First of all 1) do u smoke? 2) do any one in your house hold some? 3) can u smell it all the time or different parts of the day? 4) if your worried go and speak to the doctor and tell them about it. if u dont smoke not even your family or what ever then tell the doctor that as well. DONT FORGET THOU THAT IF U GO TO THE PUB ALOT OR DOWN TOWN ECT THEN THIS COULD BE THE COURSE OF IT.