No smoking signs are generally placed inside commercial buildings and in some vehicles. Here are some useful signs that people commonly use. Take a look.
Free and Printable No Smoking Signs
The black and white signs are drawn with red caution symbols. Some signs have words and some do not have anything but the picture.
Hope the signs are all useful to you and your known people who really need them. Printing is easy, and sticking them to the wall is easier.