Validation of Biomarkers of Exposure and Host Response

Inclusion Criteria: * Subjects must be 19 years of age or older * Have a stable smoking habit greater than three months * Have smoked for at least 5 pack years * Be willing to make a serious quit attempt and be willing to use nicotine replacement therapy * Be able to give informed consent Exclusion Criteria: * regular use of anti-inflammatory medication; presence of any inflammatory \*disease of the respiratory tract including moderate or worse COPD (FEV1 \< 80% predicted and FEV1/FVC ratio \< 0.7) or PFT criteria for asthma (improvement in FEV1\>12% of predicted and \>200ml). * Subjects with normal lung function who meet criteria for diagnosis of chronic bronchitis will be excluded. * Subjects with stable medical conditions, excluding inflammatory lung disease, will be permitted to participate, providing anti-inflammatory therapies are not used regularly and providing there has been no change in their clinical status in the two months prior to beginning the study.