Environmental Engineering Reference
In-Depth Information
there was an increased prevalence of eye and upper respiratory system symp-
toms, face rash, headache, and abnormal tiredness among children in school
buildings with wall-to-wall carpeting compared to those with hard floor cov-
ering. In Danish schools, asthmatic children were reported to have more severe
asthmatic symptoms in carpeted buildings. A significant association between
SBS-type symptoms and carpeting was observed in both Canadian and Cali-
fornia office buildings. However, no relation between carpeting and SBS-type
symptoms was observed in a Dutch study of office buildings.
In addition to these epidemiological studies, Danish studies of human
exposures to carpet emissions under controlled laboratory chamber condi-
tions have shown significant symptom responses among asthmatic and non-
asthmatic subjects after a 6-hour exposure to rubber-backed nylon carpeting.
These increased symptoms included head feeling heavy, tiredness, eye irri-
tation, itchy/runny/congested nose, and facial itching/burning.
Carpeting serves as a sink for a variety of contaminants. These include
VOCs and SVOCs that are emitted from carpeting and other sources which
are adsorbed on, and released by, carpeting. Fleecy material such as carpeting
has a large specific surface area (total surface area per weight or volume). As
such, carpet has a large capacity for adsorbing a variety of VOCs and SVOCs.
In addition to VOCs and SVOCs, carpeting serves as a reservoir for
organic particles. These include human skin scales, pet danders, insect and
mite excreta and body parts, plant materials, viable and nonviable mold
spores/hyphal fragments, and bacteria. One of the strongest correlations
between illness symptoms in the Danish municipal building study was with
the macromolecular organic fraction (MOD) of surface dust and individual
volatile compounds associated with it. Both mold and bacteria are likely to
grow on organic dust found on carpets and other fleecy surfaces. However,
at this time, there is little evidence that such dust and the presence of
carpeting significantly increased airborne exposure to culturable/viable
mold or bacteria. Carpeting is a major reservoir for allergenic substances
such as cat, dog, and dust mite allergens. Though commonly present, dust
mite allergen levels in nonresidential buildings are low (<1
g/g) compared
to residential buildings. As such, exposures are likely to cause, at worst, a
minimum risk of sensitization in nonsensitized individuals and symptom
initiation in those who are. Significant levels of both cat and dog allergen
have been found in carpeting of elementary and other schools. Cat allergen
in carpeted schools appears in concentrations sufficient to cause both sensi-
tization and symptoms in sensitive individuals. Though dog allergen levels
are high, there are as yet no exposure guidelines available to evaluate the
significance of dog allergen in floor dust samples. It is worth noting that, in
the Swedish school study described above, symptoms were associated with
older, soiled carpets and mostly resolved when carpeting was removed.
ยต
Compared to textile carpeting, vinyl floor cov-
ering has received relatively little attention as a risk factor for SBS-type
b.
Vinyl floor covering.
