Effect of N95 face masks on cardiopulmonary stress

Editor's Note

This Chinese study finds that wearing N95 face masks for 14 hours significantly affects physiological, biochemical, and perception parameters. The effect was primarily caused by increased respiratory resistance and subsequent decreased blood oxygen and pH.

This randomized clinical trial included 30 healthy participants between March 7 and August 1, 2022, and was conducted in a metabolic chamber to strictly control daily calorie intake and physical activity levels. Participants were randomly assigned to receive exercise interventions with and without masks for 14 hours, during which thy exercised for 30 minutes in the morning and afternoon.

Wearing the N95 masks resulted in:

• reduced respiration rate and oxygen saturation by pulse oximetry within 1 hour and elevated heart rate 2 hours later until the mask came off at 10 pm after 14 hours
• increased cardiopulmonary stress, as heart rate and blood pressure increased and respiration rate and oxygen saturation decreased, during light-intensity exercise at 11 am
• elevated energy expenditure and fat oxidation at 11 am
• decreased venous blood pH and arterial pH after wearing the mask for 14 hours
• increased metanephrine and normetanephrine levels
• increased overall discomfort while wearing the N95 mask.

Although healthy individuals can compensate for cardiopulmonary overload, the elderly, children, and those with cardiopulmonary diseases may experience compromised compensation, the researchers say.