Introduction:
COPD is linked with smoking, a habit mainly seen in Asian men. In Asian countries, a large number of nonsmoking COPD existed among women, most likely from second hand smoking.

Objectives:
To compare the harm of COPD between smokers and nonsmokers.

Methods:
A cohort of 483603 adults in Taiwan went through health surveillance program between 1994 and 2008, with health data collected including spirometry and medical and lifestyle history. A total of 32535 COPD, 6.7% of the cohort, was defined by GOLD guideline with forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio

Results:
There were twice as many nonsmoking COPD (10,112) as smoking COPD (4,654). The distribution by the 4 stages of COPD was also similar. Two thirds of nonsmoking COPD came from women with second hand smoking exposure. Adjusted HRs were similar between smoking COPD and nonsmoking COPD when they were compared with their own group. HRs for smoking COPD and nonsmoking COPD were 1.47 and 1.53 for all-cause mortality, 1.53 and 1.65 for expanded CVD, 1.10 and 1.33 for cancer, and 13.08 and 15.8 for COPD.

Conclusion(s):
There were twice as many nonsmoking COPD than smoking COPD. Most of nonsmoking COPD were women with second hand smoking. The harm of nonsmoking COPD within nonsmokers was similar to that of smoking COPD within smokers. Reduction of second hand smoke was just as important as in reduction of first hand smoke.