Nearly one in four deaths worldwide can be linked to unhealthy environments.

The World Health Organization (WHO) made that conclusion in a report they released early today.

The agency said an estimated 12.6 million people died in 2012 as a result of living or working near unhealthy places.

Factors included air, water, and soil pollution. WHO also pointed at secondhand smoke, chemical exposure, climate change, and ultraviolet radiation.

Officials said those environmental factors contribute to more than 100 types of diseases and injuries.

The highest number of deaths related to the environment were from low- to middle-income countries in Southeast Asia, the Western Pacific, and Africa.

WHO also reported high percentages of deaths related to cardiovascular disease and cancers. These cases were found in higher-income nations in Europe, South America, and North America.

“A healthy environment underpins a healthy population,” Dr. Margaret Chan, WHO director general, said in a statement. “If countries do not take actions to make environments where people live and work healthy, millions will continue to become ill and die too young.”

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Who, Where, How

The study is an update from a WHO report published a decade ago.

In today’s report, WHO officials stated that 3.8 million environment-related deaths in 2012 occurred in Southeast Asia, the world’s most populous region.

Another 3.5 million deaths happened in the Western Pacific. In Africa, 2.2 million deaths were linked to environmental factors.

About 1.4 million deaths were in Europe. In the eastern Mediterranean region, there were 854,000 deaths. In the Americas there were 847,000 deaths.

Young children and older adults have the greatest risk for environment-related deaths, WHO officials said.

Lower-respiratory infections and diarrhea-related diseases mostly impact children. Older people tend to have noncommunicable diseases such as stroke, heart disease, cancer, and chronic respiratory disease.

The researchers estimated that the deaths of 1.7 million children under age 5, and 4.9 million adults ages 50-75, could be prevented by better environment management.

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The Environmental Factors

The number one environmental danger is air pollution, the WHO report concludes.

It is estimated that 8.2 million deaths are linked to poor air quality. That includes exposure to secondhand tobacco smoke.

The report adds that since the initial study the number of deaths from infectious diseases such as diarrhea and malaria have declined.

WHO officials credit safer water, better sanitation, increased immunization, and insecticide-treated mosquito nets.

The report lists a number of other cost-effective methods that can reduce environment-related deaths. Countries can reduce the use of solid fuels for cooking and increase access to low-carbon energy technologies.

“There’s an urgent need for investment in strategies to reduce environmental risks in our cities, homes, and workplaces,” Dr. Maria Neira, WHO’s director of the Department of Public Health, Environmental and Social Determinants of Health, said in a statement.

“Such investments can significantly reduce the rising worldwide burden of cardiovascular and respiratory diseases, injuries, and cancers, and lead to immediate savings in healthcare costs,” Neira explained.

Increasing access to safe water, expanding sanitation efforts, and promoting hand washing would also help, WHO officials said.

They also note that enacting anti-tobacco legislation, improving urban transit capabilities, and building energy-efficient housing could improve air quality.

The report authors highlighted Curitiba, Brazil. The city has heavily invested in slum upgrading, waste recycling, and a popular “bus rapid transit” system. There have also been green spaces and pedestrian walkways incorporated to encourage walking and cycling.

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