https://zh.wikipedia.org/zh-hk/2019%E6%96%B0%E5%9E%8B%E5%86%A0%E7%8B%80%E7%97%85%E6%AF%92
Virus size 大概100nm~0.1um~0.0001mm
P2
Efficiency
94% (Particles to 0.3μm micron = 0.0003mm size)
Penetration
Not more than 6%
Application
Toxic dusts, including welding fumes and asbestos
P3
Efficiency
99.95% (Particles to <0.3μm micron =less than 0.0003mm size)
Penetration
Not more than 0.05%
Toxic dusts including asbestos, welding fumes (Only achieved with PAPR or Full Face)
就咁睇P3應該係okay