Joe C. Spurgeon, Ph.D. – The Collection and Interpretation of Indoor Mold Samples – A Comparison of Methods

Air Date: 7-10-2015|Episode 375

This week IAQ Radio welcomes author, consultant, industrial hygienist and accomplished industry professional Joe Spurgeon, Ph.D. We are going to discuss Dr. Spurgeon’s new book “The Collection and Interpretation of Indoor Mold Samples – A comparison of methods” and other topics related to mold inspection, sampling, and interpretation of data…

Full Description:

This week IAQ Radio welcomes author, consultant, industrial hygienist and accomplished industry professional Joe Spurgeon, Ph.D. We are going to discuss Dr. Spurgeon’s new book “The Collection and Interpretation of Indoor Mold Samples – A comparison of methods” and other topics related to mold inspection, sampling, and interpretation of data. In his new book Dr. Spurgeon discusses his concern that “none of the sampling methods, or data interpretation methods, we use in the mold industry have ever been validated”. The book goes into detail on the importance of sampling to answer specific questions and gives you examples of what questions to ask. Dr. Spurgeon states that “the selection of the sampling method and data interpretation method affects the ability of the IEP to correctly interpret the sample results and assess condition. One objective of this manual is to improve the investigator’s ability to compare the utility of sampling and data-interpretation methods based on objective criteria.”

Dr. Spurgeon has a multidisciplinary doctorate degree in Analytical Chemistry and Environmental Health from the University of Pittsburgh; and was a Certified Industrial Hygienist from 1993 – 2013. His career has included working as a research chemist on the NBS Lead-Paint Poisoning Program, directing the FAA’s Combustion Toxicology Laboratory, performing Health Assessments for CDC/ATSDR, implementing US EPA’s Laboratory Exposure Assessment Project, and working as a consultant specializing in microbial indoor air quality for US PHS. He has performed over 4,000 residential and commercial investigations involving water intrusions and microbial contaminants; has taught courses on mold investigations, sampling, and data interpretation methods; and has served as an expert witness in numerous mold cases. Additional articles from Dr. Spurgeon aree available at LEARN MORE this week with Joe Spurgeon, PhD on IAQ Radio!

Z-Man’s Blog:

Facts trump opinion

Dr. Joe Spurgeon, PhD author of the book The Collection and Interpretation of Indoor Mold Samples – A Comparison of Methods has a multidisciplinary background in chemistry, public health and industrial hygiene. He has consulted on microbial indoor air quality for the US public health service and performed over 4,000 investigations in water damaged buildings. He became interested in the health effects of mold in the 1980s when as a builder/contractor he was exposed to moldy drywall and was hospitalized for four weeks with a serious lung infection (Aspergilloma).

Nuggets mined from today’s episode:

  • Based upon positive reviews on his presentations on mold sampling at IAQA National Workshop; he decided to write book and appeal to a wider audience and start a discussion on sampling and data interpretation.
  • None of the sampling or data interpretation methods currently being used have been validated.
  • How would a sampling method be validated? Technically NIOSH lab methods such as: sample times, media, flow rates, and reproducible lab methods are verified. Sampling methods should also be practical and produce usable and actionable information allowing the indoor environmental consultant to answer the homeowners question “is the home OK or does it have a problem”?
  • Exposure assessments have the objective of: determine if the structure is fungal contaminated; or do occupants have a significant exposure?  These are two different questions. It takes different sampling and data interpretation methods to address each question. What are we trying to determine – building contamination, occupant exposure or both?
  • Industrial hygienists use validated methods primarily and mold inspectors do not. The IEQ industry hasn’t required sampling validation to be done. The need for validation is widely unrecognized, perhaps due to the lack of a perceived need for change.

Case study. A torrential and violent rainstorm caused water intrusion in a hospital. Dr. Spurgeon was responsible for determining what needed to be done, where it needed to be done and in what order? Data interpretation was critically important. The common reference method of comparing indoor fungal concentrations to outdoor concentrations wasn’t applicable or useful because the air in the hospital was triple HEPA filtered air which should have no relationship to outdoor air. Outdoor samples varied by day and time and time of day and weren’t useful.  Rather than comparing outside air to air inside the hospital he used a control method where he first attempted to categorize the hospitable into: uncontaminated areas and potentially contaminated areas. By comparing indicator molds from indoor sampling he was able to validate his findings.


