Environmental Engineering Reference
In-Depth Information
2.
Routine screening
Routine screening is a common sampling objective. Measurements are made
without any consideration of the probability that a contaminant is present
or the nature of health or other concerns. Common indoor contaminants are
measured using sampling instruments and techniques that are readily avail-
able, easy to use, and which do not impose an undue financial cost on
building owners or public health and environmental agencies.
Screening measurements have been, and continue to be, widely used by
homeowners/lessees and other building owners to determine radon levels.
Such measurements are designed to identify buildings with high radon
concentrations so that owners can implement appropriate mitigation mea-
sures to reduce exposure.
Routine screening is an important infection control measure in hospitals.
Of particular concern is the maintenance of low airborne levels of
Aspergillus
fumigatus
in surgical operating and convalescent patient rooms, as well as
oncology, transplant, and AIDS wards. Screening measurements for formal-
dehyde (HCHO) in urea-formaldehyde foam-insulated (UFFI) houses were
conducted by the Canadian government and many homeowners in both
Canada and the U.S. in the 1980s; such measurements are rare today. Mea-
surements of HCHO, CO, CO
, respirable particles (RSP), airborne mold,
2
and nitrogen dioxide (NO
) are commonly conducted in epidemiological
studies and problem building investigations.
On a population basis, such screening has the potential to identify indoor
environments that exceed guideline values and, as a consequence, are in
need of mitigation measures. Because of its generic nature, routine screening
has limited value in identifying specific causal factors responsible for build-
ing health complaints.
2
3.
Identifying causal contaminants
Ideally, environmental sampling is conducted to identify and quantify con-
taminants which, based on information gathered in an investigation, can
reasonably be expected to be a potential causal factor in occupant health
complaints. In some cases, the targeting of specific contaminants is facilitated
by: (1) unique symptomology (CO exposure, hypersensitivity pneumonitis);
(2) suggestive evidence that ventilation may be inadequate (human odor,
poorly designed/operated heating, ventilation, and air conditioning [HVAC]
systems); (3) odor (ammonia, solvents); (4) water-damaged materials and
evident mold infestation; and (5) occupant allergy tests that indicate sensi-
tivity to particular allergens.
Nonspecific mucous membrane and general (headache, fatigue) symp-
toms are commonly reported in many problem building and residential
investigations. They cannot easily be associated with unique contaminant
exposures. As a result, environmental sampling is unlikely to identify envi-
ronmental contaminants that may be causal agents.
