We have the exact same problem and also live in Qld. I know when my neighbour gets home from work because the first thing he does is have a smoke. We live in a townhouse and whilst it is no smoking on common property, you can't stop them smoking in their courtyard. They're renters so I'm hoping that they won't renew the lease when it comes up next.
All we can do is close our sliding door out to the courtyard and put the fan up or the aircon on.I'm anal about exposing DS to secondhand smoke too as I've also heard that it's worse than smoking first hand.
It's a good thing that were not outdoor people because then it would bug me more.
They've been away for Xmas and it has been heavenly. Really not looking forward to them coming home.