CO2, gas produced by the human body, is contained in human exhalation for about 4%. In addition, CO2 is used as a raw material for food packaging or carbonated drinks and is a gas that is familiar to the human body as even separately used for medical purposes.  

The US National Institute for Occupational Safety and Health (NIOSH) and the Korean Ministry of Employment and Labor have CO2 exposure standards via official notifications. The exposure standard is defined as 'the concentration that does not adversely affect the health of almost all workers', and the exposure to CO2 of less than 15 minutes at maximum 3% satisfies this standard.  

gosleep includes 5 safety devices, keeping the concentration of the mixed gas constant and never leaks gas in any circumstances. Also, the gosleep dedicated cylinder does not raise the CO2 concentration of over 1% in a 6.6 m2 room even if the whole content is leaked.