The State Economic and Trade Commission issued in 2000 the “labor protection equipment standard (Trial)” clearly requires that “gauze masks shall not be used as dust masks”.
why? Because the general cotton gauze mask can only block part of the dust, and its dust suppression principle is mechanical filtering, that is, when the dust collides with the gauze, it passes through layers of barrier to block some large particles of dust in the sand cloth. However, some fine dust, especially the dust less than 5 microns, will pass through the mesh of gauze and enter the respiratory system. The dust less than 5 microns can directly enter the alveoli, which has the greatest impact on human health. Wearing more layers will not enhance the protective effect. Therefore, the cotton yarn mask can not play a dust-proof role. Source: Occupational Health Network