Surgical masks and filtering facepiece class 2 respirators (FFP2) have no major physiological effects at rest and during moderate exercise at 3000 m altitude. A randomised controlled trial.

Although mask use was associated with higher rates of dyspnoea, it had no clinically relevant impact on gas exchange at 3000 m at rest and during moderate exercise, and no detectable effect on resting cognitive performance. Wearing a surgical mask or an FFP2 can be considered safe for healthy people living, working, or spending their leisure time in mountains, high-altitude cities, or other hypobaric environments (e.g. aircrafts) up to an altitude of 3000 m.