1
|
Ervik TK, Leite M, Weinbruch S, Nordby KC, Ellingsen DG, Ulvestad B, Dahl K, Berlinger B, Skaugset NP. Characterization of particle exposure during tunnel excavation by tunnel boring machines. Ann Work Expo Health 2024; 68:713-724. [PMID: 38816184 PMCID: PMC11306322 DOI: 10.1093/annweh/wxae041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 05/02/2024] [Indexed: 06/01/2024] Open
Abstract
Tunnel boring machines (TBMs) are used to excavate tunnels in a manner where the rock is constantly penetrated with rotating cutter heads. Fine particles of the rock minerals are thereby generated. Workers on and in the vicinity of the TBM are exposed to particulate matter (PM) consisting of bedrock minerals including α-quartz. Exposure to respirable α-quartz remains a concern because of the respiratory diseases associated with this exposure. The particle size distribution of PM and α-quartz is of special importance because of its influence on adverse health effects, monitoring and control strategies as well as accurate quantification of α-quartz concentrations. The major aim of our study was therefore to investigate the particle size distribution of airborne PM and α-quartz generated during tunnel excavation using TBMs in an area dominated by gneiss, a metamorphic type of rock. Sioutas cascade impactors were used to collect personal samples on 3 separate days. The impactor fractionates the dust in 5 size fractions, from 10 µm down to below 0.25 µm. The filters were weighted, and the α-quartz concentrations were quantified using X-ray diffraction (XRD) analysis and the NIOSH 7500 method on the 5 size fractions. Other minerals were determined using Rietveld refinement XRD analysis. The size and elemental composition of individual particles were investigated by scanning electron microscopy. The majority of PM mass was collected on the first 3 stages (aerodynamic diameter = 10 to 0.5 µm) of the Sioutas cascade impactor. No observable differences were found for the size distribution of the collected PM and α-quartz for the 3 sampling days nor the various work tasks. However, the α-quartz proportion varied for the 3 sampling days demonstrating a dependence on geology. The collected α-quartz consisted of more particles with sizes below 1 µm than the calibration material, which most likely affected the accuracy of the measured respirable α-quartz concentrations. This potential systematic error is important to keep in mind when analyzing α-quartz from occupational samples. Knowledge of the particle size distribution is also important for control measures, which should target particle sizes that efficiently capture the respirable α-quartz concentration.
Collapse
Affiliation(s)
- Torunn K Ervik
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Mimmi Leite
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Stephan Weinbruch
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
- Technical University of Darmstadt, Institute of Applied Geosciences, Schnittspahnstrasse 9, D-64287, Darmstadt, Germany
| | - Karl-Christian Nordby
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Dag G Ellingsen
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Bente Ulvestad
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Kari Dahl
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Balazs Berlinger
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| | - Nils Petter Skaugset
- National Institute of Occupational Health, P.O. Box 5330, Majorstuen, 0304 Oslo, Norway
| |
Collapse
|
2
|
Thompson D, Qi C. Characterization of the Emissions and Crystalline Silica Content of Airborne Dust Generated from Grinding Natural and Engineered Stones. Ann Work Expo Health 2023; 67:266-280. [PMID: 36219621 PMCID: PMC9928769 DOI: 10.1093/annweh/wxac070] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/31/2022] [Accepted: 09/21/2022] [Indexed: 11/12/2022] Open
Abstract
In this study, we systematically characterized the airborne dust generated from grinding engineered and natural stone products using a laboratory testing system designed and operated to collect representative respirable dust samples. Four stone samples tested included two engineered stones consisting of crystalline silica in a polyester resin matrix (formulations differed with Stones A having up to 90wt% crystalline silica and Stone B up to 50wt% crystalline silica), an engineered stone consisting of recycled glass in a cement matrix (Stone C), and a granite. Aerosol samples were collected by respirable dust samplers, total dust samplers, and a Micro-Orifice Uniform Deposit Impactor. Aerosol samples were analyzed by gravimetric analysis and x-ray diffraction to determine dust generation rates, crystalline