Yesterday a parent asked me: which mask is good to wear? I think this may be the majority of people concerned about the issue, especially now that the flu season and haze frequent days, I summarized and organized. Currently on the market masks are divided into the following types: cotton masks, medical masks, N95 masks, activated carbon masks. 1, general cotton masks or gauze masks: can only filter larger particles, only suitable for ordinary cleaning work. 2, surgical masks: can block more than 90% of 5 micron particles, should be replaced every day, but broken or dirty should be replaced immediately, suitable for colds, fevers, coughs and other respiratory symptoms, go to hospitals, movie theaters, and other places not ventilated to use, but can not filter PM <2, 5 particles 3, activated carbon masks: organic gases can be adsorbed and toxic dust, does not have a bactericidal function, the need to breathe or can not be adsorbed when the odor is laborious Should be replaced immediately, applicable to paint spraying operations or spraying pesticides. 4, N95 mask: can block more than 95% of the sub-micron particles, breathing impedance is high, not suitable for the general public to wear for a long time, and should avoid repeated use. We can see that the haze weather, PM2, 5 particles only N95 mask can be filtered, but because it is too dense, breathing resistance is high, is not suitable for long time to wear, so we try to minimize the haze weather to go out.