@article {Zha99, author = {Mengyi Zha and Jude Alsarraj and Brandon Bunch and David Venzon}, title = {Impact on the fitness of N95 masks with extended use/limited reuse and dry heat decontamination}, volume = {70}, number = {1}, pages = {99--103}, year = {2022}, doi = {10.1136/jim-2021-001908}, publisher = {BMJ Publishing Group Limited}, abstract = {Substandard use of N95 masks, sometimes combined with dry heat decontamination, lacks safety data. We evaluated the impact of these practices on the fitness of N95 masks. This is a non-human subject research conducted from July to October 2020. 155 masks were used by 12 healthcare workers during 10-hour shifts. Masks were collected at the end of the shift and if the number of donnings/doffings was less than five ({\textquoteleft}modified extended use{\textquoteright}, ME) or whenever this number reached five ({\textquoteleft}limited reuse{\textquoteright}, LR), per the recommendation of the Centers for Disease Control and Prevention. Masks that passed an Occupational Safety and Health Administration qualitative fit test underwent a cycle (30 min, 75{\textdegree}C) of dry heat decontamination. After use, 84\% (95\% CI 77\% to 90\%) of the masks fit the users, 85\% (95\% CI 73\% to 93\%) in ME and 83\% (95\% CI 73\% to 90\%) in LR. After dry heat, 86\% of the fitted masks (95\% CI 78\% to 91\%) still fit, 93\% (95\% CI 80\% to 98\%) in ME and 82\% (95\% CI 70\% to 89\%) in LR. If a fit test was not done before decontamination, 72\% (95\% CI 64\% to 79\%) of the masks would fit, 79\% (95\% CI 66\% to 88\%) in ME and 68\% (95\% CI 57\% to 77\%) in LR. Common substandard use preserves fitness of N95 masks up to 85\%. One cycle of dry heat decontamination preserves fitness of N95 masks up to 93\% when donned/doffed less than five times and fitness is ensured before decontamination. If a fit test is not performed beforehand, dry heat decontamination cannot preserve the fitness of used N95 masks above 80\%.All data relevant to the study are included in the article or uploaded as supplemental information. All data were de-identified. Data storage and processing were done using Excel documents and saved in a secure folder in Columbia Basin Health Association company folders, with access only granted to MZ and JA.}, issn = {1081-5589}, URL = {http://hw-f5-jim.highwire.org/content/70/1/99}, eprint = {http://hw-f5-jim.highwire.org/content/70/1/99.full.pdf}, journal = {Journal of Investigative Medicine} }