Mold Testing Standards

The first question is "in what State is this project?". Some States (i.e., Texas) have licensing requirements for fungal growth (mold) consultants and remediators. Most States do not have licensing or certification requirements. I would suggest you get a Certified Industrial Hygienist (check their credential at www.abih.org) who is knowledgeable in fungal growth assessment and control. I am not familiar with NOCA and could not find it when I searched the internet. What is that?

There are no standards for airborne fungal levels. Typically indoor fungal levels are compared to either a control indoor area (no complaints or fungal growth) or, more commonly, outdoors. Since outdoor airborne fungal spore levels vary greatly across the country each area must be specifically addressed.

There are several ASTM standards for fungal growth assessment and sampling with which I have been involved. ASTM E2418-06 "Standard Guide for Readily Observable Mold and Conditions Conducive to Mold in Commercial Buildings: Baseline Survey Process", which is in the process of being updated, is good for evaluating a building for moisture intrusion or conditions conducive to moisture intrusion. Hopefully the revised version will be published early next year. It is solely a visual process.

There is also ASTM D7338-14 "Standard Guide for Assessment of Fungal Growth in Buildings" (also visual with references for further evaluation) and D7788-14 "Collection of Total Airborne Fungal Structures via Inertial Impaction Methodology" which is a brand new standard we just finished. The D22.08 Subcommittee on Sampling and Analysis of Mold has generated several other standards for fungal assessment as well as several other proposed standards including one titled "Practice for Post Remediation Verification of Fungal Contamination in Buildings". This one would be the most appropriate for your question. Unfortunately, this PRV standard will probably take a while because it is a very controversial issue. Each consultant has their own way of doing a PRV. I have a Powerpoint presentation on conducting PRVs and have published an article on it, if you are interested in my approach. There is also an American Industrial Hygiene Association (AIHA) document titled "Assessment, Remediation, and Post-Remediation Verification of Mold in Buildings" (www.aiha.org).

When it comes to doing air testing for airborne fungal spores it should be noted that there are several methods and great care must be taken when interpreting results. The ASTM methods recognize that visual assessments are the best approach. Air testing should only be used as a tool when testing a very specific hypothesis. There is a lot of error involved with the testing methods currently available.

Personally I would do a thorough visual assessment of the moisture affected areas in your building, including destructive testing, to determine that fungal growth has been thoroughly removed (note that lined ductwork cannot be disinfected or sterilized or even cleaned very well) I would do this after assurances have been made that the cause of the moisture/water intrusion has been corrected. If needed replacement wall materials should not have cellulose (i.e., no paper coated drywall). After the visual assessment I would collect three to five spore trap samples (see ASTM D7788-14) in each area served by the affected AHUs. I would also do two to four outdoor samples for comparison. The indoor samples should have similar or less levels of both total spores and individual types of spores. The lab I use has a great database of what may be commonly found outdoors in most parts of the country. This can also be used to determine if the indoor individual spore type levels are background or not. A rule of thumb with this method is that there is a significant difference (i.e., meaning the levels are truly lower or higher) in spore levels when there is an order of magnitude difference in counts from one sample to another.

Your question exposes a very contentious issue in the realm of indoor air quality (IAQ). We in the profession have been grappling with this since the early 1990s with little definitive results. It is also the most litigious aspect of IAQ consulting, As the ASTM D22.08 subcommittee and other ASTM committees establish national consensus standards on this issue hopefully it will become clearer.

Dale Walsh, MS, CIH, LEED-AP BD+C
Walsh Certified Consultants, Inc.
Las Vegas, Nevada
702-468-4782