Table 1.

Risk factors related to the host and the environment that affects incidence of childhood clinical pneumonia in the community

Definite	Malnutrition Low-birth-weight Non-exclusive breastfeeding (during the first 4 months of life) Lack of measles immunization (within the first 12 months of life) Indoor air pollution Crowding
Likely	Parental smoking Zinc deficiency Mother's experience as a caregiverConcomitant diseases (e.g. diarrhoea, heart disease, asthma)
Possible	Mother's education Day-care attendance Rainfall (humidity) High altitude (cold air) Vitamin A deficiency Birth order Outdoor air pollution

Reproduced with permission from Rudan, I. Epidemiology and etiology of childhood pneumonia. Bull World Health Organ.