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Problem-building investigations require many different
levels of expertise. When an IAQ investigation also requires bioaerosol
sampling a clearly defined sampling plan should be developed before
any sampling is performed.
While the ACGIH guidelines provide a solid foundation to help us determine
where to collect samples. There are still many variables that come into
play in any bioaerosol investigation, but the information provided by
the ACGIH helps to summarize where to collect samples to compare anticipated
high and low exposures.
The ACGIH Bioaerosols Committee has developed guidelines for the assessment
and control of bioaerosol exposures. These guidelines suggest five activities
for evaluating bioaerosol exposures and for recommending control measures:
- Visual inspection of the building.
- Assessment of occupant symptoms.
- Evaluation of building performance.
- Monitoring of potential environmental sources.
- Application of professional judgement.
The information collected through air monitoring is only one of the
factors that should be considered when
selecting the approach to use when bioaerosol exposures are suspected.
Reliance on the "numbers" alone
may result in inappropriate decision-making due to the limitations of
this monitoring. Application of professional judgement towards a testable
hypothesis is imperative.
A very important component of the sampling plan is where to collect
samples. Since there are few Threshold Limit Values (TLVs) for bioaerosols
in most situations, it is important when developing the sampling plan
to collect enough relevant data to be able to compare complaint vs.
noncompliance vs. outdoor data to develop an accurate picture of potential
problems. Listed below are the sampling recommendations from the all
new ACGIH "Bioaerosols Assessment and Control" reference guide
(ISBN - 882417-29-1, Page 5-5, Table 5.4). This text has become the
reference guide of choice for most IAQ investigators and orange coast
INSPECTION
uses it extensively.
Tentatively identify bioaerosol sources (e.g., HVAC system components,
building materials, or furnishing that are visibly contaminated with
microbial growth or that show signs of water damage) and estimate their
source strengths (i.e., bioaerosol generation rates). Predict spatial
and temporal bioaerosol concentration gradients. Identify zones with
expected differences in bioaerosol kind or concentration (e.g., indoor
and outdoor sites as well as areas near suspected sources and control
areas).
Identify occupants anticipated to receive the highest and lowest exposures
and show the strongest and weakest reactions based on their proximity
to potential sources, types of activities conducted, and medical conditions.
Identify areas which investigators will be allowed access. Identify
areas that can be monitored without disrupting typical occupant activities.
Select at least one, preferably three, sampling locations in each of
the following areas.
1. An anticipated high-exposure area
2. An anticipated low-exposure area
3. Outdoors near air intakes for the building
If applicable, also sample at the following locations
1. Outdoors near potential sources of bioaerosols that may enter
the building
2. Outdoors high above grade and away from potential bioaerosol sources
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