Nearly a quarter of all deaths worldwide are caused by environmental risks like polluted air, dirty water, hazardous workplaces, and dangerous roads, according to the WHO report. The global health authority estimates that 12.6 million deaths in 2012, or about 23 percent of the total, were attributable to such factors.
The burden is greatest on the poorest people in the world, and on the youngest. Mortality from environmental risks is highest in sub-Saharan Africa and low- and middle-income countries in Asia.
The WHO report; which doesn’t count risks that depend on individual behavior, such as smoking and diet, looks at the environment broadly, including “physical, chemical, and biological factors external to a person” that can be modified. It focuses on environmental risks that are the product of the societal decisions that shape the world we live in.
There’s a big dose of guesswork in trying to estimate the global toll of unhealthy surroundings. The actual share of deaths attributable to the environment is most likely somewhere in the range of 13 to 34 percent, according to the report. To get to those numbers, the WHO examined studies on risks for more than 100 types of diseases and injuries: how air pollution affects cardiovascular disease, for example, or how workplace stress affects mental health. The group also surveyed more than a hundred experts.
The types of diseases involved have shifted in the decade since the WHO published a similar report. More people around the globe have gotten access to clean water, sanitation, and less harmful household cooking fuels. That transition has led to a decline in infectious diseases. At the same time, non-communicable diseases like heart disease and cancer account for a growing share of death and illness worldwide.
The good news is that the risks identified in the report are, by definition, modifiable. Straightforward measures such as greater access to clean water and hygiene could make an immediate impact. But because so much pollution and other environmental damage are consequences of commerce, fixing the problem would require changes to the way we do business.