A story in the National Geographic says “Seven million people die each year because of exposure to air pollution. That’s one in eight deaths across the globe, making air pollution the single greatest environmental health risk on Earth.” The estimate was reported this week by the World Health Organization; based on 2012 numbers, it is double the WHO’s previous 2008 estimate.
In some parts of the world, that pollution comes from fuel that is burned indoors for cooking.
More information is available at http://news.nationalgeographic.com/news/2014/03/140325-world-health-organization-indoor-fuel-pollution-death/