Rumors:

The antiviral effect of the mask is not directly related to the thickness of the mask.

The size of coronavirus is only about 100 nanometer, but the virus does not exist alone in the air. They are always attached to some fine particles or droplets formed when sneezing. If the mask can filter out these tiny particles and droplets, it can significantly reduce the inhalation of viruses. The thickness of medical surgical mask is small, but the filtration effect of melt-blown nonwovens in the middle is very high. Melt-blown nonwovens are formed by interlacing superfine polypropylene fibers and finishing by electrostatic electret. When the mask wearer inhales air, the meltblown layer captures fine particles and droplets in the inhaled air through inertial collision, interception and diffusion mechanisms, especially electrostatic attraction, thus preventing the virus from invading. Therefore, the medical surgical mask, which consists of three layers: the surface water-blocking layer, the middle melt-blown filter layer and the skin-adhering moisture-absorbing layer, can effectively block the inhalation of viruses.

Although the cotton gauze mask is composed of many layers of gauze, it looks very thick, but it can't stop the virus from invading. Compared with melt-blown nonwovens, gauze has larger pores, so it is difficult to play the role of inertial collision and interception, and static electricity can not stay on the electrode and filter out most fine particles. On the other hand, gauze is usually made of cotton fiber, which is hydrophilic and hygroscopic. When the mask wearer inhales air, some droplets are blocked on the mask surface. However, it will penetrate inward by virtue of the hydrophilicity of the fiber, so the effect of preventing virus invasion is not good.

Can wearing two medical surgical masks at a time have better anti-virus effect? It's totally unnecessary. Wearing two medical surgical masks at a time will not improve the efficiency of intercepting fine particles and droplets, but will greatly increase the respiratory resistance and make it difficult for the wearer to breathe.

From the above analysis, it can be seen that the thickness of the mask is not proportional to the filtration capacity, and the thickness of the mask will increase the resistance of breathing gas.

Rumor expert: Associate Professor, Textile College, Donghua University, Wu Haibo

Expert: Professor Jin Xiangyu from Textile College of Donghua University.

Co-produced by China and China Textile Engineering Society.