A link between air travel and deaths on the ground
The atmosphere is full of natural and man-made chemicals, including emissions from fuel combustion and byproducts of living organisms. Many of these chemicals combine in the atmosphere to form tiny solid and liquid particles known as “fine particulate matter” that are 2.5 micrometers or smaller (the average human hair is about 70 micrometers in diameter, by comparison). While it’s not clear whether all of these particles may be harmful, some are; the danger to humans comes when they are inhaled and trapped in the lungs, where they can then enter the bloodstream.In 2004, the World Health Organization estimated that about one million deaths per year are caused by air pollution, and several epidemiological studies have linked air pollution to the development of cardiovascular and respiratory illnesses, including lung cancer. Those studies tracked thousands of adults over many years to measure their exposure to air pollution while monitoring their health. Once...