Kim WJ, Song JS, Park DW, Kwak HJ, Moon JY, Kim SH, Sohn JW, Yoon HJ, Shin DH, Park SS, Kim TH
BACKGROUND/AIMS: Smoking is widely acknowledged as the single most important risk factor for chronic obstructive pulmonary disease (COPD). However, the risk of COPD in nonsmokers exposed to secondhand smoke remains...