About a quarter of all deaths globally are attributable to preventable environmental factors, such as air and water pollution, according to a new report by the World Health Organization.

The report, based on data from 2012, found that environmental risk factors accounted for about 12.6 million deaths out of a total of 55.6 million. One of the biggest scourges was air pollution, which caused not only lung and respiratory infections but also heart disease and cancer. Water pollution and poor sanitation contributed significantly to diarrheal diseases and infant mortality.

Africa and Asia had the most environmental deaths. The percentage of total deaths caused by environmental factors was unchanged from the previous W.H.O. report on the topic, which came out in 2006.