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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
To what extent must the oxygen content be reduced before an explosion of methane and air is impossible?
assistant
The correct answer is  For a mixture of strictly methane and air, the oxygen content must be 12 percent or less. 
It is however, significant to note that there is a combination of combustible gases following explosions and during fires.
So the maximum allowable oxygen will vary according to variations in the combustible and inert gases.