The methods for measuring the mass of fine particles suspended in the air are being studied in National Metrology Institute of Japan. In these methods, either the balance between the centrifugal and electrostatic forces or between the gravitational and electrostatic forces exerted on particles is used to classify particles according to their mass to charge ratio. These methods have been applied to the analysis of particulate matter emitted from motor vehicles in Atlanta, GA, and to the development of particle size standards.

AIST Today Vol. 1, No. 5 (2001) 11