How to trigger fan when cigarette smoke is detected?

My bedroom window is located such that cigarette smoke from two different neighbors tends ot find its way into my bedroom.

I find this disgusting. At the same time, I understand that they smoke right outside their own doors which to them seems reasonable. (and is)

I have bought an air purifier.

When I am trying to sleep if my room gets stinky I turn it on.

For various reasons I dont want to be running all the time.

What I would like is:

1. Sensor detects cigarette smoke 2. Start air purifier 3: 15 minutes later turn off air purifier (loop)

That would give me the added benefit of getting rid of smoke when I am sleeping.

If it sometimes triggers because it thinks it detected snmoke that is fine. If it sometimes fails to trigger on smoke is sub optimal.

How can I do this?

I am wondering if I can get a fire alarm to be hypersensitive.

However, I am thinking that hte concentration of smoke is low, making it hard to detect. As opposed to a firealarm in the toilet of an aircraft which would get near 100% of it.

Does that make the project quite impossible?