a]. We noted that the program for respiratorclearance involved spirometry, but not the medical testing and follow-up recommended forsurveillance purposes.Review of Spirometry Test ResultsThe company provided spirometry for respirator clearance for its employees. Spirometrytests measure how much (volume) and how fast (flow) a person can move air into and outof your lungs. During our site visit, we requested all spirometry reports for current andformer employees. We received copies of spirometry results for testing completed onOctober 6–7, 2014. According to the spirometry provider, this was the first time that theyconducted testing on employees at this facility.Confidential Medical InterviewsWe invited all 58 employees working in the production and office areas on the dates of ourvisit to participate in confidential medical interviews. These interviews were conducted inEnglish or Spanish with assistance from public health interpreters. We discussed workplaceexposure and work history, medical history, use of personal protective equipment (PPE) atwork, and work practices.ResultsAir Sampling for Respirable Crystalline SilicaFull-shift Personal Air Sample ResultsEmployees used wet methods throughout the facility. Stone cutting and polishing hand toolsor saws were equipped with a water spray to help control dust generated by the tool (FigureHealth Hazard Evaluation Report 2014-0215-3250Page 3

1). The water lines connected to the hand tools were equipped with a control knob thatallowed the user to adjust the amount of water flowing to the tool. Some employees usedhigher water flow rates than others. We saw no dry cutting in the facility.Figure 1. Photo of a pneumatic wet grinder equipped with a diamond cup wheel and a water sprayused in the polishing area. Photo by NIOSH.Employees and management reported that they typically work with both natural andengineered stone over the course of a normal day. Throughout the work shifts we observed,each employee worked with engineered and natural stones. The time spent working witheach type of stone varied on the basis of customer orders and production demands. For thefull-shift air samples, we were not able to track and document the time spent working witheach type of stone. However, for the short-term, task-based samples, we documented whetheremployees worked with granite, engineered quartz, or both during the sample period.Table A1 in Appendix A shows detailed full-shift time-weighted average (TWA) personal airsampling results. The bolded values in these tables show where silica exposures were at orabove an occupational exposure limit (OEL). The OSHA permissible exposure limit (PEL)varies based on the percent quartz in each respirable dust sample, as discussed in AppendixB. The NIOSH and American Conference of Governmental Industrial Hygienists (ACGIH )OELs for respirable crystalline silica do not vary on the basis of the percent quartz. Whenemployees worked longer than an 8-hour work shift, we adjusted the ACGIH threshold limitvalue (TLV ) according to procedures recommended by Brief and Scala [1975]. The NIOSHlimit is not adjusted for extended work shifts and represents exposures up to a 10-hourworkday during a 40-hour workweek.Page 4Health Hazard Evaluation Report 2014-0215-3250

Over both days of sampling, the percentage of quartz in the respirable dust of the full-shift airsamples ranged from nondetectable (ND) to 52% (Table A1). We collected two bulk dust samplesfrom the areas near the work benches in the manual polishing area. One contained 48% quartz andone 70%. No cristobalite or tridymite were detected in any of the bulk or air samples.Table 1. Number of respirable dust and crystalline silica samples at or above any OEL overtwo days of samplingJob titleNumber ofsamples collectedNumber of samplesabove any OELOffice area employee20Material handler31Quality control/finishing10Vanity20CNC operator40Laminator21Bridge saw30Water jet cutter30Comandulli Omega operator30Comandulli Synthesis operator20Polisher - resin bonded disc50Grinder - diamond cup wheel44Computer-aided design department10Maintenance10**The air sample for the maintenance employee contained excessive visible debris on theair sampling filter. The employee had limited exposure to airborne silica during his work activities.The sampling result is not likely representative of the employee’s actual exposure.Table 1 presents summary results showing the number of crystalline silica or respirabledust samples at or above any OEL, over both days of sampling. Overall, the full-shift TWArespirable dust exposures ranged from ND to 380 micrograms per cubic meter (µg/m3),while the respirable crystalline silica exposures ranged from ND to 140 µg/m3. For bothsampling days, the full-shift exposures of the employees using the pneumatic wet grinderswith diamond cup wheels during the final polishing stage of production were all at or abovethe OSHA PEL, the NIOSH recommended exposure limit (REL), and the ACGIH TLVfor crystalline silica. In contrast, none of the other production employees we sampled hadexposures at or above the OSHA PEL for respirable dust containing crystalline silica. Thisincluded the pneumatic polishers with a resin bonded disc.Health Hazard Evaluation Report 2014-0215-3250Page 5

