Ok my husband chews tobacco, behind my back and he knows that I hate it!?

What are some ways to get him to quit, without being naggy about it? He claims that he doesn't chew "anymore" I don't believe him at all. I find all the little brown resiude everywhere, by the computer, in the bathroom. I have asked him several times, "IF you are gonna chew, chew outside and don't lie and tell me that you aren't because I know that you are." Please help!