silica generation rates, and crystalline silica content. Additionally, bulk dust settled on the floor of the testing system was analyzed for crystalline silica content. Real-time particle size distributions were measured using an Aerodynamic Particle Sizer. All stone types generated similar trimodal lognormal number-weighted particle size distributions during grinding with the most prominent mode at an aerodynamic diameter of about 2.0-2.3 μm, suggesting dust formation from grinding different stones is similar. Bulk dust from Stone C contained no crystalline silica. Bulk dust from Stone A, Stone B, and granite contained 60, 23, and 30wt% crystalline silica, respectively. In Stones A and B, the cristobalite form of crystalline silica was more plentiful than the quartz form. Only the quartz form was detected in granite. The bulk dust, respirable dust, and total dust for each stone had comparable amounts of crystalline silica, suggesting that crystalline silica content in the bulk dust could be representative of that in respirable dust generated during grinding. Granite generated more dust per unit volume of material removed than the engineered stones, which all had similar normalized dust generation rates. Stone A had the highest normalized generation rates of crystalline silica, followed by granite, Stone B, and Stone C (no crystalline silica), which likely leads to the same trend of respirable crystalline silica (RCS) exposure when working with these different stones. Manufacturing and adoption of engineered stone products with formulations such as Stone B or Stone C could potentially lower or eliminate RCS exposure risks. Combining all the effects of dust generation rate, size-dependent silica content, and respirable fraction, the highest normalized generation rate of RCS consistently occurs at 3.2-5.6 µm for all the stones containing crystalline silica. Therefore, removing particles in this size range near the generation sources should be prioritized when developing engineering control measures.
Collapse
Affiliation(s)
- Drew Thompson
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Field Studies and Engineering, Cincinnati, OH 45226, USA
| | - Chaolong Qi
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Field Studies and Engineering, Cincinnati, OH 45226, USA
| |
Collapse
|
3
|
Qi C, Thompson D, Feng HA. Caution on Using Tetrahydrofuran for Processing Crystalline Silica Samples From Engineered Stone for XRD Analysis. Ann Work Expo Health 2022; 66:1210-1214. [PMID: 36066421 PMCID: PMC9669205 DOI: 10.1093/annweh/wxac063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/07/2022] [Accepted: 08/12/2022] [Indexed: 12/14/2022] Open
Abstract
We conducted laboratory experiments to investigate a suspected effect of tetrahydrofuran (THF) on quantifying crystalline silica in samples collected from working with engineered stone when THF is used to process samples prior to the X-ray diffraction (XRD) analysis. Two groups of samples from grinding either engineered stone or granite were simultaneously taken from a laboratory testing system, with one group of samples using THF for processing and another group using muffle furnace for ashing. For each stone type, we also tested four levels of respirable dust loading on the samples by varying the grinding time from 1 to 8 min. Statistical analysis of the experimental results on crystalline silica contents of the two groups of samples showed that the difference between the two methods was not significant (P ≥ 0.05) for the granite at all four levels of respirable dust loading and for the engineered stone at the two levels of respirable dust loading greater than 0.5 mg. However, the crystalline silica content from using THF processing was significantly lower (P = 0.001) than that from using muffle furnace ashing for engineered stone when the respirable dust loading levels were less than 0.5 mg. For the engineered stone dust samples with grinding times of 1 and 2 min, the average respirable dust loading was about 0.19 and 0.34 mg, respectively; while the crystalline silica content from using THF processing was 30.9 and 21.5% lower than that from using muffle furnace ashing, respectively. Since most full-shift samples from field assessments in this industry are expected to have respirable dust loading less than 0.5 mg, muffle furnace or radio frequency plasma ashing should be specified as the preferred sample processing method instead of the THF processing method for quantification of crystalline silica when engineered stone is expected to present to avoid artificially reduced silica content values, which are likely caused by the reactions between THF and the resins in engineered stone.
