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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:

  1. Visual inspection of the building.
  2. Assessment of occupant symptoms.
  3. Evaluation of building performance.
  4. Monitoring of potential environmental sources.
  5. 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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