This idea of waiting in a queue suggests to me a feeling of time. Waiting in a queue can be a very slow process where you feel every second go by. This has a connotation of waiting in a queue to die from smoking. It may take months, years for the effects to be noticeable or become fatal but it is only a matter of time. The queue is almost invisible because effects of smoking are internal therefore people put them under the carpet. This gives me the idea of skeletons in the closet.