Inertial Impaction

Deposition by inertial impaction occurs when particles of sufficient momentum cannot follow the abrupt directional changes in the airways. The particles instead follow their original direction, causing them to impact the airway walls when the air ducts change direction. The probability that a particle of diameter d and density p will diverge from an airstream of velocity u is characterized by the Stokes number [238]:

where h is the fluid viscosity and G is a constant that characterizes the geometry of the structure in which the particles are traveling. Therefore, deposition by impaction increases in proportion to (d^u). Inertial impaction is most significant for particles with large mass (determined by particle size and density) and/or velocity (determined by the respiratory flow velocity). Inertial impaction occurs mostly in the upper lung regions, since flowrates are high and changes in flow direction occur abruptly. Forced breathing increases particle velocity, thereby shifting particle deposition patterns towards the upper airways.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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