This study aims to evaluate the effect of smokers’ nicotine addiction levels and physical activity capacities (aerobic capacities) on exhaled carbon monoxide (CO) measurement values in respiratory air.

This study is a cross-sectional epidemiological descriptive type study. About 146 smokers, aged 18 and above, who applied to Hacettepe University Family Medicine outpatient clinics between March and May 2023 were included in the study. The Fagerström Test for Nicotine Dependence (FTND) and 6-minute walk test (6-MWT) were performed to the participants, and the relationship of the data with exhaled CO level was examined.

In the data we obtained, it was observed that the addiction score evaluated by the FTND had a positive, moderately statistically significant effect on the CO level (r = 0.483 p < 0.001). Although the percentage of aerobic capacity (physical activity capacities) assessed by the 6-MWT appeared to have a very weak negative relationship with the exhaled CO level, it was found to be not statistically significant (r = −0.112 p = 0.177).

The data we obtained showed that smoking addiction has harmful effects such as increasing CO in the body, but there is no relationship between physical activity and the amount of exhaled CO. It has been observed that quitting smoking and complying with lifestyle change recommendations are an important necessity for a healthier life. To improve patients’ overall health outcomes, family physicians are crucial in helping patients quit smoking and encouraging lifestyle modifications. This study might have encouraged the reflection of smoking habits and thus motivated quitting.