2012-09-01 12:00 - Messages

Methods for calculating thermal insulation of clothing measured with a thermal manikin

There are three methods for calculating thermal insulation of clothing measured with a thermal manikin, i.e. the global method, the serial method, and the parallel method. Under the condition of homogeneous clothing insulation, these three methods yield the same insulation values. If the local heat flux is uniform over the manikin body, the global and serial methods provide the same insulation value. In most cases, the serial method gives a higher insulation value than the global method. There is a possibility that the insulation value from the serial method is lower than the value from the global method. The serial method always gives higher insulation value than the parallel method. The insulation value from the parallel method is higher or lower than the value from the global method, depending on the relationship between the heat loss distribution and the surface temperatures. Under the circumstance of uniform surface temperature distribution over the manikin body, the global and parallel methods give the same insulation value. If the constant surface temperature mode is used in the manikin test, the parallel method can be used to calculate the thermal insulation of clothing. If the constant heat flux mode is used in the manikin test, the serial method can be used to calculate the thermal insulation of clothing. The global method should be used for calculating thermal insulation of clothing for all manikin control modes, especially for thermal comfort regulation mode. The global method should be chosen by clothing manufacturers for labeling their products. The serial and parallel methods provide more information with respect to the different parts of clothing.

Source : Jianhua Huang. Theoretical Analysis of Three Methods for Calculating Thermal Insulation of Clothing from Thermal Manikin. Ann Occup Hyg (2012) 56(6): 728-735. doi:10.1093/annhyg/mer118

http://annhyg.oxfordjournals.org/content/56/6/728.abstract

 

Reduction in percutaneous injuries was concomitant with a steep market shift from conventional to safety-engineered devices

This study was to determine whether «The Needlestick Safety and Prevention Act (NSPA)» (USA) has had an effect on the rate of percutaneous injuries among hospital employees. We used a historical, prospective design, with the use of a multihospital sharps-injury database maintained by the International Healthcare Worker Safety Center at the University of Virginia. Since 1993, a group of U.S. hospitals voluntarily contributed sharps-injury surveillance data. We selected the period from 1995 through 2005, which included 23,908 injuries that occurred in 85 hospitals in 10 states. The significant decrease in the annual rates of percutaneous injuries per 100 full-time-equivalent hospital employees did not occur until the year after NSPA was signed, suggesting that this particular legislation had an independent effect.

This reduction in percutaneous injuries was concomitant with a steep market shift from conventional to safety-engineered devices and an increase in the number of OSHA citations for violation of the revised standard for handling bloodborne pathogens - two factors directly linked to the legislation. Our findings provide evidence that the NSPA contributed to the decline in percutaneous injuries among U.S. hospital workers. They also support the concept that well-crafted legislation bolstered by effective enforcement can be a motivating factor in the transition to injury-control practices and technologies, resulting in a safer work environment and workforce.

 

Source : Phillips EK, Conaway MR, et Jagger J. 2012. Percutaneous Injuries before and after the Needlestick Safety and Prevention Act. New England Journal of Medicine 2012 (366): 670-671.

http://www.nejm.org/doi/pdf/10.1056/NEJMc1110979

Intolerance to the thermal effects of PFMs leads to decreased use and concomitant decreased protection for the user

A computerized literature search was undertaken for the period 1950–2010, references selected for inclusion in the review were those that included information relating to heat, comfort, and tolerance associated with the use of PFMs. The use of protective facemasks (PFMs) negatively impacts respiratory and dermal mechanisms of human thermoregulation through impairment of convection, evaporation, and radiation processes. The relatively minor reported increases in core temperature directly attributable to the wearing of PFMs suggest that associated perceptions of increased body temperature may have a significant psychological component or that regional or global brain temperature changes are involved. Modifications in PFM structure, components, and materials might allow for improved heat dissipation and enhanced compliance with use.

Raymond J. Roberge, Jung-Hyun Kim and Aitor Coca. Protective Facemask Impact on Human Thermoregulation: An Overview. The Annals of Occupational Hygiene, Volume 56, Issue 1, Pp. 102-112. doi: 10.1093/annhyg/mer069

http://annhyg.oxfordjournals.org/content/56/1/102.full

Voir aussi: Raymond Roberge, Stacey Benson, and Jung-Hyun Kim. Thermal Burden of N95 Filtering Facepiece Respirators. Ann Occup Hyg (2012) 56(7): 808-814 first published online January 31, 2012. doi:10.1093/annhyg/mes001.  

 http://annhyg.oxfordjournals.org/content/56/7/808.abstract

 

Head-and-face dimensions for current Chinese workers show differences from the current U.S. standard headforms

The objective of this study was to develop headforms that represent today's Chinese workers. Mean facial dimensions from manual measurements were computed to target the ideal facial dimensions for each size category and used to develop 3-D digital headforms. These new headforms represent the facial size and shape distribution of current Chinese workers and may be useful for respirator research and development. The Chinese medium headform has a wider face width, shorter face length, and smaller nose protrusion when compared with the current U.S. standard headforms. Upon validation, it may be useful to incorporate these dimensions into Chinese and international respiratory protective devices standards.

*      Source: Yanyan YU, Stacey Benson et al. Digital 3-D Headforms Representative of Chinese Workers. The Annals of Occupational Hygiene, Volume 56, Issue 1, Pp. 113-122.

*       http://annhyg.oxfordjournals.org/content/56/1/113.abstract

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