No Smoking
The prohibition of smoking in certain areas is a regulation designed to reduce the negative externalities suffered by non-smokers when they are around smokers.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"All sizes | No smoking within 5 meters | Flickr - Photo Sharing!."
http://www.flickr.com/photos/hendry/7137645351/sizes/o/in/photostream/
Flickr
CC BY.