Industrial Hygiene Report: Results of Silica and Dust Air Monitoring

Transcription

1 September 28, 2017 Industrial Hygiene Report: Results of Silica and Dust Air Monitoring CHP-Truckee Area Office Replacement Facility Pioneer Trail Road Truckee, CA Prepared for: Mr. Kevin MacDonald Townsend & Schmidt Masonry 8788 Elder Creek Road Sacramento, CA Prepared By: Ms. Sylvia Fontes, MS, CIH 7625 Sunrise Boulevard, Suite 104 Citrus Heights, CA FACS Project #PJ33196

2 Contents Executive Summary... 1 Introduction... 1 Scope of Work... 2 Site and Process Characterization... 2 Findings and Results... 3 Conclusions... 3 Requirements and Recommendations... 3 Limitations... 4 APPENDIX A: Photographs APPENDIX B: FACS Data Collection Methods APPENDIX C: Sampling Results Summary Laboratory Report

3 1 of 5 Executive Summary Personal air monitoring for respirable dust and crystalline silica was performed on Townsend & Schmidt Masonry employees at the California Highway Patrol Truckee Area Office Replacement Facility site while performing various masonry work. Monitoring was performed on September 14, Personal air sample results indicated worker exposures to respirable dust and crystalline silica did exceed regulatory exposure limits (California Occupational Safety and Health Administration [Cal/OSHA] Permissible Exposure Levels [PELs]). A more complete discussion of findings, conclusions and recommendations is provided below. Introduction, Inc. (FACS) was retained by Townsend & Schmidt Masonry to perform personal air monitoring for respirable dust and crystalline silica on masonry employees at the California Highway Patrol (CHP) Truckee Area Office Replacement Facility site located at Pioneer Trail Road in Truckee, California. Air sampling was performed by Mr. Salvador Mendoza, an Industrial Hygiene Technician of FACS on September 14, The purpose of the investigation was to assess employee exposure to respirable dust and crystalline silica while conducting various masonry tasks. This report contains the findings of the industrial hygiene (IH) evaluation. Townsend & Schmidt Masonry is a masonry company specializing in brick, stone, block and thin brick veneer construction. The assessment was performed at the CHP-Truckee Area Office Replacement Facility construction site. The assessment was performed during installation and grouting of brick fence along the southern property boundary. FACS evaluated the following tasks involved in the process: mixing of mortar, saw cutting of concrete blocks, and general masonry tasks which included grouting of thin brick veneer joints and cinder block laying. All previously noted tasks were performed outdoors. On the day of sampling, employees work shifts were as follows: Mason 1 (M1) 7:00 3:30 Mason 2 (M2) 7:00 3:30 Mason 3 (M3) 7:00 3:30 Mason 4 (M4) 7:00 3:30 The purpose of this investigation was to 1) characterize agent concentrations by conducting sampling for silica; 2) provide information for consideration in assessing risk to workers; and 3) provide recommendations for further assessment or controls, as necessary. This report contains findings and recommendations from the assessment, as well as a description of methods used and activities conducted during the exposure assessment process. The assessment was conducted by Mr. Mendoza, Industrial Hygiene Technician of FACS on September 14, The findings contained in this report are based solely on the results of sample analysis and on-site observations from the assessment date listed. Additional sites or agents not discussed in this report are not represented. Representative photographs are presented in Appendix A. Data collection methodologies are described in Appendix B. Sample results (summary table, laboratory reports, and chain of custody forms) are presented in Appendix C.

