| 摘要 |
PROBLEM TO BE SOLVED: To provide low oxygen content air suitable for encouraging a health and promoting the prevention and medical care of diseases for a relatively long time. SOLUTION: A communication tube 5 is connected at its end to a through- hole 3 provided in a dovetail mask 1. A balloon respiratory gas storage portion 7 is connected to the other end of the communication tube 5. The mask 1 has an outside air supply port 9 passed therethrough for supplying outside air during respiration. When a mouth and a nose are covered to be blocked with the mask 1 in respiration, the concentration of oxygen in gas staying in the respiratory gas storage portion 7 is slowly reduced while receiving outside air supplied from the outside air supply hole 9.
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