Chronic obstructive pulmonary disease (COPD) is a condition that is characterized by airway obstruction due to inflammation. Levels of inflammatory proteins may be linked to when and to what extent COPD develops. This study will use data collected during the Tucson Epidemiological Study of Airway Obstructive Disease (TESAOD) and its 33-year follow-up to determine the relationship between inflammatory protein expression and COPD.