Case Studies in the Human Respiratory System - Computational Fluid and Particle Dynamics in the Human Respiratory System - page 251

efficiency in the drug delivery. In terms of modelling, the introduction of particles
involves a secondary phase (usually solid or liquid) to be present in conjunction
with the primary phase (usually gas or liquid), leading to the field of multiphase
flows. This case study presents different modelling strategies required to account for
a variety of particles that include spherical, non-spherical, and fibrous particles. A
brief description of each particle type is first given.

8.3.1 Characterisation of Toxic Particles

8.3.1.1 Wood Dust Particles

Wood dust is one of the most common organic dusts to which humans are exposed
due to the extensive use of wood for construction material and furniture (Enarson
and Chan-Yeung 1990). The International Agency for Research on Cancer estimated
that at least 2 million people in the world are exposed to wood dust occupationally
(IARC and WHO 1995). Exposure is common in many types of work, especially in
the primary wood industries such as logging, lumber mills, and pulp mills and even
more so in secondary wood industries such as cabinet making, furniture manufacture,
wood pattern and work shops, and other manufacturing industries (Enarson and
Chan-Yeung 1990). The processing of the raw timber from the use of high-powered
reciprocating tools, such as sanders and saws, generates large quantities of fine,
inhalable wood dust (Fig. 8.15 ). Direct contact with the wood dust leads to inhalation

Fig. 8.15 Wood dust
generated from different
wood turning stations. a
side-view of a hard cut of
camphor wood. b front-view
of a hard cut of camphor
wood. c finish cut of red gum
wood. d sanding of red gum
wood