Personal protective equipment against infectious respiratory diseases

The effectiveness of the personal protective equipment (PPE) is critical to prevent infection arising from severe acute respiratory syndrome and influenza. The objectives of this research were to establish a sound scientific understanding of the protective performances and psycho-physiological roles of different types of PPE in use.;The study of masks was carried out to investigate the in-vivo effects of N95 and surgical masks commonly available with or without nano-functional treatments, as well as two types of new masks with exhaust valves and holes (masks A and B). Five healthy male and five healthy female participants performed intermittent exercise on a treadmill while wearing the protective masks in a climate chamber controlled at an air temperature of 25°C and a relative humidity of 70%. During this period, the a KCl-Fluorescein solution as a surrogate for a viral solution was sprayed onto the masks twice at a distance of 100 cm every 10 minutes for 14 times in total.;The results showed that N95 respirators had significantly lower air permeability and water vapor permeability, but significantly higher filtration efficiency if compared with surgical masks. Nano-masks show stronger water repellency and antibacterial activities, but no difference in usability, compared with normal N95 and surgical masks. Both masks A and B had near or over 99% protective efficiency achieved simply by locating the breathing pathways to the back of mask. The tested masks can induce significantly different temperatures and humidity in the microclimates of each mask, which have profound influences on heart rate, thermal stress and subjective perception of discomfort.;PPE wear study was performed to examine the effects of wearing five types of PPE on the physiological stresses and the subjective sensations in a simulated environment closely replicating health care workers. Ten healthy subjects carried out the simulation including exercising on a treadmill, working on a computer, and moving a mannequin. The results demonstrate higher physiological and psychological stresses to the wearer can be posed when wearing the PPEI and 2 ensembles. The properties and design, air-tightness, weight and construction contribute to different stress state of PPE.;Impact of fabric moisture transport properties on physiological responses and computer simulations to develop an overall understanding of the physical mechanism have been further studied.;Through this systematic study, an overall evaluation system of mask and PPE performance has been developed for evaluating scientifically the areas of protection, physiological stresses and subjective comfort.