It can not deny that the absolute performance is low as compared with DS1 etc. of the international standard. However, this "mask" is enough if it is not "working in a closed room filled with fine particles" but simply when there is a lot of dust. It is easy to wash and recycle, and it is easier to use than a nonwoven type as it is not clogged by moisture of exhalation if you put a gauze inside. Benefits are high if used in consideration of the risk balance of "whether dust that scatters is dangerous" and "cost". Dustproof mask made of nonwoven fabric Honorable workers are highly praised in terms of ease of breathing. Since there is one rubber string, it is difficult to fix the face, and the point that I feel painful because the tension becomes stronger is wanted improvement.