Collapse
Affiliation(s)
- Chaolong Qi
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Field Studies and Engineering, 1090 Tusculum Ave, MS: R5, Cincinnati, OH, 45226, USA
| | - Drew Thompson
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Field Studies and Engineering, 1090 Tusculum Ave, MS: R5, Cincinnati, OH, 45226, USA
| | - H. Amy Feng
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Division of Field Studies and Engineering, 1090 Tusculum Ave, MS: R5, Cincinnati, OH, 45226, USA
| |
Collapse
|
4
|
Wang C, Qi C. Revealing the structural and chemical properties of copper-based nanoparticles released from copper treated wood. RSC Adv 2022; 12:11391-11401. [PMID: 35425055 PMCID: PMC8996127 DOI: 10.1039/d2ra01196d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/06/2022] [Indexed: 11/21/2022] Open
Abstract
Copper-based preservatives consisting of micronized and nanoscale copper particles have been widely used in applications for wood protection. The widespread use of these preservatives along with the potential release of copper-containing nanoparticles (Cu NPs) during the life cycle of treated wood, has raised concerns over the impacts on the environment and occupational exposure. Along with assessing the potential hazards of these materials, a critical step is determining the chemical and morphological characteristics of the copper species released from copper-treated wood. Therefore, a combination of scanning transmission electron microscopy (STEM) and electron energy-loss spectroscopy (EELS) was utilized to characterize and differentiate the released copper-containing particles based on their structures, sizing, and chemical properties. Airborne wood dust samples were collected during the abrasion and sawing of micronized copper (MC) treated wood in a laboratory testing system. Based on the signature Cu L2,3 edge of EEL spectra, three different copper species (i.e., basic copper carbonate, copper, and copper–wood complex) were identified as major components of the embedded particles in wood dust. In addition, two types of individual Cu NPs consisting of basic copper carbonate and copper were identified. The variation of morphologies and chemical properties of copper-containing particles indicates the importance of copper–wood interactions to determine the formation and distribution of copper species in wood components. Our findings will advance the fundamental understanding of their released forms, potential transformation, and environmental fate during the life cycle. A combination of analytical electron microscopy and electron energy loss spectroscopy enables effective speciation and characterization of airborne copper nanoparticles released from copper-treated wood.![]()
Collapse
Affiliation(s)
- Chen Wang
- The Health Effects Lab Division, National Institute for Occupational Safety and Health, Cincinnati, OH, 45226, USA
| | - Chaolong Qi
- Division of Field Studies and Engineering, National Institute for Occupational Safety and Health, Cincinnati, OH, 45226, USA
| |
Collapse
|
5
|
Kang S, Liang H, Qian Y, Qi C. The Composition of Emissions from Sawing Corian®, a Solid Surface Composite Material. Ann Work Expo Health 2020; 63:480-483. [PMID: 30852605 DOI: 10.1093/annweh/wxz009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 01/15/2019] [Accepted: 01/25/2019] [Indexed: 11/12/2022] Open
Abstract
We conducted detailed analyses of the composition of emissions from sawing Corian®, a solid surface composite material, in a laboratory testing system. The analyses included the aluminum content of size-selective dust samples, semivolatile organic compounds (SVOCs) in respirable dust samples, and volatile organic compounds (VOCs). The normalized respirable dust generation rate found using a Micro-Orifice Uniform Deposit Impactor was 5.9 milligrams per gram (mg g-1) suggesting that 0.59% of the mass removed from sawing Corian® becomes respirable dust. The alumina trihydrate content of the dust was consistently above 85% in most parts of the respirable size range, verifying an earlier finding that it is the dominant composition of the airborne particles of all sizes, including ultrafine particles. VOC analyses revealed that methyl methacrylate (MMA) was the most abundant compound, with a generation rate of 6.9 mg g-1 (0.69% of the mass removed from sawing Corian® became MMA vapor). The SVOC analysis only found a small amount of MMA (0.55%) in the bulk dust.