The polishers and grinders used similar-looking hand tools, with the major differences beingthe type of disc that was used and the speed at which they were run. The polishers used resinbonded discs that ran at about 4,500 RPM, while the grinders used diamond cup wheels thatran at about 7,000 RPM. Figure 2 depicts a worker using one of the hand polishing tools.Figure 2. Employee using a hand polishing tool outfitted with a water spray. Photo by NIOSH.Aside from the employee using the hand grinders equipped with diamond cup wheels, noother employees had an exposure to respirable dust containing crystalline silica above theOSHA PEL or to crystalline silica above the NIOSH REL. However, other employees on theproduction floor had exposures to crystalline silica above the ACGIH TLV. On the first dayof sampling, the laminator’s exposure was above the ACGIH limit of 25 µg/m3. Laminators’exposures to silica likely occur during their use of saws to cut small strips of stone orduring their use of hand-held grinding and polishing tools (Figure 3). On the second day ofsampling, the material handler was exposed to a crystalline silica concentration above theadjusted ACGIH limit of 13 µg/m3 for a 12-hour shift. During the second day of sampling,a CNC operator, a Comandulli Omega operator, and a laminator all had exposures close to,but slightly below, the adjusted ACGIH TLVs. None of the other employees monitored wereexposed above any of the OELs for silica. Employees working in the adjacent office areasdid not have detectable exposure to respirable dust containing crystalline silica or respirablecrystalline silica.Page 6Health Hazard Evaluation Report 2014-0215-3250

Figure 3. Photo of a lamination employee making a cut with a miter saw. Photo by NIOSH.Task-based Air Sampling ResultsTable A2 in Appendix A reports the TWA respirable dust concentrations and the TWArespirable crystalline silica concentrations for short-term, task-based breathing zone airsamples. There are no short-term OELs for silica. These samples provided information aboutthe employee’s exposure to crystalline silica while performing specific tasks.Overall, respirable dust exposures during the short-term polishing and grinding tasks ranged fromND to 430 µg/m3 for the polishers, and from 200 to 550 µg/m3 for the two grinders. Respirablecrystalline silica exposures during the short-term polishing and grinding tasks ranged from ND to140 µg/m3 for the polishers, and from 50 to 140 µg/m3 for the two grinders.Ventilation System EvaluationNo mechanical heating or cooling was provided to the main production floor by a heating,ventilation, and air-conditioning (HVAC) system. However, general exhaust ventilation ofthe production floor was provided by large exhaust fans in the roof of the building and largebay doors on the east end of the building. These doors were open at the time of our visit. Theemployer stated that the doors were typically open, except during the winter. None of thework processes used local exhaust ventilation.Two rooftop-mounted Trane air-handling units provided ducted supply air to the officespaces adjacent to the production floor. A Payne air-handling unit on a mezzanine inside theproduction floor and outside the conference room also served the office space. We observedstanding water and extensive rust and biological growth in the condensate drain pan for thePayne air-handling unit (Figure 4). We also observed that the unit was missing its air filterHealth Hazard Evaluation Report 2014-0215-3250Page 7

and that some of the flexible duct attached to the unit was torn (Figure 5). This unit was inthe production area, so openings in the flexible duct could allow crystalline silica or otherdusts from the production area to enter the office space. Employer representatives stated thatan HVAC contractor serviced these units, and that they were unsure how often the filterswere changed.Pressurization checks between the production floor and the adjoining office space indicatedthat the production floor was negatively pressurized with respect to the adjacent office area.This will help limit the amount of airborne crystalline silica or other dust entering the officespace when employees open the door to the production floor.Figure 4. Discolored standing water in the drain pan of the air-handling unit on the mezzanine. Photoby NIOSH.Figure 5. Torn flexible duct attached to the air-handling unit on the mezzanine. Photo by NIOSH.Page 8Health Hazard Evaluation Report 2014-0215-3250

