Under normal circumstances, disposable medical masks and medical surgical masks are for limited use, and the cumulative use does not exceed 8 hours; the use of masks by occupational exposure personnel does not exceed 4 hours. After the use time of the mask reaches the upper limit, it cannot be used any more.
The mask should be replaced in time if the following situations occur: the mask is damaged or damaged; the mask is contaminated (for example, it is stained with foreign objects such as blood stains or droplets); it has been used in an isolation ward or in contact with the patient; the mask is damp; there is a peculiar smell in the mask; respiratory resistance Significant increase; the mask cannot be closely attached to the face.