The protective effect of a face mask is closely related to the working environment, such as the concentration and risk level of harmful substances. If the working environment is more complex, the service life of the half mask will be correspondingly shortened.
For example, in high temperature and high humidity environments, the material of the face mask is prone to aging and failure; In environments such as chemical laboratories and petrochemical plants, the concentration of harmful substances is high, and the material of the mask is corrosive. Therefore, the service life needs to be strictly controlled.
