Environmental Engineering Reference
In-Depth Information
Table 8.2
Risk Factors for Biological Contaminant-Associated IAQ/IE-Related
Health Problems
Contaminant
Risk factor
Mold
Obvious active/past mold infestation on building
materials
Building history of water damage
Wet building site
Musty odors
Culturable/viable airborne mold test results
(uninfluenced by outdoor mold sources) >1000
CFU/m
3
Sample results dominated by one or several mold
genera
Total mold spore counts >10,000 S/m
3
Positive allergy tests
Dust mites
Damp/moist interior building conditions
High (>2
µ
g/g) mite allergen levels in floor dust
samples
Positive allergy tests
Pet danders
Presence of pets in or near home
House history of pets (without pets necessarily being
present)
Positive allergy tests
High allergen levels in floor dust samples (cat
≥
1
µ
g/g)
Other allergens
Evidence of organisms present
Cockroach, birds, rodents,
crickets, spiders
Positive allergy tests
High allergen levels in floor dust samples (cockroach
≥
2 U/g)
Flue gas spillage and associated exposures to CO
and other combustion by-products commonly occur in residences. Such
problems have been reported in residences of all ages; they are, however,
more likely in older buildings. Carbon monoxide exposures are characterized
by symptoms of headache, extreme fatigue, sleepiness/sluggishness, and
even nausea. Risk factors include the presence of combustion appliances that
show some evidence of malfunction (loose flue pipes, flue pipe condensation
staining and/or corrosion); symptoms associated with the heating season;
measured CO levels >20 ppmv; carboxyhemoglobin (COHb) levels >2% in
nonsmokers not exposed in the workplace; and high CO levels emanating
from supply registers (indicating cracked heat exchangers).
Extreme care must be taken in diagnosing a CO problem. Flue gas
spillage is, by its very nature, episodic. As such it is not uncommon to
measure very low CO levels in a residence even though a CO exposure
problem exists. Blood tests for COHb may be desirable when a building
occupant reports symptoms. As CO exposures are common in small indus-
c.
Carbon monoxide.
