Last data update: May 13, 2024. (Total: 46773 publications since 2009)
Records 1-5 (of 5 Records) |
Query Trace: Woskie SR[original query] |
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The effect of the body wake and operator motion on the containment of nanometer-scale airborne substances using a conventional fume hood and specially designed enclosing hood: a comparison using computational fluid dynamics
Shen C , Dunn KH , Woskie SR , Bennett JS , Ellenbecker MJ , Dandy DS , Tsai CSJ . J Nanopart Res 2022 24 (4) Airborne substances in the nanoparticle size range would mostly follow the primary airflow patterns, which emphasizes the importance of understanding the airflow dynamics to effectively control exposures to toxic airborne substances such as nanometer-sized particles. Chemical fume hoods are being utilized as primary controls for worker exposure to airborne substances including nanometer-scale materials due to their overall availability and history of effective contaminant. This study evaluates the impact of the body wake on the containment performance of a conventional constant air volume (CAV) and a new “nano” ventilated enclosing hood using numerical methods. Numerical studies have been performed to predict leaks of nanomaterials handled inside the hood. We further performed experiments in this study to validate the velocity fields predicted by the computational fluid dynamic (CFD) models and to provide a basis for evaluating the impact of the human body on fume hood containment performance. Using these validated models, the effects of the motion of the arms moving out of the hood were simulated using CFD to assess how one of the common actions of an operator/user may affect containment. Results of our simulations show that areas near the hood side airfoils and directly behind the sash are more likely to concentrate contaminants released inside the hood and potentially result in leakage based on internal airflow patterns. These areas are key to monitor when assessing fume hood containment along with the operator/mannequin breathing zone to get an understanding of potential leak areas which might contribute to operator exposure as well as exposure to others inside the laboratory. © 2022, The Author(s), under exclusive licence to Springer Nature B.V. |
Evaluation of leakage from fume hoods using tracer gas, tracer nanoparticles and nanopowder handling test methodologies
Dunn KH , Tsai CS , Woskie SR , Bennett JS , Garcia A , Ellenbecker MJ . J Occup Environ Hyg 2014 11 (10) D164-73 The most commonly reported control used to minimize workplace exposures to nanomaterials is the chemical fume hood. Studies have shown, however, that significant releases of nanoparticles can occur when materials are handled inside fume hoods. This study evaluated the performance of a new commercially available nano fume hood using three different test protocols. Tracer gas, tracer nanoparticle, and nanopowder handling protocols were used to evaluate the hood. A static test procedure using tracer gas (sulfur hexafluoride) and nanoparticles as well as an active test using an operator handling nanoalumina were conducted. A commercially available particle generator was used to produce sodium chloride tracer nanoparticles. Containment effectiveness was evaluated by sampling both in the breathing zone (BZ) of a mannequin and operator as well as across the hood opening. These containment tests were conducted across a range of hood face velocities (60, 80, and 100 ft/min) and with the room ventilation system turned off and on. For the tracer gas and tracer nanoparticle tests, leakage was much more prominent on the left side of the hood (closest to the room supply air diffuser) although some leakage was noted on the right side and in the BZ sample locations. During the tracer gas and tracer nanoparticle tests, leakage was primarily noted when the room air conditioner was on for both the low and medium hood exhaust airflows. When the room air conditioner was turned off, the static tracer gas tests showed good containment across most test conditions. The tracer gas and nanoparticle test results were well correlated showing hood leakage under the same conditions and at the same sample locations. The impact of a room air conditioner was demonstrated with containment being adversely impacted during the use of room air ventilation. The tracer nanoparticle approach is a simple method requiring minimal setup and instrumentation. However, the method requires the reduction in background concentrations to allow for increased sensitivity. |
Retrospective assessment of exposure to chemicals for a microelectronics and business machine manufacturing facility
Fleming DA , Woskie SR , Jones JH , Silver SR , Luo L , Bertke SJ . J Occup Environ Hyg 2013 11 (5) 292-305 A retrospective exposure assessment was performed for use in a health outcomes study of a facility manufacturing circuit boards, business machines and other equipment during the years 1969-2002. A matrix was developed identifying chemical use by department-year based on company-provided information. Use of six chemical agents (fiberglass, lead, methylene chloride, methyl chloroform, perchloroethylene and trichloroethylene) and six chemical classes (acid-base, aromatic hydrocarbons, chlorinated hydrocarbons, other hydrocarbons, chlorofluorocarbons and metals), and general (including unspecified) chemicals was identified. The matrix also contained an assignment for each department-year categorizing the potential for use of chemicals as negligible, intermittent/incidental, or routine. These department-based exposure matrix data were combined with work history data to provide duration of potential chemical use for workers. Negligible, intermittent/incidental or routine extent-of-chemical-use categories comprised 42.6%, 39.4% and 17.9% respectively, of total person-years of employment. Cumulative exposure scores were also developed, representing a relative measure of the cumulative extent of potential exposure to the six chemical agents, six chemical classes, and general (including unspecified) chemicals. Additionally, the study period was divided into manufacturing eras showing trends in chemical use, and showing that process use of trichloroethylene and methylene chloride ended in the mid-1980s and the mid-1990s, respectively. This approach may be useful in other assessments addressing a variety of chemicals, and with data constraints common to retrospective chemical exposure studies. |
World Trade Center disaster: assessment of responder occupations, work locations, and job tasks
Woskie SR , Kim H , Freund A , Stevenson L , Park BY , Baron S , Herbert R , de Hernandez MS , Teitelbaum S , de la Hoz RE , Wisnivesky JP , Landrigan P . Am J Ind Med 2011 54 (9) 681-695 BACKGROUND: To date there have been no comprehensive reports of the work performed by 9/11 World Trade Center responders. METHODS: 18,969 responders enrolled in the WTC Medical Monitoring and Treatment Program were used to describe workers' pre-9/11 occupations, WTC work activities and locations from September 11, 2001 to June 2002. RESULTS: The most common pre-9/11 occupation was protective services (47%); other common occupations included construction, telecommunications, transportation, and support services workers. 14% served as volunteers. Almost one-half began work on 9/11 and >80% reported working on or adjacent to the "pile'' at Ground Zero. Initially, the most common activity was search and rescue but subsequently, the activities of most responders related to their pre-9/11 occupations. Other major activities included security; personnel support; buildings and grounds cleaning; and telecommunications repair. CONCLUSIONS: The spatial, temporal, occupational, and task-related taxonomy reported here will aid the development of a job-exposure matrix, assist in assessment of disease risk, and improve planning and training for responders in future urban disasters. Am. J. Ind. Med. 54:681-695, 2011. (C) 2011 Wiley-Liss, Inc. |
Understanding workplace processes and factors that determine exposures to engineered nanomaterials
Woskie SR , Bello D , Virji MA , Stefaniak AB . Int J Occup Environ Health 2010 16 (4) 365-77 There is a critical need to understand the factors that influence engineered nannomaterial (ENM) exposures in the workplace. Such an understanding would aid in: identifying and prioritizing control measures; targeting future exposure measurements; and predicting worker exposures for work scenarios. This information could also be used in epidemiological studies. We propose a multitiered model in which information on exposure factors can be obtained at the macrolevel (examining differences in exposures between differenct ENM sectors or product types); the midlevel (examining differences in exposures between workplaces within the same ENM sector or product type); and the microlevel (examining differences in exposure between tasks or between ENM types during the same task). Further, within the microlevel, potential exposure factors are defined by a source-receptor model. We recommend that auxiliary data be collected systematically, along with exposure measurements, to enable analysis of exposure factors as well as the pooling of data across studies. |
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