4 2 of 5 Scope of Work In the course of this project, FACS conducted the following scope of work: Development of a site characterization (see section above). Evaluation of work tasks, including review of engineering controls, administrative controls, and personal protective equipment on site. Collection of personal air samples for respirable dust and crystalline silica. Personal air samples for respirable dust and crystalline silica were collected from four masons during a work shift which involved mixing mortar, saw cutting, coring, and drilling of concrete blocks and/or grouting of block fence wall located along the southern property boundary at the CHP-Truckee Area Office Replacement Facility construction site in Truckee, CA. All four employees were monitored for the duration of their shifts while performing various masonry tasks. Site and Process Characterization The following information was gathered onsite and during conversations with the onsite staff. Grossing Observations Mason 1 (M1) was monitored during foreman activities of the crew. The onsite foreman is responsible for onsite production. Foreman tasks include; supervising workers, site safety, and overall daily operations. Personal protective equipment used by M1 included work boots, hard hat, high visibility shirt, safety vest and safety glasses. Mason 2 (M2) conducted saw cutting activities for the full duration of the work shift. Saw cutting activities were performed using a 5 horsepower (hp) MK Diamond Products Concrete Masonry Saw with a 20 blade, equipped with an iq PowerTools iq2000 Dust Collector. M2 worked on approximately 60 concrete blocks, each block consisting of approximately four (4) cuts each. M2 conducted coring by using a handheld Makita GA702 hammer drill which is connected to a Unitec 6.6 gallon vacuum (Model No. CS 1225) equipped with HEPA filters. M2 conducted drilling using a handheld HILT TB55 (Model No ) hammer drill which is connected to a BOSCH 6.0 gallon vacuum (Model No. VAC090A) equipped with a HEPA filter. Personal protective equipment used by M2 included work boots, hard hat, safety vest, earplugs, MOLDEX 2200NN95 particulate respirator, and prescription glasses. Visible airborne dust was identified during the saw cutting work being performed on concrete blocks. Dust created by saw cutting appeared to be captured at the source and drawn into the dust collector filters. Periodically (approximately every 30 minutes), the saw was powered off by M2 who then manually cleaned the filters by shaking the filter bank with the doors closed. This shaking operation deposited dust from the filters to the collection tray located beneath the filter bank. Airborne dust was not observed during the coring or drilling activities. Mason 3 (M3) conducted typical hod carrier (i.e., a laborer employed in carrying supplies to bricklayers, stonemasons, cement finishers, or plasterers at a job site). M3 was observed transporting mortar using hand tools and bricks to the work areas. Mortar was transported using; spatulas, shovels, and/or via 20 gallon hopper using a Gridall GS-42PI forklift. Individual bricks were transported by hand while pallets of bricks were transported using the Gridall forklift. M3 would occasionally conduct brick cutting activities consistent with M2 tasks described above. No airborne dust generation was observed during grouting and/or brick laying activities. Mason 4 (M4) performed mortar mixing activities, as well as general masonry activities, including grouting and brick laying. Approximately 70 bags of AMERIMIX preblended water repellent Mortar (80 pound bags) were used during mortar mixing. Mortar mixing was performed at a mixer, utilizing water for dust control. Visible airborne dust was noticeable during the mortar mixing operation. In addition, water used for dust control did not completely eliminate airborne visible dust. Personal protective equipment used by M4 on the day of FACS assessment included work boots, hard hat, high visibility shirt, safety

5 3 of 5 glasses, MOLDEX 2200NN95 particulate respirator, earplugs, and rubber gloves, while mixing mortar. M4 was observed wearing a hard hat, work boots, high visibility shirt and safety glasses during general masonry activities. See Appendix A for photographs of tasks noted above. Collection methods are provided in Appendix B. Findings and Results Personal air samples for respirable dust and crystalline silica were collected from four masonry workers during a typical work shift which included mortar mixing, cutting, and general masonry work as noted above. Results of collected air samples are provided in Appendix C. Results of personal air samples collected were compared to applicable Occupational Exposure Limits (OELs). These include the regulatory Federal and California Division of Occupational Safety and Health (Cal/OSHA) Permissible Exposure Limits (PELs). General Dust: dust samples were initially analyzed gravimetrically for general dust by NIOSH Method The PELs for Particulates Not Otherwise Regulated are only applicable if crystalline silica is not detected in the samples. Based on the review of safety data sheets provided by the client, crystalline silica is an ingredient in the materials worked on during the day of the assessment, and therefore the crystalline silica standards would apply to all samples collected; even those found below the laboratory s limit of detection. Crystalline Silica: Following the gravimetric analysis, the air samples were further analyzed for crystalline silica by NIOSH Method The Cal/OSHA standard for crystalline silica (Title 8 CCR 5155) regulates the maximum permitted 8-hour time-weighted-average concentration of airborne respirable quartz, cristobalite, and tridymite. When exposures are found or are expected to exceed allowable levels, additional measures, to control such harmful exposures (e.g. respiratory protection) shall be instituted. Occupational exposures are generally represented as a time weighted average (TWA), which is the average exposure concentration across the time period evaluated. Full-shift occupational exposure limits (OELs) are typically given as an 8-hour TWA, which represents the maximum average concentration a worker should be exposed to over an 8-hour work day. The following 8-hour TWAs were calculated: Calculated 8hr TWA [same exposure]. The calculated TWA exposure over the 8-hour work day assuming no exposure to the agent during the non-sampled portions of the day. Appendix C contains the data tables with the calculated TWAs. Conclusions Based on this assessment, the following conclusions were reached: 1. Calculated 8hr TWA results of personal air samples collected for crystalline silica indicate that employee exposures are below regulatory exposure limits (Cal/OSHA PELs). 2. The calculated 8hr TWA exceeded the Cal/OSHA Action Level. Requirements and Recommendations Based on this assessment, the following recommendations are provided: 1. Continue the use of exposure controls already in place during all dust generating work known or suspected to contain crystalline silica. Such controls include water suppression and the use of a dust collector on the saw.

