The Physical Significance of Size Measurements

The reciprocal of the Aspect Ratio has recently become quite widely used to describe the shape of fmeparticles. The reciprocal quantity is called the Chunkiness of the fineparticle. (The physical significance of this measure will be discussed in Chapter 2.) 

when choosing a method of size characterization, one should always choose a method close to the operational context for which the information is required. Thus if one wants to study the dust movement into and out of the lung one should use a method that actually measures the aerodynamic size of the fineparticle. 

---