Environmental Engineering Reference
In-Depth Information
Figure 6.2
Asexual spores and spore bearing structures of
Penicillium
. (Courtesy of
University of Minnesota.)
quence of evolutionary processes, fungal spores have size and aerodynamic
properties that enhance airborne dispersal. Spores vary in size (2 to 100
m),
with the smallest being single cells and the largest being multicellular. Spores
of
µ
which illustrate different spore shapes and
sizes, can be seen in
Figures 6.4
and
6.5
.
Spore dispersal may occur by passive or active release mechanisms, with
subsequent entrainment and movement by horizontal or convective air cur-
rents. Once airborne, spores may be carried varying distances, depending
on their aerodynamic properties as well as existing atmospheric conditions.
In still air (such as may occur in houses) they settle out relatively rapidly.
Based on Stokes Law, the largest and heaviest spores would settle out more
quickly, with smaller spores being suspended for longer periods of time.
Alternaria
and
Cladosporium,
Figure 6.3
Asexual spores and spore-bearing structures of
Aspergillus
. (Courtesy of
University of Minnesota.)
