MIHAELA TRENCHEA, AGRIPINA RASCU, MARINA RUXANDRA OTELEA, EDWIN SEVER BECHIR, ELENA DANTES, DOINA ECATERINA TOFOLEAN, ILEANA ION, OANA CRISTINA ARGHIR INCREASED EXHALATED CARBON MONOXIDE, SMOKING AND OBSTRUCTIVE SLEEP APNEA Although exhaled carbon monoxide (CO) is studied from decades, a few studies are about its levels in smokers with obstructive sleep apnea (OSA). The average level of exhaled CO (eCO) was determined in OSA smokers and found increased significantly higher than in patients with other breathing related sleep disorders. A gender significant difference in average eCO was also noticed, with higher numbers in men, in OSA patients. A threshold of the eCO ³ 6 ppm has 100% specificity and 96.3% sensitivity in detection of the active smoking habit in patients with OSA. Among OSA comorbidities, only chronic obstructive pulmonary disease (COPD) seams to influence the increased eCO levels in OSA active smokers.