Why not have a polite word with the neighbours? They may not realise that you work during the week and have only the weekend in which to do your washing. They may be retired/semi retired and burn their non-easily recyclable garden debris when the weather conditions are right, without meaning to offend. Having said that, if your houses are in close proximity and they can clearly see over into your garden at your washing line and still go ahead with their bonfires then do your worst!