ABSTRACT
Lately is greatly increasing the number of professional diseases of workers respirational organs especially at coal industry (Medvedev 2005). Such situation has turned out as a result of the whole rank of some negative factors but the heaviest one is erroneous calculation of value of dust load. The errors appear first of all because of doubtful data of dust concentration in the air of working zone, volume of workers’ lungs aeration, wrong estimation of coefficient of delivery unhealthy aerosol into respirator. Thus at the mines the protective devices with different protective efficiency are used whereas this fact isn’t accounted while calculation of dust load (Instructions... 2003). Besides the dust-proof DIPRO’s type (with the filtering half mask or isolated half mask with shifting filters) is ignored; class of protection (high – FFP3, middle – FFP2, low – FFP1), the volume of respirative resistance to air flow etc. So at working process the filtering cell its resistance to the half mask space because of impenetrability on the obturation stripe (Figure 1).
