what should i do if a new neighbor is smoking while on oxygen?

he was smoking outside and i mentioned it to him about smoking while on oxygen, he shut it off but still i heard even if you shut it off it can still start fires, people in my bldg smoke but i think its even more stupid to do it while on oxygen, even if hes outside he could still start a fire,should i report him to my apt manager or to someone else and if so who? i get it that people like to smoke but hes putting everyone at risk of a fire starting, even if hes outside it can spread towards inside the bldg. i myself have never smoked and never done drugs and dont drink, i know people like to smoke but what do you do when theyre putting others in danger cause of it?