Evaluation of Exhaled Carbon Monoxide Levels in Individuals Exposed to Passive Tobacco Smoke in Indoor and Outdoor Environments: How Far Can We Getaway Under the Same Roof?

Introduction: Besides direct exposure, indirect contact with tobacco smoke significantly contributes to numerous health issues. Unfortunately, people are unaware that the precautions taken in closed environments are inadequate to deal with this issue. We conducted this study to assess carbon monoxide (CO) levels of people exposed to tobacco smoke indoors and outdoors. Methods: Our study between May and June 2023 included individuals exposed to tobacco smoke indoors (n=100) and outdoors (n=100). Our control group included 100 people who had never been exposed to healthy tobacco smoke and agreed to participate in our research. The amount of CO exhaled was measured by observing how long people were in contact with tobacco smoke and how close they were to it. Questionnaires were asked of the study participants about the harms and awareness of tobacco smoke exposure. Results: Exhaled CO levels were 1.46 ± 0.1 ppm in people exposed to tobacco smoke indoors, 1.1± 0.03 ppm in people exposed to smoke outside, and 1.1± 0.02 ppm in the control group. The statistical analysis revealed that individuals exposed to tobacco smoke in the indoor environment had significantly higher exhaled CO levels than those in the outdoor and the control groups (p=0.006). In the correlation analysis of time and distance in the indoor environment with the exhaled CO level, there was no statistically significant difference between time and space (r= -0.168, p=0.09, r=0.09, p=0.37, respectively). While less than half of both groups were aware of second-hand tobacco smoke, individuals exposed to tobacco smoke in the outdoor environment were more familiar (p<0.001). Conclusion: Despite the precautions, indoor tobacco smoke exposure is severe because of second- and third-hand smoke. Raising individual awareness and enhancing the steps should be our top concern to prevent future health problems.