More than 13 million deaths annually are due to preventable environmental causes that can be averted by well-targeted interventions, a WHO report has said. The report, "Preventing disease through healthy environments-towards an estimate of the environmental burden of disease" estimates that more than 33 per cent of diseases in children below five years are caused by environmental exposures. Preventing environmental risk can save as many as four million lives a year, mostly in developing countries, it adds.

The report estimates that as much as 24 per cent of global diseases are caused by environmental exposures. Nearly one third of deaths and diseases in the least developed regions are due to environmental causes.

Over 40 per cent of deaths from malaria and an estimated 94 per cent of deaths from diarrhoeal diseases, two of the world's biggest childhood killers, can be prevented through better environment management.

The four main diseases influenced by poor environments are diarrhoea, lower respiratory infections, various forms of unintentional injuries, and malaria.

Measures that can be taken now to reduce the environmental disease burden include the promotion of safe water storage and better hygienic measures, the use of cleaner and safer fuels, increased safety of the built environment, more judicious use and management of toxic substances in the home and workplace and better water resource management.

Diseases with the largest total annual health burden from environmental factors, in terms of death, illness and disability or Disability Adjusted Life Years (DALYs) are Diarrhoea (58 million DALYS per year, 94 per cent of the diarrhoeal burden of disease) largely from unsafe water, sanitation and hygiene, Lower respiratory infections (37 million DALYs per year, 41 per cent of all cases globally) largely from air pollution, indoor and outdoor.