In the context of mechanical wood processing, the sanding process with powered hand-held belt sander is considered as significant source of wood dust emissions. The use of integral dust extraction unit is one of the basic engineering controls to prevent the spread of dust in the working atmosphere during sanding wood with hand-held belt sander. However, practical experiences indicate that the efficiency of the filter bag attachment is usually insufficient, especially when sanding wood with a finer abrasive grain. The main goal of the diploma thesis was to evaluate the efficiency of integral dust extraction system during sanding wood with a powered hand-held belt sander. The evaluation of the efficiency was based on a comparison of the values of the wood dust mass concentration in the operator's breathing zone using the integral dust extraction system of the sander and without the use of a dust collection box. The results have demonstrated that personal exposure to wood dust can be significantly reduced by using the dust collection box while sanding wood with powered hand-held belt sander. Nevertheless, personal exposure could not be prevented completely by integral dust extraction system so the supplemental exposure control such as respiratory protective equipment would be required.