Table 3.
Relationship between frequency of SHS exposure and respiratory symptoms
| Frequency of SHS exposure | n | Respiratory symptoms (%) |
Unadjusted OR (95% CI) | Adjusted OR (95% CI)* |
| SHS exposure in indoor public places | ||||
| No exposure | 1806 | 200 (11.1) | 1.00 | 1.00 |
| 1 to 4 days/week | 1242 | 184 (14.8) | 1.40 (1.13 to 1.73) | 1.50 (1.20 to 1.86) |
| 5 to 7 days/week | 527 | 93 (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 exposure | 2342 | 275 (11.7) | 1.00 | 1.00 |
| 1 to 4 days/week | 570 | 97 (17.0) | 1.54 (1.20 to 1.98) | 1.62 (1.25 to 2.09) |
| 5 to 7 days/week | 663 | 105 (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 exposure | 2763 | 338 (12.2) | 1.00 | 1.00 |
| 1 to 4 days/week | 539 | 81 (15.0) | 1.27 (0.98 to 1.65) | 1.24 (0.95 to 1.63) |
| 5 to 7 days/week | 273 | 58 (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 exposure | 2940 | 369 (12.6) | 1.00 | 1.00 |
| 1 to 4 days/week | 412 | 59 (14.3) | 1.16 (0.87 to 1.57) | 1.13 (0.84 to 1.53) |
| 5 to 7 days/week | 223 | 49 (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 exposure | 3149 | 399 (12.7) | 1.00 | 1.00 |
| 1 to 4 days/week | 271 | 45 (16.6) | 1.37 (0.98 to 1.92) | 1.38 (0.97 to 1.97) |
| 5 to 7 days/week | 155 | 33 (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 exposure | 2532 | 309 (12.2) | 1.00 | 1.00 |
| 1 to 4 days/week | 704 | 105 (14.9) | 1.26 (0.99 to 1.60) | 1.28 (1.01 to 1.64) |
| 5 to 7 days/week | 339 | 63 (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 exposure | 2917 | 362 (12.4) | 1.00 | 1.00 |
| 1 to 4 days/week | 456 | 71 (15.6) | 1.30 (0.99 to 1.72) | 1.24 (0.94 to 1.64) |
| 5 to 7 days/week | 202 | 44 (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 exposure | 2873 | 366 (12.7) | 1.00 | 1.00 |
| 1 to 4 days/week | 451 | 62 (13.8) | 1.09 (0.82 to 1.46) | 1.16 (0.86 to 1.57) |
| 5 to 7 days/week | 251 | 49 (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.