Demographic characteristics and household conditions of the study participants (n=3424)
| Variable | Total | Percentage |
|---|---|---|
| Age (years) | ||
| 12 | 111 | 3.2 |
| 13 | 1582 | 46.2 |
| 14 | 1731 | 50.6 |
| Sex of child | ||
| Female | 1790 | 52.3 |
| Male | 1634 | 47.7 |
| Residential area | ||
| Kempton Park | 1117 | 32.6 |
| Tembisa | 2301 | 67.2 |
| Missing | 6 | 0.2 |
| Period lived in the residential area | ||
| <6 months | 253 | 7.4 |
| 6−2 months | 216 | 6.3 |
| 1−2 years | 346 | 10.1 |
| ≥3 years | 2609 | 76.2 |
| Born in the areas of Tembisa and Kempton Park | ||
| Yes | 1812 | 52.9 |
| No | 1609 | 47.0 |
| Missing | 3 | 0.1 |
| Type of house | ||
| Brick | 2938 | 85.8 |
| Mud | 45 | 1.3 |
| Corrugated iron | 184 | 5.5 |
| Combination | 126 | 3.7 |
| Missing | 126 | 3.7 |
| ETS exposure at residence in the past 30 days | ||
| Yes | 1452 | 42 |
| No | 1460 | 43 |
| Missing | 512 | 15 |
| ETS exposure at school in the past 30 days | ||
| Yes | 1177 | 34.4 |
| No | 1452 | 42.4 |
| Missing | 755 | 23.2 |
| Residential cooking fuel type most frequently used | ||
| Electricity | 2995 | 87.5 |
| Gas | 179 | 5.2 |
| Paraffin | 200 | 5.8 |
| Open fires (wood, coal) | 30 | 0.9 |
| Missing | 20 | 0.6 |
| Residential heating fuel type most frequently used | ||
| Electricity | 2041 | 59.6 |
| Gas | 426 | 12.4 |
| Paraffin | 631 | 18.4 |
| Open fires (wood, coal) | 270 | 7.9 |
| Missing | 56 | 1.64 |
| Mode of transport to school | ||
| Walk | 1728 | 50.5 |
| Informal taxi/Bus | 708 | 20.1 |
| Car | 683 | 20. |
| Combination car and informal taxi | 201 | 5.9 |
| Train | 100 | 2.9 |
| Missing | 4 | 0.1 |
| Frequency of trucks passing near homes on weekdays | ||
| Never | 563 | 16.4 |
| Seldom | 1033 | 30.2 |
| Frequently through the day | 580 | 16.9 |
| Almost every day | 1212 | 35.4 |
| Missing | 36 | 1.1 |
ETS, environmental tobacco smoke.