I wouldn’t grass some people up for smoking weed if I knew it would mean they would be executed. On a moral basis the guilt I’d feel at their deaths would exceed the satisfaction of no longer having to smell the weed.
I assume that is why the OP used the word should.
If the OP doesn’t want to escalate the issue to the point of human beings getting killed, then talking to his neighbours would be a better starting point.
how do you know they are not [undercover] cops or agents?
best to move or let sleeping dogs lies.
be prepared for the consequences of being the nail that sticks up
Nice wordplay. 
How funny would it be if it was a superstitious guy, witch or cult just clearing the place of evil spirits with some well cured artemisia species 
Ps. High rises here are notorious for cheapo construction. Shared exhaust is the norm. Just wait till you learn about the floor drains
What is this bullshit about death penalty for dope smoking? All you get these days is a slap on the wrist and a little education course and a year of piss testing.
You get death by bumba.
Because they haven’t been arrested by other undercover cops?
I agree the anonymous note would be the way to go. They may not even be aware that their “exhaust” is blowing around the building, and they’ll probably be keen for it to not happen just on the offchance somebody does snitch.
+1 Anonymous note however I suggest with magazine cutouts instead of handwriting. Oh no, wait a minute that would take forever with Chinese, forget that…
One great way to instill a sense of paranoia in this neighbor is when you see him/her next time ask them if they know why the police were walking around the hallways with a drug sniffing dog. You can tell them that they asked you questions about people doing drugs. Of course you know nothing.
I’d knock on their door and ask them if they smell this strange odor and ask them what it is. Tell them the smell bothers you. Remind them pot is illegal. This may be enough for them to knock it off. It’s shocking and scary when folks say a death penalty is appropriate. I know they don’t execute people for pot but the OP’s suggestion that he could turn them in and they’d receive the death penalty is creepy. And what if it’s not pot???
You mean it could be sage or marjoram?
Maybe? The OP thinks the death penalty is in order so maybe he doesn’t know what mj smells like.
The fact that the OP is attempting to use the law as his own personal hitman for what is at most, an inconvenience is shocking and appalling. Thank god the authorities dont actually use the death penalty all that often. And no. The death penalty only ‘applies’ when bringing it into the country. And it has to be egregious to even consider that.
Appalling…
As I said it’s a controversial opinion. Opinion not based on fact either.
I read the original post as saying that the OP was in a quandary in that if they reported the possible weed smokers they might get them executed. Thus the use of the word should. There’s no suggestion that the OP wants weed smokers killed - quite the opposite in fact.
As it’s now been confirmed that weed smokers don’t get killed by the State, the question is should the OP still report them?
Had a similar problem with non-illegal smells before. Blocked and covered vents, used a fan blowing other direction, moved my air cleaner machine, set up fragrant candles not burning, started using air freshener mist machine.
Happy to have that clarified for us all lol.
What they should do is put a sign up in multiple languages in the elevstor.
Smoke is being blown through the extractor. Neighbours on this floor or this floor can smell the smoke.
I would say they should smoke outside but I often get smoke blowing back in then from the balcony.
Absolutely not. Why rat on foreigners because they’re breaking a random law? If you see your neighbor (Mr Huang) banging Mrs Chen from round the corner are you gonna call the cops and report adultery?
My wife’s name is Chen. That bastard Huang is going down.