According to TransWeb, people typically develop serious and possibly irreversible brain damage after 5 to 10 minutes of not breathing. Brain cells begin to die after 1 minute without oxygen. Serious brain damage is likely within 3 minutes without breathing.
TransWeb states that after 10 minutes, a large number of brain cells have died, and it is unlikely that the person can recover. After 15 minutes have elapsed, recovery is virtually impossible.
There is one exception, according to TransWeb. If a child stops breathing and simultaneously becomes very cold, survival time is sometimes extended. Survival after more than 30 minutes has been documented.