Journal of occupational and environmental hygiene
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J Occup Environ Hyg · Jan 2012
Dynamic effects on containment of air-curtain fume hood operated with heat source.
This study focused on the leakage characteristics of the air-curtain fume hood that are subject to the influences of sash movement and walk-by motion while a high temperature heat source was operated in the hood. The flow visualization and trace gas test method were used to investigate the performance of the air-curtain fume hood. An electric heater was placed in the hood to simulate the heat source. ⋯ The height of the sash opening was a crucial parameter for the containment of the air-curtain fume hood. At the sash opening lower than about 25 cm, suction velocity less than or equal to 6 m/sec was enough to make the sulfur hexafluoride leakage less than the threshold value, 0.65 ppm, suggested by the BG Chemie. The air-curtain fume hood presented a great performance to resist the effect of drafts even though there was a high temperature heat source working in the hood.
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J Occup Environ Hyg · Aug 2011
Personal PM(2.5) exposure among wildland firefighters working at prescribed forest burns in Southeastern United States.
This study investigated occupational exposure to wood and vegetative smoke in a group of 28 forest firefighters at prescribed forest burns in a southeastern U. S. forest during the winters of 2003-2005. During burn activities, 203 individual person-day PM(2.5) and 149 individual person-day CO samples were collected; during non-burn activities, 37 person-day PM(2.5) samples were collected as controls. ⋯ Overall occupational exposures to particulate matter were low, but results indicate that exposure could exceed the ACGIH®-recommended threshold limit value of 3 mg/m(3) for respirable particulate matter in a few extreme situations. Self-assessed exposure levels agreed with measured concentrations of PM(2.5). Correlation analysis shows that either PM(2.5) or CO could be used as a surrogate measure of exposure to woodsmoke at prescribed burns.
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J Occup Environ Hyg · Jul 2011
Comparative StudyImpact of three biological decontamination methods on filtering facepiece respirator fit, odor, comfort, and donning ease.
The objective of this study was to determine if ultraviolet germicidal irradiation (UVGI), moist heat incubation (MHI), or microwave-generated steam (MGS) decontamination affects the fitting characteristics, odor, comfort, or donning ease of six N95 filtering facepiece respirator (FFR) models. For each model, 10 experienced test subjects qualified for the study by passing a standard OSHA quantitative fit test. Once qualified, each subject performed a series of fit tests to assess respirator fit and completed surveys to evaluate odor, comfort, and donning ease with FFRs that were not decontaminated (controls) and with FFRs of the same model that had been decontaminated. ⋯ One of the other FFRs demonstrated a relatively small though statistically significant increase (p < 0.05) in median odor response after MHI decontamination. These data suggest that FFR users with characteristics similar to those in this study population would be unlikely to experience a clinically meaningful reduction in fit, increase in odor, increase in discomfort, or increased difficulty in donning with the six FFRs included in this study after UVGI, MHI, or MGS decontamination. Further research is needed before decontamination of N95 FFRs for purposes of reuse can be recommended.
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J Occup Environ Hyg · Feb 2011
Identification and measurement of diacetyl substitutes in dry bakery mix production.
In 2008, a company using multiple buttermilk flavorings in the production of dry bakery mixes replaced one liquid flavoring containing 15-20% diacetyl with a proprietary substitute meant to lower occupational risk for diacetyl-related bronchiolitis obliterans. Subsequently, the National Institute for Occupational Safety and Health (NIOSH) evaluated buttermilk flavoring-related exposures at this company's facility, with a focus on measuring ketones by several methods. Volatile organic compounds (VOCs) were evaluated in the headspaces of six bulk flavorings samples, including the substitute buttermilk flavoring. ⋯ Because 2,3-pentanedione, 2,3-hexanedione, and 2,3-heptanedione all share the same functional α-diketone group as diacetyl, these compounds also may share diacetyl's mechanism of toxicity. Until more is known about 2,3-pentanedione and other α-diketone compounds, they should not be assumed to be safe. Companies using artificial buttermilk flavorings should use a precautionary approach that assumes these flavorings pose a health risk and limit exposures through engineering and administrative controls and use of personal protective equipment.
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J Occup Environ Hyg · Jan 2011
Evaluation of the filtration performance of NIOSH-approved N95 filtering facepiece respirators by photometric and number-based test methods.
N95 particulate filtering facepiece respirators are certified by measuring penetration levels photometrically with a presumed severe case test method using charge neutralized NaCl aerosols at 85 L/min. However, penetration values obtained by photometric methods have not been compared with count-based methods using contemporary respirators composed of electrostatic filter media and challenged with both generated and ambient aerosols. To better understand the effects of key test parameters (e.g., particle charge, detection method), initial penetration levels for five N95 model filtering facepiece respirators were measured using NaCl aerosols with the aerosol challenge and test equipment employed in the NIOSH respirator certification method (photometric) and compared with an ultrafine condensation particle counter method (count based) for the same NaCl aerosols as well as for ambient room air particles. ⋯ Room air with fewer charged particles and an overwhelming number of neutral particles contributed to the most penetrating particle size in the 50 nm range, indicating that the charge state for the majority of test particles determines the MPPS. Data suggest that the NIOSH respirator certification protocol employing the photometric method may not be a more challenging aerosol test method. Filter penetrations can vary among workplaces with different particle size distributions, which suggests the need for the development of new or revised "more challenging" aerosol test methods for NIOSH certification of respirators.