Ordinary PM 2.5 masks for protection against new coronaviruses are not ideal. PM 2.5 masks are masks that can effectively filter PM 2.5 particles, standard PM 2.5 masks, can effectively filter the air haze, viruses, bacteria, dust mites, pollen and other tiny particles, but the various PM 2.5 masks currently sold on the market, good and bad, and do not meet the standard, many are cotton, set a filter cloth, this isolation effect is certainly not. To determine whether it is a standard PM 2.5 mask, the main look at its implementation of the standard, if the mask is marked with respiratory protection (N9X or KN9X), the standard number GB 2626-20063, can also be used to protect against new coronaviruses.