Impact of medical face mask wear on bacterial filtration efficiency and breathability

Wearing a medical mask for longer than the manufacturer’s recommended 4 h would reduce the number of masks used and limit their environmental impact. The objective of this study was to determine if a medical mask could be worn for an extended period of time by simulating different wearing conditions. A simulator was developed to reproducibly study various experimental conditions (wearing time, breathing pattern, mask fit, inhaled air humidity) by placing the masks on a 3D replica of the upper airways connected to a respiratory pump. Medical mask performance was determined by assessing normative requirements: bacterial filtration and breathability. No impact on performance was observed for wearing times from 2 h to 8 h. Similarly, when simulating moderate respiratory effort or at rest, various humidity levels in the inhaled air or different fitting conditions, no influence on performance was found. These results imply that none of these experimental conditions appear to have a significant impact on mask performance. In conclusion some medical masks can be used for up to 8 h under different wearing conditions without significant decrease in their bacterial filtration and breathability performance. This recommendation of a possible rise of usage duration would limit mask waste, and thus environmental consequence.