Don Weekes, CIH, CSP – New AIHA Mold Document & Industry Update – AIHA FAQ’s About Spore Trap Air Sampling for Mold for Direct Examination

Air Date: 6-7-2019|Episode 549

This week on IAQ radio we welcome back one of our favorite guests to talk about a new AIHA mold document and some other industry current events. Donald Weekes was a Partner at InAIR Environmental, Ltd. an occupational and environmental health and safety consultancy based in Ottawa, ON. He is now a full-time volunteer. Mr. Weekes has been providing environmental and occupational health and safety technical assistance for more than forty-three (43) years.

Mr. Weekes is a Certified Industrial Hygienist (CIH) and Certified Safety Professional (CSP). He is currently a Director of the American Conference of Governmental Industrial Hygienist (ACGIH). He is a Past President of IAQA (Indoor Air Quality Association), as well as Past President of the Ottawa Valley Chapter for ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers). Besides these professional organizations, Mr. Weekes has also involved as a volunteer with the following professional organizations: American Industrial Hygiene Association (AIHA), International Society of Indoor Air Quality (ISIAQ), Canada Green Building Council (CaGBC).

Z-Man’s Blog:

“The New AIHA Mold Document & Industry Update”

Over the years, Don Weekes, CIH, CSP has been a frequent guest on IAQradio. Don has 44 years of industrial hygiene and safety experience. Don Weekes describes his current occupation as fulltime volunteer. One condition of the sale of his business (InAIR Environmental) was that he committed to assist the buyer for 17 months aiding in business transition/succession and to helping support and training the field staff.

Nuggets Mined from Today’s Episode:

At an IAQA conference Don took part in debates on 2 IAQ issues:

1)  When air sampling for PRV, should AFD’s be on or off?

2)  When 1 spore of Stachybotrys shows up in an air sample, does the remediator fail PRV?

  • When air sampling should AFD’s be on or off? As both AFD’s and HVAC systems both suck air (as does the air sampling equipment), Don’s position was that both AFD’s and HVAC should both be off during sampling.
  • When 1 spore of Stachybotrys shows up in an air sample, does the remediator fail PRV? Don explained that preparation is the key to remediation. He sits down with the contractor before the job and discusses his monitoring process (visual inspection, particle counts outside the containment in occupied buildings, and if, when, where, the type of sampling that will be done, and how long before sampling should AFD’s and HVAC should be shut down?) Don’s position is that promulgation of “1 spore of Stachy fails” is a bad idea. When queried about “what if 2 spores of Stachy are found”, he referred to this being twice as wrong. He advocates that visual inspection is the best method for PRV, not air sampling. Air sampling is only confirmatory of the findings of the visual inspection, and not to be used to override the visual inspection. In the event remediator fails a visual inspection, recleaning is required.

What led to the AIHA’s new document? 2 years ago, Don was present at a presentation at Seattle AIHce on air sampling where the presenter mentioned that a mold lab represented that 6-7 million mold spores could be found in a simple air sample. Don felt that this was physically impossible and that something was wrong (equipment problems, reporting errors, sampling errors, counting errors, etc.). In accordance with the EMPAT rules, the quality controls for air sampling is qualitative not quantitative.

If you want the answers to these questions:

Q:  Does a correlation exist between culture based and direct examination sampling?

Q:  What are the differences and limitations of using direct examination versus culture-based methods?

Q:  What variables in environmental conditions can influence sample collection?

Q:  What considerations should be given to temporal variabilities in airborne mold concentrations when sampling for mold?

Q:  When collecting and analyzing samples, what considerations should be given to account for analytical variability of results?

Q:  How many samples should be collected?

Q:  Does an analytical method to analyze airborne direct examination mold samples exist?

Q:  Is there an upper limit to spore counting results?

Q:  What is the difference between EMPAT participation and EMLAP accreditation?


Don credits Cheri Marcham ( for her leadership on the project.

In 1992, David Miller, PhD pointed out temporal variability of air samples taken at different times of the day being as great as 10,000-fold.

According to Don, there should never be more than 1,000,000 spores in an air sample. Numbers like 7,000,000 create public anxiety, the public wants an explanation for why the number is so high? The labs are analyzing a small portion of the air sample and extrapolating that the rest of the sample is similar in mold spores. This leads to the elevated mold spore counts that the labs are reporting.

Don recommends speaking to the lab director in the event you have samples with counts over 1,000,000.

Inspections and sampling are conditional, what was or wasn’t happening at the time the sample was taken.

In building comparisons of effected verses unaffected areas is fair.

