<s>[INST] I am concerned about a friend who seems to zone out and almost fall asleep during a conversation. I discovered aluminum foil with a black sooty residue hidden in bathroom trash. There was an unusual odor in the room also. Can this foil be tested or does it need to be done? [/INST] Thanks for asking in Chat Doctor forum In short: Any incomplete combustion can release Carbon monoxide(CO) which can cause unconsciousness and even death. Explanation: Incomplete combustion of any material will release carbon monoxide to the atmosphere and if Carbon monoxide inhales can cause incapacitation/unconsciousness and eve death.  So, have complete ventilation in your bathroom and avoid any short circuits/burning inside the room. Hope this will help you. Please let me know. </s>