This must be old data, because Maryland's smoking ban is even more restrictive than all the surrounding states and even extends to private clubs such as American Legion Posts, Moose and Elks' Lodges, etc.
The General Assembly this session is considering a law that would fine you $100(?) for smoking in your own car if there was a minor on board ...
2009 so only a few years old...
http://mercatus.org/sites/default/files/publication/Freedom_in_the_50_States.pdf