To take action against my landlord?

[Smokeshame]

We live in a badly converted house turned into flats. Two houses next to each other, all flats, all owned by the same landlord.
The flats are non smoking, you have to smoke outside. Everyone who smokes does.

Except new neighbour who is smoking heavily and smoking what smells like weed too.

Locals have commented about the smell of weed, people visiting have commented about the smoke and smell (especially in an enclosed unventilated hall)

Our flat stinks of smoke when they are smoking and we come back to weed stinking the whole flat out at the weekend.

I'm at the asthma nurse this week with my daughter because her asthma is much worse.

The landlord is aware and has done nothing.

Help!

Have you spoken to Shelter for advice? Or to the council's housing department? You need to be clear which rules your shoddy landlord is breaking.
Def speak to fire safety. It's worrying thst smoke can so easily find its way into your flat.
The weed thing is a bit of a red herring in terms of the landlord - that's a police matter.