Tenant smoking in unit?

[Thomas Porter]

Hey guys, I am brand new at being a landlord. Just moved my first tenant in last week. To give some background my wife and I recently purchased a duplex and we are living in one unit and renting out the other. I have a strict no smoking policy in my lease and she had to be a non smoker for me to even consider her as a tenant. We have a shared foyer and it has started to smell like smoke/marijuana since the tenant moved in. I am thinking/hoping that it is just because she has some friends that smoke and the smell is being carried in on their clothes. I am wondering if you have any advice on how to find out if the tenant and/or her guests are smoking in the unit?