Table 2. Characteristics of the study participants and indoor exposure.
| Variables | Mean ± SD/% |
|---|---|
| Questionnaire derived data (N=2,306) | |
| Subject characteristic | |
| Age, years | 9.83±0.04 |
| Maternal education | |
| Junior high school degree or below | 18.46% |
| High school | 31.29% |
| College degree | 28.26% |
| Bachelor degree | 19.10% |
| Master degree or above | 2.89% |
| Maternal asthma | 0.67% |
| Paternal asthma | 0.90% |
| Breastfeeding duration | |
| More than six months | 37.59% |
| Maternal smoking during pregnancy | 0.45% |
| Indoor exposure | |
| ETS | 44.83% |
| Dampness and molds | 25.69% |
| Incense burning | 41.66% |
| Open kitchen | 37.07% |
| Decoration | 15.70% |
| High cooking frequency | 89.50% |
| Pets | 17.08% |
| Air conditioner use | 89.60% |
| No kitchen ventilation | 14.56% |
| Non-clean fuels | 94.09% |
| Air freshener | 7.14% |
| Higher CRIP | 15.29% |
| Respiratory diseases and symptoms | |
| Cough with a cold | 42.42% |
| Cough without a cold | 4.92% |
| Nightly a cough | 22.48% |
| Phlegm with a cold | 13.83% |
| Phlegm without a cold | 2.14% |
| Wheeze last year | 24.63% |
| Wheeze with a cold | 6.82% |
| Wheeze without a cold | 1.43% |
| Daytime and nightly wheeze | 1.49% |
| Wheeze while sleeping | 48.18% |
| Wheeze while speaking | 20.86% |
| Ever asthma | 2.85% |
| Recent asthma | 1.07% |
| Recent bronchitis | 14.95% |
| Recent pneumonia | 1.07% |
| Ever allergy | 9.66% |
| Recent allergy | 4.37% |
| Recent allergic rhinitis | 15.54% |
| Lung function data (N=987) | |
| Subject characteristic | |
| Age, years | 9.86±0.05 |
| Height, cm | 138.53±0.34 |
| Weight, kg | 33.24±0.32 |
| Sex (girl) | 47.92% |
| Lung function | |
| FVC, L | 1.68 (1.65, 1.72) |
| FEV1, L | 1.57 (1.55, 1.60) |
| PEF, L | 2.95 (2.90, 3.01) |
| FEF25%, L/S | 2.80 (2.74, 2.85) |
| FEF25–75%, L/S | 2.22 (2.18, 2.26) |
| FEF75%, L/S | 1.49 (1.46, 1.52) |
| VC, L | 1.91 (1.87, 1.96) |
| MVV, L | 46.88 (46.00, 47.80) |
| Higher CRIP | 13.24% |
Spirometric indices, geometric mean (95% CI); maternal asthma or paternal asthma, maternal asthma or paternal report of asthma ever diagnosed by a physician. CRIP, the cumulative risk of indoor pollution. ETS, environmental tobacco smoke; CRIP, cumulative risk of indoor pollution; FVC, forced vital capacity; FEV1, forced expiratory volume in the first second; FEF25%, forced expiratory flow at 25% of expired volume; FEF25–75%, forced expiratory flow between 25% and 75% of expired volume; FEF75%, forced expiratory flow at 75% of expired volume; VC, vital capacity; MVV, maximum voluntary ventilation.