Long-term exposure to air pollution was shown to be associated with more osteoporosis-related bone loss and greater risk for bone fractures in two studies published in The Lancet Planetary Health (November 2017). Osteoporosis is a disease in which bones become weak because more bone mass is lost than can be rebuilt. For one study, researchers analyzed data on over 9 million Medicare patients hospitalized for osteoporosis-related bone fractures. The risk for such hospitalization was greater in areas with elevated levels of PM2.5, which is a component of air pollution. Even a slight increase in air pollution was linked to greater risk for fractures, and the risk was particularly high in low-income communities. A second study of 692 adults found that those living in areas with high levels of PM2.5 had lower levels of a key calcium and bone-related hormone and lower bone density.