Pollution is the cause of one in four deaths among all children under five the world over، with toxic air، unsafe water، and lack of sanitation the leading causes، the World Health Organization (WHO) has found. A pair of reports simultaneously issued by the WHO found polluted environments cause the deaths of 1.7 million children annually، and many of the deaths could be prevented by interventions already known to work، such as providing cleaner cooking fuels to stop indoor air pollution. Harm from air pollution can affect children in the womb، and increase the risk of premature birth. After birth، air pollution raises the risk of pneumonia، a major cause of death for children aged under five، and lifelong lung conditions such as asthma. It may also increase the risk of heart disease، stroke and cancer in later life.