“…The following factors other than tobacco use affecting the occurrence of outcomes that were used in past crosssectional studies investigating the relationship of e-cigarette or HTP use to the occurrence of outcomes (COPD, 12,[16][17][18][19][20][21][22] asthma, 12,16,18,20,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] wheezing, 13,32,[39][40][41][42][43] breath shortness/cough/phlegm, 32,33,41,42 lung function abnormality 44 ) and cohort study 45 investigating the relationship between smoking and COPD were used as adjustment factors in this study: age, sex, BMI, resident area population size, education level, household income, whether employed or unemployed, lifestyle habits (frequency of exercise, frequency of alcohol drinking, level of stress), whether historical or concurrent diseases were present (diabetes, lipid abnormality, hypertension, stroke, allergic dermatitis/rhinitis, angina pectoris, coronary heart diseases (CHD)). Information about passive smoking was not obtained in this study, because no statistical effect from passive smoking was observed 16,39 in past cross-sectiona...…”