evidence: Real-time breathomics has revealed a deeper insight into the physiometabolic side-effects of face mask wearing. Based on more recent pilot observations of cardiopulmonary parameters during exercise and rest in 12 healthy adults [11], researchers have generally recommended the continuous mask use. Within our setup, we have investigated the respiratory, haemodynamic and downstream metabolic changes in young to middle-aged and older adults for a longer period of time. Although we observed significant side-effects and good compensation/adaptation trends in healthy adults aged <60 years, those side-effects emerged profoundly towards substantial risk in subjects aged ≥60 years within 15 min. Mask-induced profound arterial oxygen decline, hypercarbia, deteriorating ventilation, compartmental vasoconstrictions and blood pressure alterations in older adults turned out to be concerning upon the general health/clinical status under prolonged use of FFP2 face masks at rest. According to the recent observations from a randomised controlled trial, COPD patients (outpatient-diagnosed and nonsevere/moderate) wearing surgical masks during a 6-min walk test tend to develop dyspnoea (without having any decrease in 6-min walk distance or O2 saturation) compared to those without masks [84]. Thus, Hirai et al. [84] have recommended surgical mask as safe for COPD patients.