As pointed out by Drs. Covington and Moon, in response to our recent article, mitigating the risk of decompression sickness is of utmost importance for future missions to the Moon or Mars. This risk is proportional to the ratio R between the partial pressure of nitrogen in the tissues and the pressure of the spacesuit. For future space exploration missions, an acceptable risk of decompression sickness is reached for an R less than 1.3 to 1.4. Whereas the atmosphere inside the International Space Station is normoxic and normobaric (14.7 psi and 21% oxygen), the American spacesuit circulates pure oxygen pressurized at 4.3 psi (about 0.3 atm). As a consequence, astronauts prebreathe oxygen for 4 h to wash out nitrogen from body tissues (to reduce the partial pressure in the tissues) before depressurization, with the option to enhance denitrogenation with physical exercise.3,4  For...

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