PM 2.5 masks cannot prevent new coronaviruses. PM 2.5 masks can only stop air pollution suspended particles from entering the respiratory system, the volume of viruses is much smaller than PM 2.5, so these anti-haze masks and ordinary cotton masks are ineffective. Prevention of coronavirus can choose to apply surgical masks and medical protective masks to prevent new coronavirus pneumonia, it is not necessary to wear N95 masks, with medical surgical masks, can also block most of the virus stuck on the droplets from entering the respiratory tract.