6 4 of 5 2. Considering continuing the use of respiratory protection (e.g. N95 dust masks). 3. Conduct additional exposure assessments within 6 months for tasks not yet assessed. 4. Consider additional dust control methods during the mortar mixing operation to reduce visible dust. Limitations This investigation is limited to the conditions and practices observed and information made available to FACS. The methods, conclusions and recommendations provided are based on FACS judgment, expertise and the standard of practice for professional service. They are subject to the limitations and variability inherent in the methodology employed. As with all environmental investigations, this investigation is limited to the defined scope and does not purport to set forth all hazards, nor indicate that other hazards do not exist. Please do not hesitate to contact our offices at with any questions or concerns. Thank you for the opportunity to assist Townsend & Schmidt Masonry in promoting a more healthful environment. Respectfully, FORENSIC ANALYTICAL Reviewed by: FORENSIC ANALYTICAL Salvador Mendoza Senior Project Manager Sylvia Fontes, MS, CIH Director, Sacramento

7 Appendix A Appendix A Photographs Photo #1: View from the approximate center of the site and looking northeast across a completed section of block fencing. Photo #2: View from the northern portion of the site looking southwest across an unfinished fence section, along the southern property boundary. Photo #3: View depicting M1 and the section of fence being constructed. Photo #4: M2 saw cutting

8 Appendix A Photo #5: Filter bank inside of a dust collection system for the saw cutting. Dust drawer is located beneath the filter bank. Photo #6: Concrete blocks used for saw cutting, coring, and drilling. Photo #7: M3 using a forklift to transport materials (i.e., mortar and blocks). Photo #8: M4 mixing mortar.

9 Appendix A Photo 9: M4 mixing mortar and utilizing water for dust suppression. Photo #10: AMERIMIX preblended water repellent Mortar (80 pound bags) were used during mortar mixing Photo #11: View depicting earplugs used at the site. Photo #12: View depicting the N95 respirators used at the site.

10 Appendix B Appendix B FACS Data Collection Methods Dust and Crystalline Silica. Samples were collected in accordance with NIOSH Method 0600, using a low-volume air sampling pump affixed to a SKC aluminum cyclone operating at a flow rate of 2.5 liters per minute (LPM) on a 37 mm 3-piece cassettes with 5 micron closed faced pre-weighed PVC filter. Flow rates were calibrated pre and post sampling, in line using a Dry-Cal calibrator. Samples were labeled using a unique identification number and shipped under Chain of Custody to an AIHA accredited analytical laboratory (SGS Galson in East Syracuse, New York). Samples and blanks were analyzed in a two step process. Initially, the particulate concentrations are measured by the laboratory using gravimetric analysis (NIOSH 0600). In the second process, the amount of crystalline silica in each sample is measured by the laboratory using X-ray diffraction (XRD) in accordance with NIOSH Method Crystalline silica normally has three silica polymorphs: quartz, cristobalite, and tridymite. Results are expressed in milligrams per cubic meter (mg/m³) for Dust and micrograms per cubic meter (ug/m 3 ) for Crystalline Silica.

11 Appendix C Appendix C Sampling Results Summary and Laboratory Report Sample ID Z Z Z Z Employee Mr. Mike Griffith (M1) Mr. Brad Norris (M2) Mr. Alex Morum (M3) Mr. Nick Bower (M4) Table 1 Sampling Results Summary for September 14, 2017 Silica Dust Exposure Assessment, Townsend & Schmidt Masonry Work Task Sample Duration (min.) Dust (mg/m 3 ) TWA 1 Dust (mg/m 3 ) Foreman Laborer Brick cutting, coring, and drilling Hod Carrier - General masonry Hod Carrier Mortar Mixer Cal/OSHA Permissible Exposure Limit (PEL) - 8 hour TWA 5 5 Federal OSHA PEL ( fraction) 8 hour TWA 5 5 Notes: 1 Exposure assuming there was no exposure to the agent during the non-sampled portions of the day. Results are given in mg/m 3 (milligrams per cubic meter of air). The symbol < means less than and the value following indicates the laboratory reporting limit for the analytical method and sample volume. NA not applicable PEL permissible exposure limit mg/m 3 milligrams per cubic meter of air TWA time-weighted average PELs for Particulates Not Otherwise Regulated for information only. Because the dust contained crystalline silica, per the SDS, the PELs for crystalline silica apply.

12 Appendix C Sample ID Employee Work Task Sample duration (min) Table 2 Sampling Results Summary for September 14, 2017 Silica Dust Exposure Assessment, Townsend & Schmidt Masonry Quartz Cristobalite Result (µg/m 3 ) Tridymite Crystalline Silica (RCS) Quartz Cristobalite TWA 1 (µg/m 3 ) Tridymite Crystalline Silica (RCS) Z Z Z Z Mr. Mike Griffith Mr. Brad Norris Mr. Alex Morum Mr. Nick Bower Foreman 480 <4.2 <4.2 <17 <4.2 <4.2 <4.2 <17 <4.2 Laborer Brick cutting, coring, and drilling Hod Carrier - General masonry Hod Carrier Mortar Mixer <4.1 < <4.1 < <5.9 < <5.9 < <6.7 < <6.7 <17 24 Cal/OSHA Permissible Exposure Limit (PEL) - 8 hour TWA Cal/OSHA Action Level Federal OSHA 10,000 NA NA NA Notes: 1 Exposure assuming there was no exposure to the agent during the non-sampled portions of the day. Results are given in µg/m 3 (micrograms per cubic meter of air). The symbol < means less than and the value following indicates the laboratory reporting limit for the analytical method and sample volume. PEL permissible exposure limit µg/m 3 micrograms per cubic meter of air TWA time-weighted average

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