| 摘要 |
A four sided dustproof mask is provided, which can secure the dust filtration area about the size of the dust mask filtering paper to the maximum. A four sided dustproof mask comprises: a top filter paper(11) covering the nasal region; a bottom filter paper(12) covering the jaw region; and a center extrusion filter paper(40) in which the bottom filter paper is adhered. Both ends of top and bottom filter papers are adhered corresponding to the center displayed on both ends of the curved folding line(41) dividing the center extrusion filter paper. The curved folding line is protruded in the form of the regular length straight-line portion(41a) from the center. The center extrusion filter paper has the structure of being protruded in the dome shape.
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