Theory 26/Knudsen Number/Inhaled particles
Deposition Is a Knudsen Problem
The claim
Where inhaled nanoparticles deposit in the lung is set by the Knudsen number, so the same mass of particles deposits differently depending on their size relative to the airway.
01Mechanism
Diffusive deposition dominates at high Knudsen, impaction at low; the transition sets regional dose.
02Prediction
Deposition pattern should track Knudsen.
03Refutation
Deposition tracking mass alone would remove the size ratio.