Table 3

Relationship between frequency of SHS exposure and respiratory symptoms

Frequency of SHS exposurenRespiratory
symptoms (%)
Unadjusted OR (95% CI)Adjusted OR (95% CI)*
SHS exposure in indoor public places
 No exposure1806200 (11.1)1.001.00
 1 to 4 days/week1242184 (14.8)1.40 (1.13 to 1.73)1.50 (1.20 to 1.86)
 5 to 7 days/week52793 (17.7)1.72 (1.32 to 2.25)1.87 (1.41 to 2.46)
Continuous SHS in indoor public places†2.06 (1.52 to 2.80)2.30 (1.67 to 3.16)
SHS exposure in homes
 No exposure2342275 (11.7)1.001.00
 1 to 4 days/week57097 (17.0)1.54 (1.20 to 1.98)1.62 (1.25 to 2.09)
 5 to 7 days/week663105 (15.8)1.41 (1.11 to 1.80)1.45 (1.13 to 1.87)
Continuous SHS in homes†1.56 (1.18 to 2.07)1.64 (1.23 to 2.20)
SHS exposure in indoor campuses
 No exposure2763338 (12.2)1.001.00
 1 to 4 days/week53981 (15.0)1.27 (0.98 to 1.65)1.24 (0.95 to 1.63)
 5 to 7 days/week27358 (21.3)1.94 (1.42 to 2.64)1.84 (1.32 to 2.56)
Continuous SHS in indoor campuses†2.19 (1.53 to 3.12)2.09 (1.42 to 3.07)
SHS exposure in indoor campuses from smoking teachers
 No exposure2940369 (12.6)1.001.00
 1 to 4 days/week41259 (14.3)1.16 (0.87 to 1.57)1.13 (0.84 to 1.53)
 5 to 7 days/week22349 (22.0)1.96 (1.40 to 2.74)1.78 (1.25 to 2.53)
Continuous SHS in indoor campuses from smoking teachers†2.27 (1.54 to 3.33)2.06 (1.37 to 3.09)
SHS exposure in indoor campuses from smoking classmates
 No exposure3149399 (12.7)1.001.00
 1 to 4 days/week27145 (16.6)1.37 (0.98 to 1.92)1.38 (0.97 to 1.97)
 5 to 7 days/week15533 (21.3)1.86 (1.25 to 2.78)1.84 (1.20 to 2.82)
Continuous SHS in indoor campuses from smoking classmates†2.04 (1.30 to 3.20)2.00 (1.22 to 3.26)
SHS exposure in outdoor campuses
 No exposure2532309 (12.2)1.001.00
 1 to 4 days/week704105 (14.9)1.26 (0.99 to 1.60)1.28 (1.01 to 1.64)
 5 to 7 days/week33963 (18.6)1.64 (1.22 to 2.21)1.56 (1.13 to 2.15)
Continuous SHS exposure in outdoor campuses†1.79 (1.27 to 2.51)1.70 (1.18 to 2.47)
SHS exposure in outdoor campuses from smoking teachers
 No exposure2917362 (12.4)1.001.00
 1 to 4 days/week45671 (15.6)1.30 (0.99 to 1.72)1.24 (0.94 to 1.64)
 5 to 7 days/week20244 (21.8)1.97 (1.38 to 2.79)1.74 (1.20 to 2.50)
Continuous SHS in outdoor campuses from smoking teachers†2.53 (1.71 to 3.74)2.20 (1.45 to 3.33)
SHS exposure in outdoor campuses from smoking classmates
 No exposure2873366 (12.7)1.001.00
 1 to 4 days/week45162 (13.8)1.09 (0.82 to 1.46)1.16 (0.86 to 1.57)
 5 to 7 days/week25149 (19.5)1.66 (1.19 to 2.31)1.66 (1.16 to 2.39)
Continuous SHS in outdoor campuses from smoking classmates†1.55 (1.05 to 2.30)1.58 (1.03 to 2.42)
  • *Adjusted for gender (male vs female), grade (4–5 vs 1–2), only child (yes vs no) and asthma history (yes vs no).

  • †Use logarithmic exposure (days/week) in the model.

  • n, number of participants; SHS, second-hand smoke.