Models of Lung Retention Based on ICRP

Abstract

In aerosol exposures, it is important to determine the concentrations of deposited particles in the respiratory tract and correlate that with various factors describing the aerosol. Using a four-compartment lung model (with specified clearance times from each compartment), we have derived expressions and written Fortran IV programs to calculate particle retentions. Three exposure patterns were considered: continuous chronic, acute pulse, and 40-hour work week exposures. Particle concentrations in each compartment at any time and integrated exposure over any period were calculated for each pattern. Results show that changes in particle size and solubility can alter retention and integrated exposure in some compartments by orders of magnitude, even when identical masses of aerosol are inspired. Thus, air quality standards must take size distribution and solubility of the particle into account.