Adjusted odds ratios for SHS exposure and medical services use in current and never-smokers.

aAdjusting for sex, age, highest parental education, housing type, school clustering effects, mutually adjusted for SHS at home and outside home, and additionally adjusted for cigarette consumption per day and years of smoking in current smokers.bOnly students who had been exposed to SHS outside home ≤2 days/wk were included.cP for interaction between any SHS exposure in current and never-smokers.dOnly students who had been exposed to SHS at home ≤2 days/wk were included.