Abstract: Particle detection devices for measuring the size distribution data of the parallel plate and screen diffusion types are disclosed in order to determine the distribution of ultrafine and attached particles in both analog and digital form. A gradual changing of the dimensions of the detector chambers is discslosed for varying the airstream velocity and for spreading out the plating out of the particles so that the distribution of different size particles can be determined. Recent improvements in health risk evaluation data indicate it is important to have detailed size distribution data for ultrafine particles in order to fully evaluate the health risks.

Abstract: A radon progeny detector for measuring the concentration of attached and unattached fractions in an atmosphere. A laminar flow of air is drawn sequentially through a diffusion screen and a particle trap. Unattached progeny having a particle size of 10 nm or less are captured upon the mesh of the diffusion screen. Attached progeny pass into the trap where the attached progeny are captured by a filter. Radiation detecting strips for recording radiation from alpha and beta particles emitted by the progeny are mounted on both sides of the diffusion screen and adjacent the particle trap to record the concentrations of both fractions.

Abstract: A radon progeny detector for measuring the concentration of attached and unattached factions in an atmosphere. A laminar flow of air is drawn sequentially through a diffusion battery and a particle trap. Unattached progeny having a particle size of 10 nm or less are captured upon the plates of the diffusion battery. Attached progeny is passed into the trap where the attached progeny is captured by a filter. Film strips for recording tracks produced by alpha particles emitted by the progeny are mounted in both the diffusion battery and the particle trap to record the concentrations of both fractions.