Chain Smoking Coworker

My coworker is a chain smoker, has been smoking since he was 14. Avoids smoking around me while I am pregnant but stinks of it when he comes in doors. Now we are sharing the same office and I cannot get away from the smell! The one time I mentioned that he has a strong smoke order and he may not be able to smell it like those around him do, he got extremely offended. He has not taken any means to respect the shared space so what can I buy to purify the air in our office? I am trying to find an alternative to over-powerful air fresheners but can’t think of anything else to get ride of the smell! Help!