Abstract
Using dimensional analysis, an expression is derived for the dependence of the particle removal efficiency of the lower lung on the particle diffusion coefficient, the time per breath and parameters related to the structure of the lung. The analysis is limited to particles smaller than a few tenths of a micron in diameter, for which diffusion is the controlling mechanism of removal. It is not necessary to assume a special model for the structure of the lung. The analysis can be used to correlate and extrapolate experimental data; it can also be used to predict the size of the largest particle which is (almost) completely removed in the respiratory region.