The diameter of a unit density sphere (density = 1 µg/cm3), which has the same settling velocity as the particle in question
Diameter of a spherical particle of unit density which has the same settling velocity in air as the particle in question. IPCS, 1987
Refers to the size of particles. It is the diameter of a sphere of unit density that behaves aerodynamically (has the same settling velocity in air) as the particle of the test substance. It is used to compare particles of different size, shape, and density, and to predict where in the respiratory tract such particles may be primarily deposited.
The diameter of a spherical particle having a density of 1 gm/cm3 that has the same inertial properties (i.e. settling velocity) in the gas as the particle of interest.
The diameter of a unit-density sphere having the same terminal settling velocity as the particle in question. It is used to predict where in the respiratory tract such particles will deposit.1
diameter of a unit-density sphere having the same gravitational-settling velocity as the particle in question.1 Aerodynamic diameter takes into account the shape, roughness, and aerodynamic drag of the particle. Used for movement of particles through a gas.2
Expression of aerodynamic behavior of an irregularly shaped particle in terms of the diameter of an idealized particle; that is, aerodynamic diameter is the diameter of a sphere of unit density that has aerodynamic behavior identical to that of the particle in question. Thus, particles having the same aerodynamic diameter may have different dimensions and shapes.
The diameter of a sphere with unit density that has aerodynamic behavior identical to that of the particle in question; an expression of aerodynamic behavior of an irregularly shaped particle in terms of the diameter of an idealized particle. Particles having the same aerodynamic diameter may have different dimensions and shapes.
Drug particles for pulmonary delivery are typically characterized by aerodynamic diameter rather than geometric diameter. The velocity at which the drug settles is proportional to the aerodynamic diameter, da.