Inclusion Criteria - COPD Cases:
* COPD (FEV1/FVC \< 0.7, FVC \>= LLN), GOLD Stage I/II/III (FEV1 \>= 40%)
* Current or former smoker of at least 10 pack years
Inclusion Criteria - Controls:
* Normal lung function (FEV1/FVC \>= 0.7, FEV1 and FVC \>= LLN)
* Current or former smoker of at least 10 pack years
Exclusion Criteria:
* Platelet count \< 150,000/dL or self-report of a bleeding disorder;
* Regular use of aspirin, clopidogrel or another antiplatelet medication;
* Allergy to aspirin, clopidogrel, albuterol or iodine/IV contrast;
* BMI \> 35;
* History of intracranial hemorrhage, severe GI bleed or other life-threatening bleed;
* Use of blood thinner (e.g. warfarin, lovenox or novel oral anti-coagulants);
* Continuous use of supplemental oxygen at home;
* Regular use of an NSAID;
* Daily use of oral steroids, theophylline, roflumilast, or loop diuretics;
* History of organ transplant or autoimmune disease on systemic therapy (rheumatoid arthritis, lupus);
* Use of a biologic medication with regular injections;
* Other current lung disease (interstitial lung disease, idiopathic pulmonary fibrosis, asthma);
* IV drug use within the last year;
* History of lung surgery to remove part of the lung;
* Known bullae or advanced destructive emphysema in more than 1/3 of the lungs;
* Treatment for cancer (systemic therapy or surgical/radiation within the thorax) in the last 12 months;
* Known diagnosis of pulmonary hypertension;
* Known systolic heart failure (RV or LV EF \< 40%);
* Acute or chronic renal insufficiency (estimated glomerular filtration rate \[GFR\] \<60 mL/min/1.73 m2 or self-report). GFR will be calculated using the CKD-EPI equation;
* Current or planned pregnancy in the next year;
* Regular marijuana smoking;
* Exacerbation of respiratory symptoms within the previous 6 weeks, such as that requiring hospitalization, oral prednisone or antibiotics to control symptoms, or longer and not yet returned to baseline; and
* Chest, abdominal or eye surgery, or a heart attack or stroke, within the last 3 months.
