Environmental Engineering Reference
In-Depth Information
Figure 2.6
Asbestos exposure hazard assessment algorithm.
from 1 to 7. Lowest numbers indicate a potentially high risk of exposure and
thus a high abatement priority; highest values represent relatively low asbes-
tos exposure hazards. The USEPA decision tree takes both the condition of
ACBM and its potential for disturbance (accessibility, vibration, and air
erosion) into account.
In algorithm methods, a numerical score is assigned to a number of
factors (
Figure 2.6
)
which may affect exposure. These include ACBM condi-
tion, water damage, exposed surface area, accessibility, activity/movement,
friability, asbestos content, and the presence of an open air plenum or direct
airstream. The significance of the algorithm in
Figure 2.6
is that it considers
important factors that the USEPA's relatively simple decision tree ignores.
Intuitively, one would expect that the surface area exposed and percent
asbestos content would increase the potential for exposure. Water damage
would also be a significant potential exposure factor since it is one of the
major causes of damage to SM such as acoustical plaster, often causing
delamination from the substrate and fiber release episodes. Though visual
inspections and the use of USEPA's decision tree are standards for exposure
hazard assessments in school buildings, and occasionally in other buildings,
such assessments have not been successful in predicting airborne asbestos
fiber concentrations.
D. Health effects
Exposure to elevated airborne levels of asbestos fibers have definitively been
shown to cause disease. These include fibrotic disease of the lungs and pleura
