Environmental Engineering Reference
In-Depth Information
At a somewhat higher plane are investigations con-
ducted by local and state public health departments in which the primary
focus is air testing. Such investigations are done in response to a home-
owner/lessee request to determine by air testing what might be wrong with
their home. Air testing is usually limited to a few well-defined contaminants
for which methodologies and equipment are readily available, e.g., CO,
HCHO, and mold, and which have a history of being a potential cause of
contamination and health problems in dwellings.
Generic air testing, as an investigative protocol, has significant limita-
tions. Low contaminant levels based on one-time sampling are often inter-
preted as indicating that a problem does not exist. Such interpretations ignore
the often episodic nature of contaminant emissions and concentrations as
well as seasonal variations that occur with CO, HCHO, and mold. Air testing
results are often compared to guideline values that may not be sufficiently
health-based or protective of sensitive populations. Air testing tends to be
hampered by the “magic number” syndrome: levels above guideline values
are unsafe; levels below them are safe. Unfortunately, safe or acceptable
levels of exposure that protect the most sensitive or vulnerable populations
are less clear cut than guideline values, which are often based on what can
be reasonably achieved.
b.
Air testing.
To successfully conduct an IAQ/IE investi-
gation in a residential environment, it is essential that the investigator
approach the problem in a systematic manner. This includes pre-site-visit
information gathering, an on-site investigation and occupant interview(s),
conducting air/surface dust testing when appropriate, and evaluating poten-
tial causal factors and mitigation requirements when the on-site investigation
has been completed.
Pre-site-visit information gathering is typically conducted in a phone
interview with an adult building occupant (preferably the female head of
house). This limited interview should be designed to elicit information on
the perceived nature and history of the problem; symptom types and pat-
terns; house type, construction, age, and recent changes and renovations;
previous investigations and results; and any mitigation efforts. Information
gathered in the phone interview may be used in initial hypothesis formation
and in suggesting air testing and environmental sampling needs.
The on-site investigation typically provides information essential to suc-
cessfully diagnosing an IAQ/IE problem. The on-site investigation should
include a careful inspection of both the interior and exterior of the building.
This includes basement and crawlspace (and, in some cases, attic as well).
The investigator should be cognizant of any distinctive or unusual odors
that may indicate the nature of the problem or factors contributing to it.
These include chemical odors, pesticides, new carpeting and other new
materials, mold odor, etc. The investigator should be able to recognize mate-
rials, equipment, etc., that may be a source of health-affecting contaminants.
c.
Systematic approaches.
