Smoking exposure | Passive smoke exposure | Smoking status during pregnancy (4 months) | | | Living with a smoker | Living with smoker at any stage | Combined passive smoking exposure (in utero, childhood and adulthood) personal smoking in adulthood |
Personal smoking status | | | | | Persistent smoker ever smoker, and never smoker |
SC | SC (occupation and classified as: professional/managerial, unskilled nonmanual, skilled manual, unskilled manual) | SC of male head | | SC of male head | | | | Own SC | Combined social class at birth, 11 and 42 years (range 0–9), with higher scores indicating lower social class |
Asthma | Asthma | | Report of ever having asthma or bronchitis | | Ever asthma in adulthood | Childhood and adulthood reporting of asthma |
Others | Low birth weight | Birth weight <2.5 kg | | | | | | | |
Preterm birth | Gestation age <37 weeks | | | | | | | |
Pneumonia | | Ever had pneumonia | | | | | | |
Occupation exposure | | | | | | Minimal or potential occupational exposure to dust, gases and fume | |
Biomass exposure | | | | | | Paraffin or solid fuel as heating source | |