Relationship between binary SHS exposure and respiratory symptoms
| SHS exposure | n | Respiratory symptoms (%) | Unadjusted OR (95% CI) | Adjusted OR (95% CI)* |
| SHS exposure in general | ||||
| No | 1101 | 106 (9.6) | 1.00 | 1.00 |
| Yes | 2474 | 371 (15.0) | 1.66 (1.32 to 2.08) | 1.72 (1.35 to 2.17) |
| SHS exposure in indoor public places | ||||
| No | 1806 | 200 (11.1) | 1.00 | 1.00 |
| Yes | 1769 | 277 (15.7) | 1.49 (1.23 to 1.81) | 1.60 (1.30 to 1.95) |
| SHS exposure in homes | ||||
| No | 2342 | 275 (11.7) | 1.00 | 1.00 |
| Yes | 1233 | 202 (16.4) | 1.47 (1.21 to 1.79) | 1.53 (1.25 to 1.87) |
| SHS exposure in indoor campuses | ||||
| No | 2763 | 338 (12.2) | 1.00 | 1.00 |
| Yes | 812 | 139 (17.1) | 1.48 (1.19 to 1.84) | 1.43 (1.14 to 1.79) |
| SHS exposure in indoor campuses from smoking teachers | ||||
| No | 2940 | 369 (12.6) | 1.00 | 1.00 |
| Yes | 635 | 108 (17.0) | 1.43 (1.13 to 1.80) | 1.34 (1.05 to 1.71) |
| SHS exposure in indoor campuses from smoking classmates | ||||
| No | 3149 | 399 (12.7) | 1.00 | 1.00 |
| Yes | 426 | 78 (18.3) | 1.54 (1.18 to 2.02) | 1.54 (1.15 to 2.06) |
| SHS exposure in outdoor campuses | ||||
| No | 2532 | 309 (12.2) | 1.00 | 1.00 |
| Yes | 1043 | 168 (16.1) | 1.38 (1.13 to 1.69) | 1.37 (1.10 to 1.69) |
| SHS exposure in outdoor campuses from smoking teachers | ||||
| No | 2917 | 362 (12.4) | 1.00 | 1.00 |
| Yes | 658 | 115 (17.5) | 1.49 (1.19 to 1.88) | 1.38 (1.09 to 1.75) |
| SHS exposure in outdoor campuses from smoking classmates | ||||
| No | 2873 | 366 (12.7) | 1.00 | 1.00 |
| Yes | 702 | 111 (15.8) | 1.29 (1.02 to 1.62) | 1.33 (1.03 to 1.71) |
*adjusted for gender (male vs female), grade (4–5 vs 1–2), only child (yes vs no) and asthma history (yes vs no).
n, number of participants; SHS, second-hand smoke.