Last year 920,000 children under the age of five died of pneumonia, making it the leading killer of people in that age group.
This figure is falling (in 2011 it was 1.2m), but it still represents 16% of all infant deaths.
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Pneumonia is a result of bacterial, viral or fungal infection of the lungs.
The hospital now deploys it routinely and the number of children who die there from pneumonia has fallen by three-quarters.
Dr Chisti and his team are about to start trials of the new ventilator in a group of hospitals in Ethiopia.
All in all, the Chisti bottle-based ventilator shows what can be achieved by stripping an idea down to its basic principles. »