Collapse
Affiliation(s)
- Seungkoo Kang
- Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, MS: Cincinnati, OH, USA
| | - Huayan Liang
- Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, MS: Cincinnati, OH, USA
| | - Yong Qian
- Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV, USA
| | - Chaolong Qi
- Division of Applied Research and Technology, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, MS: Cincinnati, OH, USA
| |
Collapse
|
6
|
Zheng L, Kulkarni P, Birch ME, Ashley K, Wei S. Analysis of Crystalline Silica Aerosol Using Portable Raman Spectrometry: Feasibility of Near Real-Time Measurement. Anal Chem 2018; 90:6229-6239. [DOI: 10.1021/acs.analchem.8b00830] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Lina Zheng
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, United States
| | - Pramod Kulkarni
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, United States
| | - M. Eileen Birch
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, United States
| | - Kevin Ashley
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, United States
| | - Shijun Wei
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226, United States
| |
Collapse
|
7
|
Sisler JD, Qi C, McKinney W, Shaffer J, Andrew M, Lee T, Thomas T, Castranova V, Mercer RR, Qian Y. Physical chemical properties and cell toxicity of sanding copper-treated lumber. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2018; 15:311-321. [PMID: 29300681 DOI: 10.1080/15459624.2018.1424339] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
To protect against decay and fungal invasion into the wood, the micronized copper, copper carbonate particles, has been applied in the wood treatment in recent years; however, there is little information on the health risk associated with sanding micronized copper-treated lumber. In this study, wood dust from the sanding of micronized copper azole-treated lumber (MCA) was compared to sanding dust from solubilized copper azole-treated wood (CA-C) and untreated yellow pine (UYP). The test found that sanding MCA released a much higher concentration of nanoparticles than sanding CA-C and UYP, and the particles between about 0.4-2 µm from sanding MCA had the highest percentage of copper. The percentage of copper in the airborne dust from sanding CA-C had a weak dependency on particle size and was lower than that from sanding MCA. Nanoparticles were seen in the MCA PM2.5 particles, while none were detected in the UYP or CA-C. Inductively coupled plasma mass spectrometry (ICP-MS) analysis found that the bulk lumber for MCA and CA-C had relatively equal copper content; however, the PM2.5 particles from sanding the MCA had a higher copper concentration when compared to the PM2.5 particles from sanding UYP or CA-C. The cellular toxicity assays show that exposure of RAW 264.7 macrophages (RAW) to MCA and CA-C wood dust suspensions did not induce cellular toxicity even at the concentration of 200 µg PM2.5 wood dust/mL. Since the copper from the treated wood dust can leach into the wood dust supernatant, the supernatants of MCA, CA-C and UYP wood dusts were subjected to the cellular toxicity assays. The data showed that at the higher concentrations of copper (≥5 µg/ml), both MCA and CA-C supernatants induced cellular toxicity. This study suggests that sanding MCA-treated lumber releases copper nanoparticles and both the MCA and CA-C-treated lumber can release copper, which are potentially related to the observed in vitro toxicity.
Collapse
Affiliation(s)
- Jennifer D Sisler
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| | - Chaolong Qi
- b National Institute for Occupational Safety and Health, Division of Applied Research & Technology , Engineering and Physical Hazards Branch , Cincinnati , Ohio
| | - Walter McKinney
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| | - Justine Shaffer
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| | - Michael Andrew
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| | - Taekhee Lee
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| | - Treye Thomas
- c U.S. Consumer Product Safety Commission , Rockville , Maryland
| | - Vincent Castranova
- d School of Pharmacy , West Virginia University , Morgantown , West Virginia
| | - Robert R Mercer
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| | - Yong Qian
- a National Institute for Occupational Safety and Health , Health Effects Laboratory Division , Morgantown , West Virginia
| |
Collapse
|
8
|
Alexander BM, Esswein EJ, Gressel MG, Kratzer JL, Feng HA, Miller AL, Cauda E, Heil G. Evaluation of an improved prototype mini-baghouse to control the release of respirable crystalline silica from sand movers. JOURNAL OF OCCUPATIONAL AND ENVIRONMENTAL HYGIENE 2018; 15:24-37. [PMID: 29053936 DOI: 10.1080/15459624.2017.1376068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The OSHA final rule on respirable crystalline silica (RCS) will require hydraulic fracturing companies to implement engineering controls to limit workers' exposure to RCS. RCS is generated by pneumatic transfer of quartz-containing sand during hydraulic fracturing operations. Chronic inhalation of RCS can lead to serious disease, including silicosis and lung cancer. NIOSH research identified at least seven sources where RCS aerosols were generated at hydraulic fracturing sites. NIOSH researchers developed an engineering control to address one of the largest sources of RCS aerosol generation, RCS escaping from thief hatches on the top of sand movers. The control, the NIOSH Mini-Baghouse Retrofit Assembly (NMBRA), mounts on the thief hatches. Unlike most commercially available engineering controls, the NMBRA has no moving parts and requires no power source. This article details the results of an evaluation of generation 3 of the NMBRA at a sand mine in Arkansas from May 19-21, 2015. During the evaluation, 168 area air samples were collected at 12 locations on and around a sand mover with and without the NMBRA installed. Analytical results for respirable dust and RCS indicated the use of the NMBRA effectively reduced concentrations of both respirable dust and RCS downwind of the thief hatches. Reductions of airborne respirable dust were estimated at 99+%; reductions in airborne RCS ranged from 98-99%. Analysis of bulk samples of the dust showed the likely presence of freshly fractured quartz, a particularly hazardous form of RCS. Use of an improved filter fabric and a larger area of filter cloth led to substantial improvements in filtration and pressures during these trials, as compared to the generation 2 NMBRA. Planned future design enhancements, including a weather cover, will increase the performance and durability of the NMBRA. Future trials are planned to evaluate the long-term operability of the technology.
