What happens to fluorides, hydrogen fluoride, and fluorine when they enter the environment?
Fluorides occur naturally in the earth’s crust where they are found in rocks, coal, clay, and soil. They are released into the air in wind-blown soil. Hydrogen fluoride is released to the air from fluoride-containing substances, including coal, minerals, and clays, when they are heated to high temperatures. This may occur in coal-fired power plants; aluminum smelters; phosphate fertilizer plants; glass, brick, and tile works; and plastics factories. These facilities may also release fluorides attached to particles. The biggest natural source of hydrogen fluoride and other fluorides released to the air is volcanic eruptions. Fluorine cannot be destroyed in the environment; it can only change its form. Fluorides released into the atmosphere from volcanoes, power plants, and other high temperature processes are usually hydrogen fluoride gas or attached to very small particles. Fluorides contained in wind-blown soil are generally found in larger particles. These particles settle to the gro
