Influence of standard deviation on particle deposition

Regarding lung deposition one of the most important characteristic of an aerosol is particle size. Therefore a mean value is determined to describe the ability of an inhaled drug to reach its site of action. However standard deviation from this mean value influences the predictability of particle deposition.

With a mean particle size of 3 µm and a calculated standard deviation of 2, frequently observed with commercially available aerosols and nebulizers, still 10% of particles measure more than 7.2 µm and 10% about 1 µm. Therefore region of deposition becomes more or less uncertain.


Voshaar T. Therapie mit Aerosolen. 2005. Uni-Med: Bremen