When Is Sampling for Microbiological Contamination Appropriate?

IAQ Investigations

All indoor air quality investigations begin with an indoor environment inspection. Visual inspection is a process by which a building investigator employs specific talents, skills, and equipment to formally document IAQ events. If a contaminant is observed during the inspection, the question actually facing the investigator becomes one of practicing due diligence, that is, what are trying to identify or prove. This varies by client and situation.

No Indoor Microbiological Standards

Inspectors should align their investigatory practices with accepted regulatory standards. One of these industry standards, the bible of mold world, is Bioaerosols: Assessment and Control. We identify and document the conditions that exist and develop an initial hypothesis, which is, based on the conditions present, what we believe the magnitude of the problem is. At this point we must decide if sampling and laboratory analysis provides any more useful information in an effort to correct the problem. Dr. Philip Morey and Dr. Harriet Burge are two of the leading experts in indoor microbial contamination. They have described in various publications when microbial sampling is justified in IAQ investigations. Dr. Burge documented the need to obtain active source samples in a Bioaerosols: Assessment and Control. Also, according to Dr. Morey, there are five occasions when microbial sampling is appropriate:

• To validate a medical hypothesis; Are you working with a doctor to treat some level of exposure?
• To provide supportive remediation data. Traditional remediation with containment requires background readings to prove that the contractor did not make the “unaffected areas” worse. Decontamination does not and saves time and money.
• To support or refute litigation or insurance claims. Atoorneys will want to fully document the extent of the contamination prior to establishing a strategy.
• To conduct research
• To identify potential toxigenic species relative to OSHA's "Right to Know" standard

Absent these conditions, a valid case can be made to not take samples. It all gets back to, “How will the results of sampling and laboratory analysis be used?” Other inspectors in the industry will take samples no matter what; it is included in their base price and is not in the best interest of the client. This type of approach can provide a false sense of security that may not exist.