It is important that the time integral of the efficiency be used and that the start up of the operation be included since efficiencies tended to approach 100% rather quickly. Further study is needed to confirm the functional relationship for more realistic laboratory simulations and field studies. For the surgical mask, the concentration was determined under different conditions (office work, slow walking, and fast walking). However, its true potential for application lies in monitoring and measurement since duct concentrations are easily obtained. In this study, the carbon dioxide concentration in the breathing zone was measured while wearing a surgical mask, a KN95 and a cloth mask. Conventionally, the 'breathing zone' is defined as the zone within a 0.3 m (or 10 inches) radius of a worker's nose and mouth, and it has been generally assumed that a contaminant in the breathing zone is homogeneous and its concentration is equivalent to the concentration inhaled by the worker. One may as well simulate the concentration directly. The author concludes that the difficulty in predicting capture efficiency for actual operation makes its use in modelling questionable. The use of capture efficiency as a design parameter appeared superior to the capture velocity concept in that a stronger relationship exists with the parameter of interest, that is, the exposure. The results suggested that the time integral of capture efficiency is inversely proportional to the instantaneous breathing zone concentration. This theory was examined experimentally with a mannequin and several local exhaust hoods. A zone controlling method is deemed suitable as an operating method of a movable air purifier to reduce the concentration of fine particulate matter in the breathing zone of occupants.The theory was presented that if a worker's breathing zone concentration were proportional to the average room concentration at a given time, then the breathing zone concentration at that time should be directly proportional to the contaminant flow rate and inversely proportional to the time averaged capture efficiency. On the other hand, a real-time occupant tracking method may face a threshold due to the moving path of an air purifier and changes in the number of occupants. The results showed the concentration of fine particulate matter around the breathing zone of the occupants had decreased by about 51 μg/m 3 compared to the surrounding concentration in terms of the operating method in which an air purifier tracks occupants in real-time, and a decrease of about 68 μg/m 3 in terms of the operating method in which an air purifier controls the zone. The study evaluated the purifiers’ performance in reducing the concentration of fine particulate matter in the occupants’ breathing zone according to the operation method in which a movable air purifier responds to the movement of occupants. Accordingly, this study analyzed changes in the concentration of indoor fine particulate matter through an experiment according to the discharging method and location of a fixed air purifier considering the inflow route of fine particulate matter into the body and their harmfulness. isocyanurate exposure was only affected by its paint concentration (p 0.003). There is a limit to controlling the concentration of fine particulate matter of the overall space where an air purifier is fixed in one spot as the source of indoor fine particulate matter is varied. THE EFFECT OF WORK ENVIRONMENT ON THE BREATHING-ZONE CONCENTRATIONS OF 1,6-HEXAMETHYLEN DIISOCYANATE MONOMER AND ITS OLIGOMERS IN AUTOMOTIVE REFINISHING INDUSTRY Wook Kim. However, earlier studies have not evaluated an operating method of air purifiers considering the inflow of fine particulate matter into the body or reduction performance of the concentration of fine particulate matter. In South Korea, filter-type air purifiers are used to eliminate indoor fine particulate matter, and there has been a broad range of studies on the spread of fine particulate matter and air purifiers. Fine particulate matter entering the body through breathing cause serious damage to humans.
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