Collapse
Affiliation(s)
- Barbara M Alexander
- a National Institute for Occupational Safety and Health , Division of Applied Research and Technology , Cincinnati , Ohio
| | - Eric J Esswein
- b National Institute for Occupational Safety and Health , Western States Division , Denver , Colorado
- c University of the Witwatersrand, School of Public Health , Johannesburg , South Africa
| | - Michael G Gressel
- a National Institute for Occupational Safety and Health , Division of Applied Research and Technology , Cincinnati , Ohio
| | - Jerry L Kratzer
- a National Institute for Occupational Safety and Health , Division of Applied Research and Technology , Cincinnati , Ohio
| | - H Amy Feng
- a National Institute for Occupational Safety and Health , Division of Applied Research and Technology , Cincinnati , Ohio
| | - Arthur L Miller
- d National Institute for Occupational Safety and Health , Spokane Mining Research Division , Spokane , Washington
| | - Emanuele Cauda
- e National Institute for Occupational Safety and Health , Pittsburgh Mining Research Division , Pittsburgh , Pennsylvania
| | - Graeham Heil
- a National Institute for Occupational Safety and Health , Division of Applied Research and Technology , Cincinnati , Ohio
| |
Collapse
|
9
|
Qi C, Echt A, Gressel MG. The Generation Rate of Respirable Dust from Cutting Fiber Cement Siding Using Different Tools. Ann Work Expo Health 2017; 61:218-225. [PMID: 28395343 DOI: 10.1093/annweh/wxw010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 11/28/2016] [Indexed: 11/14/2022] Open
Abstract
This article describes the evaluation of the generation rate of respirable dust (GAPS, defined as the mass of respirable dust generated per unit linear length cut) from cutting fiber cement siding using different tools in a laboratory testing system. We used an aerodynamic particle sizer spectrometer (APS) to continuously monitor the real-time size distributions of the dust throughout cutting tests when using a variety of tools, and calculated the generation rate of respirable dust for each testing condition using the size distribution data. The test result verifies that power shears provided an almost dust-free operation with a GAPS of 0.006 g m-1 at the testing condition. For the same power saws, the cuts using saw blades with more teeth generated more respirable dusts. Using the same blade for all four miter saws tested in this study, a positive linear correlation was found between the saws' blade rotating speed and its dust generation rate. In addition, a circular saw running at the highest blade rotating speed of 9068 rpm generated the greatest amount of dust. All the miter saws generated less dust in the 'chopping mode' than in the 'chopping and sliding' mode. For the tested saws, GAPS consistently decreased with the increases of the saw cutting feed rate and the number of board in the stack. All the test results point out that fewer cutting interactions between the saw blade's teeth and the siding board for a unit linear length of cut tend to result in a lower generation rate of respirable dust. These results may help guide optimal operation in practice and future tool development aimed at minimizing dust generation while producing a satisfactory cut.
