Exposure to polluted environments is associated with more than one in four deaths among children younger than 5, according to two World Health Organisation reports published today.

Worldwide, 1.7 million children's deaths are attributable to environmental hazards, such as exposure to contaminated water, indoor and outdoor pollution, and other unsanitary conditions, the reports found.

Weaker immune systems make children's health more vulnerable to harmful effects of polluted environments, the report says.

Some of the most common causes of death among children, such as malaria, diarrhea and pneumonia, can be prevented by implementing ways known to reduce environmental risks and exposure to these risks, the first report shows. About one quarter of all children's deaths and diseases in 2012 could have been prevented by reducing environmental risks.

Exposure to polluted environments is also dangerous during pregnancy because it increases the chances of premature birth. Infants and preschool children exposed to indoor and outdoor pollution are at a higher risk of contracting pneumonia and chronic respiratory diseases. The likelihood of cardiovascular diseases, cancer and stroke also significantly increases with exposure to polluted environments.

The second report quantifies the problem by providing the number of children who died because of exposure to polluted environments.

According to the report, every year:

- 570,000 children under 5 years die from respiratory infections, such as pneumonia, attributable to indoor and outdoor air pollution and second-hand smoke - smoke that is released by burning tobacco products, such as cigarettes.

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