Environmental Engineering Reference
In-Depth Information
Table 5.6
Relative Concentration Categories of Mite, Cat,
and Dog Allergens in House Dust (
µ
g/g)
House dust mite
Cat
Dog
Category
Der p1
Der f 1
Fel d 1
Can f 1
Very low
<0.5
<0.5
<0.1
<0.3
Low
0.5-5
0.5-5
0.1-1.0
0.3-10.0
Intermediate
>5-15
>5-15
>1-10
>10-100
High
>15-20
>15-20
>10-100
>100-1000
Very high
>20
>20
>100
>1000
Source:
From ECA (European Collaborative Action “Indoor Air
Quality and its Impact on Man” COST Project 613),
Biological
Particles in Indoor Environments
, Report No. 12 EUR 14988EN,
Office for Publications of the European Communities, Luxem-
bourg, 1993.
Highest mite populations occur in residential buildings; significantly
lower concentrations are reported in institutional buildings such as schools,
nursing homes, and office buildings. In office/commercial buildings, mite
populations are rarely >20 to 40 mites/g dust, whereas mite populations
>100 mites/g are common in many residences. Allergen levels >2
g/g are
very uncommon in institutional and commercial buildings. Dust mites are
approximately 4 times more prevalent in residences with wall-to-wall car-
peting compared to those with bare floors or area rugs. Carpeting appears
to provide a favorable environment for the collection and decomposition of
human skin scales. It also provides an environment with relative humidity
levels above minimum requirements for dust mite survival.
Mite fecal pellets are large (10 to 35
µ
m). As a consequence, disturbance
of floor and other surface dusts is necessary to disperse them in air. Because
of their large size and mass, they settle out rapidly and do not form true
aerosols in the fashion of cat dander and mold spores. Consequently, expo-
sure is episodic and is typically associated with bed disturbances during
sleep, bed-making, and house-cleaning activities. Only the smallest of par-
ticles in the fecal pellet range have the potential to enter and deposit in the
upper respiratory system.
Though mite allergens are the most common cause of immunological
sensitization resulting in symptoms of chronic allergic rhinitis and asthma,
other allergen-producing mites may be present in building environments.
Most notable of these are stored product mites such as
Tryrophagus putres-
centiae
and
Glycophagus domesticus
.
µ
V. Insects
A number of insects have been identified as sources of inhalant allergens
that may cause chronic allergic rhinitis and/or asthma. These include cock-
roaches, crickets, beetles, moths, locusts, midges, and flies. The best-studied
