Green means stop (At least at this restaurant)

No smoking sign at A&W

First of all, my apologies for the quality of the photograph. Apart from the increasingly questionable quality of photos from my phone, it is a blow up of a snippet of a photograph that I took over the weekend. When you are taking photos on the sly, you often don't get a chance to get things set up properly.

I saw this sign in an A&W I was in on Friday night. I think that this sign is telling me that smoking is not permitted. But, if that is the case why are the circle and line in green. That is the colour that tells me that something is permitted. But the line through the middle of the circle tells me that it is not permitted.

I didn't see anyone smoking, but I'm sure that I'm not the only one who is confused.