The Annals of occupational hygiene
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Flow and containment characteristics of a sash-less, variable-height inclined air-curtain fume hood.
To increase containment efficiency and reduce energy consumption, a sash-less, variable-height inclined air-curtain fume hood (sIAC hood) was developed and tested by a laser-assisted flow visualization technique and tracer-gas detection method. This novel design requires neither sash nor baffle. The sIAC hood employed the inclined push-pull air-curtain technique and two deflection plates installed on the side walls of the hood to induce a tetra-vortex flow structure. ⋯ The results of a static test showed that small face velocities of 0.25 and 0.16 m s(-1) were enough to obtain nearly null leakage levels for low and tall pollutant sources. The results of a traversing plate test showed that the face velocity, 0.32 m s(-1), would cause negligibly small leakage levels. The sIAC hood could obtain significantly higher containment efficiency than a conventional hood by operating at a face velocity significantly lower than that of conventional hoods.
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This study provides an understanding of heat and mass transfer through materials exposed to hot liquid splash, a relatively unexplored hazard in the safety clothing industry. Selected fabrics and layered systems were exposed to three hot liquids to study the effects of hot liquids and configuration. ⋯ The preliminary testing demonstrated that mass transfer of the hot liquid through the fabric is the main factor contributing to burn injury. Key factors that determine the level of protection that a fabric system provides are summarized.
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Benford's law is the contra-intuitive empirical observation that the digits 1-9 are not equally likely to appear as the initial digit in numbers resulting from the same phenomenon. Manipulated, unrelated, or created numbers usually do not follow Benford's law, and as such this law has been used in the investigation of fraudulent data in, for example, accounting and to identify errors in data sets due to, for example, data transfer. We describe the use of Benford's law to screen occupational hygiene measurement data sets using exposure data from the European rubber manufacturing industry as an illustration. ⋯ Evaluation indicated only small deviations from the expected 1BL and 2BL distributions for the data sets collated by the UK HSE and industry (BRMA), respectively, while for the MEGA data larger deviations were observed. To a large extent the latter could be attributed to imputation and replacement by a constant of n-nitrosamine measurements below the limit of detection, but further evaluation of these data to determine why other deviations from 1BL and 2BL expected distributions exist may be beneficial. Benford's law is a straightforward and easy-to-implement analytical tool to evaluate the quality of occupational hygiene data sets, and as such can be used to detect potential problems in large data sets that may be caused by malcontent a priori or a posteriori manipulation of data sets and by issues like treatment of observations below the limit of detection, rounding and transfer of data.
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Review Case Reports
Lethal carbon monoxide poisoning in wood pellet storerooms--two cases and a review of the literature.
The installation of wood pellet heating as a cost-effective and climatically neutral source of energy for private households has increased steadily in recent years. We report two deaths that occurred within the space of about a year in wood pellet storerooms of private households in German-speaking countries and were investigated by forensic medical teams. This is the first report of fatalities in this special context as is shown in the literature review. ⋯ It is therefore a new finding that fatal accidents may also occur in the wood pellet storerooms of private households. We show that significant CO concentrations can build up even when these rooms are ventilated in accordance with the regulations and that such levels may cause the death of healthy persons, as described in the following. As the safety recommendations from the wood pellet industry are inadequate, we consider that further fatal accidents are likely to occur and recommend urgent revision of the safety regulations.
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Increased thermal perceptions that affect comfort are a leading reason for intolerance to wearing respiratory protective equipment. Despite their popularity and use for decades, relatively little is known about the thermal burden imposed by the use of N95 filtering facepiece respirators (FFR) at normal work rates. Twenty healthy subjects exercised at a low-moderate work rate for 1 and 2 h while wearing four models of N95 FFR (two with an exhalation valve) as core and skin temperatures were monitored wirelessly. ⋯ Facial skin temperature under the FFR was significantly increased over baseline values (P < 0.001). Wearing N95 FFR for up to 2 h at a low-moderate work rate does not impose a significant thermal burden on core temperature and uncovered facial skin temperature but significantly increases the temperature of the facial skin that is covered by the FFR. Perceptions of increased body heat when wearing N95 FFR under the test conditions are likely not due to effects on core temperature but may relate more to warming of the facial skin covered by the respirator and warming of the inspired air.