Workplace Observations and Safety HazardsPersonal Protective Equipment UseEmployees in production areas were required to use respiratory protection, hearingprotection, eye protection, rubber safety shoes, nylon knitted work gloves with latex dippedpalms and fingers, and vinyl aprons. The employer provided uniforms to the employees at thebeginning of each day. A contractor laundered the uniforms offsite. We observed that not allemployees properly wore their safety glasses while on the production floor. We observed oneemployee wearing safety glasses on top of his head while using a hand polishing tool. Notall employees wore gloves while on the production floor, and some employees had cut offthe tips of their gloves. We also observed an employee wearing his insert-type foam hearingprotection sideways in his ear. Additionally, it appeared that some employees did not inserttheir hearing protection deeply enough into their ear canal.We observed that all employees wore respirators when entering the production floor asrequired by the company. Production employees wore elastomeric, half-face air-purifyingrespirators (3M model 7502). Most production employees used P100 particulate filtercartridges (3M model 7093) with their respirator; however, laminators used combinationP100 and organic vapor cartridges (3M model 60921). The respirator program administratorreported that employees changed P100 cartridges once per week and changed combinationcartridges at least once per month, but could change them more often if requested. Anemployee reported during informal discussions that he usually changed cartridges once eachweek. Employees who were not primarily working on the production floor, such as managersor office staff, donned N95 filtering facepiece respirators (3M model 8200 or ULine modelS-9632) prior to entering the production floor. In most instances, respirators were wornproperly. However, we observed the following instances of improper respirator use: Some employees wore the straps of N95 filtering facepiece respirators incorrectly, suchas wearing both straps around the base of the neck, using only one of the two straps, orcutting off one of the straps. Respirators only fit tightly and seal properly if both strapsare used correctly. Some employees or managers had facial hair that could interfere with the seal of therespirator to the face. We observed that employees or managers sometimes pulled the respirator away fromtheir face when speaking with other employees. This practice allows air contaminantsto be breathed in.Safety HazardsThe handle on the maintenance office door was broken, and the door would not close. Thisoffice was connected to the production floor, and the open door could allow airborne silica toenter the maintenance office (Figure 6). The maintenance supervisor used the office and didnot wear a respirator when inside.Health Hazard Evaluation Report 2014-0215-3250Page 9

Figure 6. View of broken door from inside of the maintenance room, looking out to the productionfloor. Photo by NIOSH.We observed that the pneumatic stone slab lifter attached to a half-ton overhead craneremained in a suspended position about 6 to 8 feet above the floor during times it was not inuse. Employees sometimes walked under the suspended slab lifting device (Figure 7).Figure 7. Slab lifter attached to overhead crane. Photo by NIOSH.Page 10Health Hazard Evaluation Report 2014-0215-3250

We observed an employee standing on the side of a forklift, which is an unsafe work practice,while the forklift operator lifted and removed large stone slabs from a semi-trailer. Theemployee was helping instruct the operator on positioning the forks and backing the slabs outof the trailer without damaging other slabs in the trailer.We noted several electrical safety hazards during our site visit, specifically: Electrical cords were lying in water (Figure 8). Electrical cords had damaged or torn insulation jackets. Some had been repaired usingelectrical tape (Figure 9), and others had exposed inner wires (Figure 10). Three long lengths of extension cords were daisy-chained (i.e., connected in series)from the production building to the outside stone slab storage area behind the building.We also observed extension cords daisy-chained to power strips. An electrical junction box attached to a Comandulli machine was severely damagedfrom oxidation and rust. The electrical power supply fittings were dangling loose fromthe junction box, exposing internal electrical wiring junction box connection points(Figure 11). A forklift operator drove over an extension cord that had been stretched acrossthe inclined loading dock in the back of the building. The cord was plugged intoan electrical outlet in the building and was connected to a series of daisy-chainedextension cords that were stretched across a field to a reciprocating saw being used tocut wooden support frames in the back of a semi-trailer. The expanded metal housing on the end of a Comandulli machine motor was corrodedand partially missing.Figure 8. Electrical cords in water. Photo by NIOSH.Health Hazard Evaluation Report 2014-0215-3250Page 11

Figure 9. Electrical cords with damaged or torn insulation jackets. Photo by NIOSH.Figure 10. Extension cord with damaged insulation jacket near the plug. Photo by NIOSH.Figure 11. Severely damaged electrical junction box at Comandulli machine. Photo by NIOSH.Page 12Health Hazard Evaluation Report 2014-0215-3250

Review of Company Safety and Health RecordsReview of Industrial Hygiene ReportsThe company provided us with two industrial hygiene reports. These reports detailedthe results of personal air sampling for respirable crystalline silica. In April 2014, aninsurance company representative did personal air sampling on four employees. None of theemployees’ 8-hour TWA exposures were greater than 50% of the OSHA PEL, and no sampleswere above the NIOSH REL of 50 µg/m3. However, three of the four personal sampleswere above the ACGIH TLV of 25 µg/m3. The employees overexposed to the TLV includedone working at the bridge saw, one using a Comandulli machine, and one doing countertopmanual fabrication. The type of tool used by the employee performing the manual fabricationtasks was not reported. The employee who was not overexposed was reported to be doingmaintenance tasks and working in the “filteration” [sic] room. While we did not observe anyoverexposures in our sampling for the bridge saw operators, one of the Comandulli operatorshad crystalline silica exposures just below the TLV. The results for the employee performingmanual fabrication are not directly comparable to our results, as we do not know what type oftool the employee was using.In May 2014,

HHE Report No. 2014-0215-3250. March 2016 Leonard M. Zwack, ScD. Kerton R. Victory, PhD, MSc . U.S. Department of Health and Human Services Centers for Disease Control and Prevention National Institute for Occupational Safety and Health. Page 2 ea aa vaai e 201402153250. Contents. Highlights . We found several electrical safety hazards .