Median aerodynamic diameter


Median aerodynamic diameter is one of two parameters influencing the deposition of inhaled particles, the other being the geometric standard deviation of the particle size distribution. The MAD is the value of aerodynamic diameter for which 50% of some quantity in a given aerosol is associated with particles smaller than the MAD, and 50% of the quantity is associated with particles larger than the MAD. It simplifies the true distribution of aerodynamic diameters of a given aerosol as a single value. It is used to describe those particle sizes for which deposition depends chiefly on inertial impaction and sedimentation.

Activity median aerodynamic diameter

In the context of radiation protection, activity median aerodynamic diameter is the MAD for the airborne activity in a given aerosol. Internal dosimetry uses it as a means of simplifying the true distribution of aerodynamic diameters of a given aerosol.

Count median aerodynamic diameter

Count median aerodynamic diameter is only used rarely. Half of the particles of a given aerosol have the aerodynamic diameter smaller than the CMAD, and the other half larger. A similar quantity, count median diameter is more common.

Mass median aerodynamic diameter

Mass median aerodynamic diameter is the MAD for mass.