Smoking Rules?

You are a supervisor in a warehousing operation. You recently instituted a “No Smoking” policy in the facility. All employees were notified of the policy change. It was not well-received. As you walk down aisle B in the warehouse, you see a cloud of smoke and then see Chris running to aisle A. You need to talk to Chris.

1) Does this rule have business justification?

2) Can this rule be enforced? How?

3) As an HR manager, how will you address Chris? 

4) What are potential problems if you address Chris? What are some issues that can arise if you don't?