I need some No Smoking signs (whinge, whinge)

Anyone know where I can get some?
From my local council perhaps?
Newsagents?
I'll ask around. 

I'm getting rather enormously pissed off on this issue.

I have asthma type reactions to various allergies, all of them airborne pollutions of one kind or another. Pollens mostly, also mould spores, and another major trigger, cigarette smoke.
These things cause me tightness in the chest, shortness of breath and fits of coughing.
Really bad coughing. 
Coughing up a lung coughing. 
Unable to breathe and talk at the same time without coughing.
Which has been a little awkward at the checkout....

It has been really bad this year, with several trips to the doctor resulting in some fairly strong medication, which is helping, but slowly.
(Just like last year, when I thought I had bird flu)

When I'm at home, I like to open the doors and windows to get some fresh air blowing though my little home.
Sadly,  I'm unable to leave them open very long as I find the place filling with the stink of cigarettes that people nearby are smoking.
Sometimes (too often) they aren't regular cigarettes either.
Whatever it is they are smoking, the smell seems to find its way into my home through either the front or back doors and windows, or both, and I don't notice it until it is too late.
When I start coughing. 

This does not happen every day, sometimes I can leave the doors and windows open.
But only sometimes

I don't see anybody standing around outside, so can only surmise the smoke is filtering down from the upstairs balconies.

I'm thinking of putting No Smoking signs beside both windows and both doors.
Do you think that will work?
Or will it piss them off and make them smoke even more?