Environmental Engineering Reference
In-Depth Information
Total mold spore and particle sampling devices have a significant advan-
tage over culturable/viable samplers in one regard: because all mold parti-
cles are potentially allergenic, these devices are likely to better quantify
health exposure risks. Because of the advantages and limitations of each, it
is desirable to conduct concurrent sampling with culturable/viable and total
mold spore/particle sampling devices to better interpret sampling results.
3. Biological aerosol sampling considerations
Though similar principles apply to all air sampling activities, there are sam-
pling considerations unique to biological aerosols.
a. Limitations.
The primary objective of biological aerosol sampling
is to measure airborne concentrations of biological contaminants such as
mold, bacteria, or actinomycetes in problem environments to determine
whether measured levels are excessive or within acceptable limits. Unfortu-
nately, there is no consensus as to what excessive or acceptable levels are.
This reflects, in part, the fact that fluctuations in concentrations of an order
of magnitude may occur in an environment over a period of days to months.
In such a context, measured values, particularly at the low end of the range,
are not meaningful and are even misleading. As a consequence, expert com-
mittees (such as the ACGIH Bioaerosols Committee) do not recommend the
use of biological aerosol sampling results as a measure of exposure. Rather,
sampling is recommended for the purpose of identifying sources in conjunc-
tion with building inspections. Nevertheless, biological aerosol sampling is
widely used in problem building investigations and in evaluating the efficacy
of remediation measures.
b. Area vs. aggressive sampling.
There are two basic approaches to
sampling airborne biological contaminants, area and aggressive sampling.
Area sampling may be conducted to determine the concentrations and types
of organisms that may be present in indoor spaces. It may also be conducted
to determine the efficacy of remedial measures. Aggressive sampling is used
to identify or confirm sources of mold/bacteria/actinomycete infestation by
sampling after disturbance. Aggressive sampling may be used to evaluate
the efficacy of remedial measures used in controlling toxigenic fungi.
c. Culturable/viable sampling.
i. Media selection. As indicated previously, media selection is a very
important consideration in sampling biological aerosols. Media should
reflect sampling objectives. It is important to understand the limitations and
advantages of each medium used in biological aerosol sampling.
ii. Location and number. As with other airborne contaminants, sam-
pling locations should reflect specific objectives. Samples should be collected