IEPs must be careful with any type of sampling. There are climate differences, construction differences, equipment differences, etc. Clients don’t like to wait 7-10 days for culturable samples. Clients who want to “just see what’s in the air” should be dissuaded from air sampling. Sampling and analysis have anticipated error rates of 30%-200%. Due to errors, air sampling may not provide a true representation of what is present.

Clients should be provided with an accurate representation of what is present, and what is the variation in the sampling results.

Don is on the ACGIH board of directors. The board has authorized reviving the Bioaerosols Committee to look at the TLV booklet’s Section on Bioaerosols, and to determine if a market exists for a revised Bioaerosols book (1999)? The possible second editions of the Bioaerosols book caused heartburn when individuals from AIHA and ACGIH met 5 years later to discuss doing a joint publication without prior notification of the boards. It’s taken 15 years to get back on track.

The EPA says that ERMI is for research purposes only, and not for air sampling in homes and businesses.

Like Ed Light’s air sampler, Don’s air sampler is also rusting in his basement.

In North America, the Allied Industry Partners group (comprised of 9 associations) and started during John Lapotaire’s IAQA Presidency is moving forward more rapidly. See

Internationally, the IEQ Global Alliance, see is slowly moving forward. Don is the current President.

Closing Thoughts:

  • Outdoor pollution is coming indoors. Worldwide, particulates are responsible for 2,000,000 deaths annually.
  • Climate change related IEQ issues.
  • HVAC in developing countries doesn’t always operate correctly.
  • Phthalates health effects. Ozone. Fake research. Particulates.

We had a very lively chat today among live listeners. This is what IAQRadio were thinking during today’s show:

  • I agree with Don on this! EXACTLY. Seems the AIHA opinion continually ignored by the typical mold inspectors. Phil Morey would agree…and didn’t we all learn from him first?
  • You’ll introduce more than 1 Stachybotrys spore during rebuild when you bring in the new building materials.
  • Primarily visual. sampling is secondary, if not tertiary. 9 of 10 of my projects “require” no samples.
  • Ask – is the contractor paid (and specified) to “clean” the air down to zero spores of “Stachy” or any spore for that matter? i doubt it. So how can you “Fail” based on a spore?
  • Spore counts are not always good. Look at percentage of indoor indicating species.
  • If visual inspections fail – don’t sample. Sample air and surface if you’re sure it’s clean.
  • See also: IAQA White Paper, NAMs in Clearance, 2014. Co-chairs, Larry Robertson and Jack Springston.
  • quote: “the result is not a clear, singular recommendation. Rather, it is now clear that site-specific circumstances drive the choice of either ON or OFF for NAMs during the PRV air-sampling process.”
  • A minimum of 20 minutes shutdown time needed before conducting air sampling. Timeframe needed for proper static conditions.
  • Quiescent for 24 hours before sampling.
  • I shut down HVAC and AFDs when I get there
  • nothing settles in only 20 mins.
  • VBNCviable, but not culturable
  • in the non-IH world, i.e., typical mold inspector, they think viable is “alive”, which is incorrect, but this causes a lot of confusion with those providing a “mold killing” product/service.
  • also, many think, incorrectly, that a culture shows all that is alive. it only results by growing a fraction of possible live spores
  • Culturable sampling is more appropriate for risk assessment of suspect medical correlation of the test results. Spore traps provide anecdotal information of a potential concern. Cultural sample provide more definitive results.
  • PCR would be even better
  • I would not say “more definitive”, they are too different to compare “definitive”. e.g.., definitive for those species actually grown. But not more definitive for likely spore concentration
  • PCR – unless of course you have species other than the base 36 available.
  • Microbial growth within the building envelop may be a combination of bacteria and/or fungal spores. Doesn’t occur often but you must consider it with water damage or intrusion cases. Definitely if there are sewage backups.
  • establishing a good sampling plan regardless of the environmental conditions.
  • Anytime that you have elevated levels that cannot be justified, split sampling should be done and send the samples to separate labs. All sampling equipment should be properly calibrated.
  • We (industry, those of us who actually understand) really need to do a similar paper FAQ no PCR/ERMI/HERTSMI. I (and others like e.g., Wei Tang) have a lot of discussion already available on these “methods”.
  • The problem is that Doctors are now putting faith in both PCR and ERMI/HERTSMI
  • They the docs, are COMPLETELY ignoring EPA warning! they ignore any discussion and critique of these scoring systems
  • “FAQs About Spore Trap Air Sampling for Mold for Direct Examination”, May 2019
  • Biggest Issue: Misinformation!
  • The public has too much bad information and cannot sort through properly.
  • We spend more time trying to debunk bad info than we do consulting on the correct info

Z-Man signing off