Direct measurements of stratospheric fluoride

Stratospheric fluoride mass mixing ratios were measured by passing stratospheric air through filters half of which is impregnated in a base. Measurements of stratospheric fluoride were obtained at altitudes from 15 to 40 km at latitude 30-33 N and longitude 95-105 W at different months of the year. The significant amount of fluoride collected on the base-impregnated portion of the filters suggests that fluoride is present in the stratosphere as an acid gas. The mixing ratios decrease markedly at altitudes less than 20-25 km, suggesting the troposphere as the major sink for stratospheric fluoride.