ding dong tse, excuse my poor Chinese, I got mixed up these words. Yes, it might be a hypoxic condition. Like when a person inhales a large amount of carbon monoxide. First starts to yawn then comes the headache then faint out. So did you feel dizzy?
Good to hear that you didn't have any dizziness. They should have better circulation inside the room and at least have some windows opened. Breathing in others carbon dioxide?!?.......YUCKY YUCKY!!!!!!!