This project will evaluate the effects of World Trade Center (WTC) exposure in WTC responders 10-13 years following the events of 9/11. Prior studies have described persistent pulmonary function abnormalities in a significant portion of responders. The investigators study seeks to examine the relationship between pulmonary function abnormalities and other markers of chronic cardiopulmonary disease and further elucidate the pathophysiologic effects of exposure to inhaled particulate matter (PM) on 9/11. This study will provide critical information regarding risk of exposure to PM, risk factors for disease and potential for improvements in diagnosis and treatment.