Researchers from the Korean National Institute of Environmental Research found that thirdhand smoke exposure in nonsmokers varied with occupation and housing type. These results suggest that Korea’s existing indoor smoking bans may not offer sufficient protection from toxic thirdhand smoke and point to the importance and challenges of distinguishing between second- and thirdhand smoke exposure.

By Leta Dickinson

August 11, 2021

Previous studies of the Korean population have found that despite indoor smoking bans in most public places, secondhand smoke exposure to tobacco is common. One recent study found that 88% of nonsmoking Korean residents had traces of cotinine, a marker of tobacco exposure, in their urine.

A team of researchers from the National Institute of Environmental Research analyzed samples collected through the Korean National Environmental Health Survey, combined with a few self-reported questions about smoking status, to determine how thirdhand smoke exposure might be affecting the population. They found that of the 2,500 nonsmoking survey respondents, cotinine was detected in nearly 94% of nonsmokers who reported living in smokefree homes. Among these respondents, cotinine levels were higher in those who lived in homes with less ventilation and spent more time at home. Employment was also associated with higher cotinine levels.

The authors note as a limitation that the study relied on self-reported smoking status.  That is smoking and smokefree homes were determined based solely on participant responses to survey questions). The study authors also acknowledge possible errors participants could have made in distinguishing between second- and thirdhand smoke: “The nonsmoking respondents in smoke-free homes, defined by questions, might have resided with occasional smokers in their homes. The present study did not take into account potential secondhand smoke from workplaces because the questionnaires did not ask. These unmeasured factors might have over- or underestimated urinary cotinine levels in nonsmoking adults.”

Nonetheless, this study makes an important contribution to understanding how widespread second- and thirdhand tobacco smoke exposure are and draw attention to the need for stricter policies worldwide to ensure equal access to clean air, regardless of a person’s occupation or housing situation.

Click here to read the research study.