PM2.5 air mask breathing filters. This is actually for single use but it can base on your actual situation. It is washable for few times before you change a new Protect your mouth and face from gases, noxious smells, pollen, smoke, dust and other harmful particles.
The first layer: filter the dust of micron
The second layer: to filter industrial pollutants, automobile exhaust, second-hand smoke pollen allergies
The third layer: activated carbon cloth, benzene and a smaller function of filtering dust microns
The fourth layer: filter density, smaller material
The fifth layer: filter out all kinds of harmful substances;