Relatively little information is available about the quantity and form of boron in the atmosphere. Boron has been detected in measurable quantities in evaporation from seawater, rain, snow, and hot springs, and industrial airborne dust. In rain and snow, boron has been reported in concentrations ranging between 0.002 and 0.1 milligrams boron per liter. The major source of boron in the atmosphere appears to be evaporation from seawater. Industrial processes contribute much less. On a global basis, boron moves through the atmosphere at a rate of five to seven million tons per year.