Decrease in the urine cotinine concentrations of Korean non-smokers between 2009 and 2011 following implementation of stricter smoking regulations.

This study aimed to determine if there was an association between the implementation of smoking regulation policies and the urine cotinine concentrations of Korean non-smokers. The subjects of this study were 4612 non-smoking Korean citizens (aged 19 or older) selected from the first stage of the Korean National Environmental Health Survey conducted by the National Institute of Environmental Research from 2009 to 2011. Cotinine concentrations in urine were measured by GC-MS (limit of detection: 0.