Table 1 Characteristics of the study population of 4530 students at 22 schools in greater Wuhan, China
| Characteristic | % |
|---|---|
| Subjects | |
| Age (mean, SD) in years | 13.6, 0.7 |
| Gender | |
|
Male Female |
52.5 47.5 |
| Respiratory symptoms | |
| Wheezing with colds | 19.4 |
| Wheezing without colds | 7.1 |
| Bringing up phlegm with colds | 16.7 |
| Bringing up phlegm without colds | 5.7 |
| Coughing with colds | 24.7 |
| Coughing without colds | 4.5 |
| Exposures | |
| Smokers in child's household | |
|
No smokers 1 smoker 2+ smokers Father smokes Mother smokes Personal smoking by students |
26.8 62.3 10.9 69.1 3.6 0.6 |
| Exposure to coal burning | |
|
No coal use Coal used only for heating Coal used only for cooking Coal used for cooking and heating |
54.2 8.8 25.9 11.1 |