Environmental Engineering Reference
In-Depth Information
smarting, stinging irritation, hoarseness, or voice problems; neurotoxic/gen-
eral health problems such as headache, sluggishness, mental fatigue, reduced
memory, reduced concentration, dizziness, intoxication, nausea, vomiting,
and tiredness; skin irritation such as pain, reddening, smarting, itching sen-
sations, or dry skin; nonspecific hypersensitivity reactions such as runny
nose or eyes, asthma-like symptoms among nonasthmatics; and odor and
taste sensations such as changed sensitivity of olfactory and taste senses, or
unpleasant odor and taste.
In defining SBS, the WHO panel concluded that: (1) the major symptoms
are mucous membrane irritation of the eyes, nose, and throat; (2) symptoms
should appear especially frequently in individual buildings or parts thereof;
(3) a majority of occupants should report symptoms; and (4) there should
be no evident symptom relationship to occupant sensitivity or excessive
exposures.
The WHO characterization of SBS appears to be based on the theory that
SBS complaints of a sensory nature occur as a consequence of the nonspecific
irritation or overstimulation of trigeminal nerves (responsible for the com-
mon chemical sense) in mucous membranes. Trigeminal nerves respond to
chemical odors, producing sensations of irritation, tickling, or burning. Expo-
sure to many different chemicals produces similar responses.
Within this context, a WHO committee has suggested that indoor air
contains a complex of sensory stimuli that produces irritant responses not
specific to individual contaminant exposures. As a consequence, no single
contaminant is likely to be responsible for SBS. Reactions of the “referred
pain” type may take place (i.e., headaches that may be due to the irritation
of trigeminal nerves). Following absorption of contaminants on nasal
mucosa, upper respiratory symptoms would occur as a result of numerous
subthreshold stimulations.
As defined by WHO, SBS is a phenomenon in which high prevalence
rates of illness symptoms occur in buildings with no single apparent causal
factor responsible. This concept of SBS suggests that reported symptoms are
due to collective exposure to a variety of chemical substances present at low
concentrations.
The concept of SBS was defined in the early 1980s at a time when there
was little understanding of causal or risk factors for illness symptoms in
building occupants. It was also defined at a time when ventilation rates used
in buildings were relatively low, and emissions from various building mate-
rials, furnishings, finishes, etc., were high. Since that time, building ventila-
tion rates have increased and emissions from materials have decreased. As
a result, our early understandings of SBS as a unique phenomenon are less
applicable today.
Scientific studies conducted over the past two decades suggest that a so-
called “sick building syndrome” may not in fact exist. SBS-type symptoms
reported in any individual building are likely to be multifactorial in origin,
i.e., a variety of exposures occurring at the same time may be responsible
for the reported symptoms.
