Table 3. Effects of anthropometric, socioeconomic, parental and household factors on children’s lung function in Period I and Period II, respectively. The effect estimates for continuous variables are changes in lung function indexes per unit change in the variable and those for categorical variables are differences from the reference group.
| Variables | FVC (mL) | FEV1 (mL) | PEF (mL/s) | FEF25–75 (mL/s) | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Period I | Period II | Period I | Period II | Period I | Period II | Period I | Period II | ||||
| Age (year) | 6.3 | 21.6 | 38.5** | 10.5 | −323.3** | 24.2 | 150.8** | 3.6 | |||
| Height (cm) | 28.6** | 10.5* | 22.3** | 13.9** | 97.7** | 26.5* | 14.1** | 22.1** | |||
| Weight (kg) | 16.7** | 13.3** | 7.8** | 10.3** | −4.5 | 24.2* | −1.4 | 12.0 | |||
| BMI (kg/m2) | 64.0** | 42.8** | 56.1** | 38.5** | 155.4** | 89.0** | 22.1* | 53.1** | |||
| Sex (ref: male) | −99.7** | −16.6 | −90.6** | −5.8 | −154.4 | −111.1 | −91.1** | 70.6 | |||
| District (ref: urban) | 14.9 | −156.6** | 3.3 | −85.2 | −1,155.9** | 11.0 | 47.3 | 81.7 | |||
| Breast feeding (ref: no) | −16.7 | 44.5 | −14.8 | 55.7 | −189.3 | 121.0 | −50.1 | 101.7 | |||
| Father smoking (ref: no) | 44.5 | 3.1 | 32.1 | 12.0 | 38.9 | −31.8 | 86.9 | −38.3 | |||
| Mother smoking (ref: no) | −21.0 | – | −138.5 | – | −221.2 | – | −405.6 | – | |||
| Sleep in own room (ref: yes) | −38.9 | −90.0 | −33.4 | −84.3 | −267.0 | −16.3 | −36.7 | −108.5 | |||
| Sleep in own bed (ref: yes) | 32.6 | 58.7 | 15.1 | 57.1 | 15.4 | −20.0 | 14.0 | 37.6 | |||
| Household coal use (ref: no) | 13.7 | −41.6 | −13.3 | −7.9 | 236.2 | 342.4 | −35.6 | 392.3 | |||
| Ventilation use when cooking (ref: no) | −10.8 | 279.8 | 22.6 | 169.4 | 87.0 | 297.6 | 57.1 | −12.3 | |||
| Enclosed kitchen (ref: no) | −55.3** | −36.5 | −36.9* | −20.0 | 72.0 | 19.3 | −18.2 | 12.5 | |||
| Father being white collar (ref: blue collar) | 32.5 | −66.8 | 30.1 | −49.1 | −224.9 | 199.8 | 49.3 | 232.1 | |||
| Father without stable income (ref: blue collar) | 55.1 | −192.1* | 1.8 | −171.8* | −200.7 | −236.9 | 80.4 | −88.4 | |||
| Mother being white collar (ref: blue collar) | −36.0 | 113.2 | −6.2 | 90.2 | −9.7 | 27.0 | 36.6 | 6.4 | |||
| Mother without stable income (ref: blue collar) | 61.8 | −8.9 | 60.5 | −26.0 | 273.1 | −21.6 | 33.8 | 82.0 | |||
| Paternal education (ref: < college) | −6.8 | 43.1 | −32.6 | 53.1 | 85.9 | 163.7 | −126.7 | 104.1 | |||
| Maternal education (ref: < college) | 29.3 | 152.4* | 68.3 | 121.7* | 236.3 | 204.8 | 97.8 | 109.6 | |||
| Paternal asthma (ref: no) | 59.5 | – | 86.9 | – | 18.4 | – | 6.6 | – | |||
| Maternal asthma (ref: no) | −18.0 | – | −50.1 | – | −28.1 | – | −94.7 | – | |||
| Paternal bronchitis (ref: no) | 73.8 | 84.8 | 25.4 | 56.4 | −223.1 | −249.2 | −51.8 | 51.2 | |||
| Maternal bronchitis (ref: no) | 15.7 | −66.2 | 44.5 | −41.8 | −112.8 | 364.6 | 77.6 | 285.6 | |||
| Home renovation (ref: no) | NA | −66.0 | NA | −61.3 | NA | −128.3 | NA | −55.1 | |||
| Presence of pets (ref: no) | NA | 34.1 | NA | 9.5 | NA | −153.3 | NA | −43.6 | |||
| Presence of mold (ref: no) | NA | 77.0 | NA | 89.5 | NA | 131.3 | NA | 191.9 | |||
| Mosquito coil use (ref: no) | NA | 2.0 | NA | −7.9 | NA | −58.0 | NA | 68.2 | |||
| Air freshener use (ref: no) | NA | 55.6 | NA | 67.7 | NA | −35.0 | NA | 28.1 | |||
| Whether preterm birth (ref: no) | NA | −75.1 | NA | −110.9 | NA | −166.4 | NA | −142.7 | |||
| Air purifier use (ref: no) | NA | −57.6 | NA | −45.1 | NA | −266.1 | NA | −179.0 | |||
–, no data, since the prevalence rate in the period was too low. *, P<0.05; **, P<0.01. NA, not available; FVC, forced vital capacity; FEV1, forced expiratory volume in the first second; PEF, peak expiratory flow; FEF25–75, forced expiratory flow at 25% and 75% of the pulmonary volume.