biostudies-literatureIitani KNIBIB NIH HHSUniversity of Maryland, Baltimore CountyNational Institutes of HealthJapan Society for the Promotion of Science50-56https://www.ebi.ac.uk/biostudies/studies/S-EPMC8550888biostudies-literatureUnknown98Medical professionals have complained of extreme discomfort and fatigue from continuous wearing of N95 respirators (N95) overlaid with surgical masks (SM) and face shields (FS) during COVID-19 pandemic. However, there are no reports on the effect of face coverings on transdermal CO₂ (TrCO₂) levels (a measure of blood CO₂) during moderate activity. In this study, real-time monitoring of TrCO₂, heart rate and skin surface temperature was conducted for six subjects aged 20-59 years with and without wearing personal protective equipment (PPE). We initially studied the effect of wearing PPE (N95+SM+FS) at rest. Then, the effect of moderate stepping/walking activity (120 steps per minute for 60 min) while wearing PPE was evaluated. In addition, we inveMedical engineering & physicsWhat do masks mask? A study on transdermal CO₂ monitoring.PMC8550888JP19J01649U01 EB0219521U01EB021952-01Ramamurthy SSRao SIitani KRao GGe XTyson JfalseWhat do masks mask? A study on transdermal CO₂ monitoring.Medical professionals have complained of extreme discomfort and fatigue from continuous wearing of N95 respirators (N95) overlaid with surgical masks (SM) and face shields (FS) during COVID-19 pandemic. However, there are no reports on the effect of face coverings on transdermal CO₂ (TrCO₂) levels (a measure of blood CO₂) during moderate activity. In this study, real-time monitoring of TrCO₂, heart rate and skin surface temperature was conducted for six subjects aged 20-59 years with and without wearing personal protective equipment (PPE). We initially studied the effect of wearing PPE (N95+SM+FS) at rest. Then, the effect of moderate stepping/walking activity (120 steps per minute for 60 min) while wearing PPE was evaluated. In addition, we inve2021-01-01T00:00:00Z2021 Dec2026-05-08T18:36:51.682Z2022-02-11T13:25:02.97ZS-EPMC85508883484803810.1016/j.medengphy.2021.10.013