Collapse
Affiliation(s)
- Chaolong Qi
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS: R5, Cincinnati, OH 45226, USA
| | - Alan Echt
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS: R5, Cincinnati, OH 45226, USA
| | - Michael G Gressel
- Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS: R5, Cincinnati, OH 45226, USA
| |
Collapse
|
10
|
Chubb LG, Cauda EG. Characterizing Particle Size Distributions of Crystalline Silica in Gold Mine Dust. AEROSOL AND AIR QUALITY RESEARCH 2017; 17:24-33. [PMID: 28217139 PMCID: PMC5315417 DOI: 10.4209/aaqr.2016.05.0179] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Dust containing crystalline silica is common in mining environments in the U.S. and around the world. The exposure to respirable crystalline silica remains an important occupational issue and it can lead to the development of silicosis and other respiratory diseases. Little has been done with regard to the characterization of the crystalline silica content of specific particle sizes of mine-generated dust. Such characterization could improve monitoring techniques and control technologies for crystalline silica, decreasing worker exposure to silica and preventing future incidence of silicosis. Three gold mine dust samples were aerosolized in a laboratory chamber. Particle size-specific samples were collected for gravimetric analysis and for quantification of silica using the Microorifice Uniform Deposit Impactor (MOUDI). Dust size distributions were characterized via aerodynamic and scanning mobility particle sizers (APS, SMPS) and gravimetrically via the MOUDI. Silica size distributions were constructed using gravimetric data from the MOUDI and proportional silica content corresponding to each size range of particles collected by the MOUDI, as determined via X-ray diffraction and infrared spectroscopic quantification of silica. Results indicate that silica does not comprise a uniform proportion of total dust across all particle sizes and that the size distributions of a given dust and its silica component are similar but not equivalent. Additional research characterizing the silica content of dusts from a variety of mine types and other occupational environments is necessary in order to ascertain trends that could be beneficial in developing better monitoring and control strategies.
Collapse
Affiliation(s)
- Lauren G. Chubb
- Pittsburgh Mining Research Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Pittsburgh, PA 15236, USA
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15261, USA
| | - Emanuele G. Cauda
- Pittsburgh Mining Research Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Pittsburgh, PA 15236, USA
| |
Collapse
|
11
|
Qi C, Echt A, Murata TK. Characterizing Dust from Cutting Corian®, a Solid-Surface Composite Material, in a Laboratory Testing System. ANNALS OF OCCUPATIONAL HYGIENE 2016; 60:638-42. [PMID: 26872962 DOI: 10.1093/annhyg/mew005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 01/13/2016] [Indexed: 12/30/2022]
Abstract
We conducted a laboratory test to characterize dust from cutting Corian(®), a solid-surface composite material, with a circular saw. Air samples were collected using filters and direct-reading instruments in an automatic laboratory testing system. The average mass concentrations of the total and respirable dusts from the filter samples were 4.78±0.01 and 1.52±0.01mg cm(-3), respectively, suggesting about 31.8% mass of the airborne dust from cutting Corian(®) is respirable. Analysis of the metal elements on the filter samples reveals that aluminum hydroxide is likely the dominant component of the airborne dust from cutting Corian(®), with the total airborne and respirable dusts containing 86.0±6.6 and 82.2±4.1% aluminum hydroxide, respectively. The results from the direct-reading instruments confirm that the airborne dust generated from cutting Corian(®) were mainly from the cutting process with very few particles released from the running circular saw alone. The number-based size distribution of the dusts from cutting Corian(®) had a peak for fine particles at 1.05 µm with an average total concentration of 871.9 particles cm(-3), and another peak for ultrafine particles at 11.8nm with an average total concentration of 1.19×10(6) particles cm(-3) The small size and high concentration of the ultrafine particles suggest additional investigation is needed to study their chemical composition and possible contribution to pulmonary effect.
Collapse
Affiliation(s)
- Chaolong Qi
- Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS: R5, Cincinnati, OH 45226, USA
| | - Alan Echt
- Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS: R5, Cincinnati, OH 45226, USA
| | - Taichi K Murata
- Division of Applied Research and Technology, Engineering and Physical Hazards Branch, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, 1090 Tusculum Ave, MS: R5, Cincinnati, OH 45226, USA
| |
Collapse
|