Objective: Our aim is to evaluate the validity of exhaled carbon monoxide (CO) and of a newly-created score as markers of Chronic Obstructive Pulmonary Disease (COPD). Materials and Methods: The CO level was measured in a derivation subsample of a cross-sectional study and linked to COPD diagnosis; its predictors were evaluated, and a scale was constructed. It was evaluated in a validation subsample and in a clinical setting. Results: Individuals with COPD had higher CO levels than healthy individuals. CO level signifi cant predictors were cigarettes per day, waterpipes per week, lower age, male gender, living close to diesel exhaust, heating home with the use of diesel, and having indoor family smokers. A score composed of CO predictors was able to signifi cantly predict COPD (Ora = 4–7.5). Conclusions: Coupled with the clinical judgment of physicians, this scale would be an excellent low-cost tool for screening COPD, in absence of spirometry.