Neighbour smoking drugs in their garden causing smell

[ElonsMusk]

This is more What Would You Do.

The person who lives behind us has taken to smoking something in their garden (our gardens back onto each other) and it’s making a horrible smell. It’s definitely not cannabis, it has a more chemical smell and it’s really strong. I can’t use my garden or let the DC in it.
Do I report it? Speak to them? Leave it? I don’t know these people at all. WWYD?

ask him to consider wind direction and smoke when it won't affect you.

hopefully it is something really toxic and he will die quickly.

Ask politely to smoke it in their house. Unless they’re the type that belongs on nightmare neighbours.