Reference method, compares indoor to outdoor and is often not the best method to use. There are 6+ published peer reviews studies that demonstrate indoor outdoor comparisons are not very effective. Dr. Dan Bridge, PhD (Rimkus Consulting) conducted a broad study collecting indoor and outdoor samples. [422 samples were collected, in 108 houses, in 23 cities, in 9 states, and over 2 years]. When indoor samples were compared to the outdoor samples little correlation was demonstrated and no valuable data was provided. However, when indoor samples were compared in rank order usable, actionable data was obtained which also enabled future samples to be interpreted.

Fungal contamination is sometimes built-in. Two studies one in US and one in Europe demonstrated that spores from indicator molds are already in “postconsumer use” papers used to make drywall, simply add water and they will grow.

Control method used in commercial buildings, differentiates between normal background and contaminated areas. Mentioned in the Bioaerosols manual (1999) control samples should always be pulled in commercial buildings for present and future data comparison. Dr. Spurgeon also recommends pulling control samples in residential buildings. Concentrations are hard to compare, while comparing distributions of concentrations makes sense.

Data base method while not used in IAQ it is used in industrial hygiene comparing distribution of concentration rather than concentrations and is a more sophisticated data-interpretation method. For example: enter the Asp/Pen sampling results from the last 50 inspections on a spread sheet in rank order (from lowest to highest concentration). Compare current results to range of concentrations; when current results are in the 50% percentile that’s an average concentration if in the 95% percentile the concentration is elevated.

  • Asp/Pen is most frequently detected indicator spore in contaminated indoor environments. He finds Asp/Pen in 90% of contaminated environment in airborne spores versus Stachy which is found in only 5%-10%.

 3 conditions

“Typical condition”, less than 1,000 spores per cubic meter, break point decision criteria assessment, less than ½ limit assessment is acceptable, greater than 1,000 assessment greater uncertain, and higher is unacceptable.  Potentially Contaminated and Contaminated Condition.

Sampling is one tool in the IEP’s tool box, others include: visible signs of moisture, incident reports of water damage, occupant health survey and sample results. Some sampling is a critical part of all mold investigations.

  • Visible inspection while necessary is prone to false negatives. Sample collection is more reliable, facts trump opinion. Sampling will confirm presence of hidden mold sources inside walls under carpet.                 Samples should always be taken when here are adverse health effects, when ordered by a physician, for immune compromised people and in legal cases.
  • Filter sampling is widely used in industrial hygiene and should be used more often in IEQ inspections.                                                                                                    Filter versus spore traps? Bi-Air cassettes do the function of both at same time collecting duplicate samples on 25mm filter. The samples can be analyzed by microscopy for indicator spores, by culturing or with QPCR. The first level of filter cassette analysis is similar to asbestos, the filter is dissolved in acetone and the sample analyzed.
  • It’s false analysis to compare 3,000 Asp/Pen outdoors to 1,000 Asp/Pen indoors, unless comparing actual species/ IEP’s should urge labs to differentiate between types of Asp/Pen spores (rough versus smooth, for example). When smooth Asp/Pen outdoors and rough Asp/Pen are found indoors it’s obvious they aren’t from the same mold colony and indicate an indoor source.
  • Typical spore trap slit impactor underestimates the amount of spores in the air. Commonly used cassettes collect only 50% of Asp/Pen spores in air and only 5% of Chaetomium spores.
  • Spore traps are better than culturable samplers, as the limit of detection is less important than maximum concentration. Maximum reportable concentration is the more important parameter.
  • It’s almost impossible to investigate the association between airborne mold and adverse health effects because the quality of short-term data available to investigators is so poor.
  • Fungal fragments are important. But first things first, if we can’t measure the spores let’s come up with a method to do that first.
  • Investigator must understand the objective of what he is trying to accomplish, determine building contamination or occupant exposure. Long-term sample times as defined by NIOSH are 1 hour or more. Dr. Spurgeon uses sample times of 3-8 hours in hospitals. Slit-impaction cassettes are NOT INAPPROPRIATE for assessing building contamination, but they may be INAPPROPRIATEfor assessing occupant exposure.

Carpet sampling strategy divides carpet into 3 groups: center of room (clean), under windows and sliding glass doors (potentially contaminated) and carpets with visible contamination. Sample all 3 groups with various methods and look at the data on weight and area basis to determine which combination of sampling method and data collection allowed carpets to be statistically separated into the 3 groups. Recommends to his clients that they do nothing with clean carpet, clean potentially contaminated carpet and discard visibly contaminated.

Open Faced Fixed Area works the best. Open faced 25mm cassette held against carpet for 5 seconds, x 20 different areas, as CFU’s per 100 cm of carpet or QPCR allows carpet to be categorized into the 3 categories.

The conversation. Wants people to first read his book and then have a robust and honest discussion on sampling and data interpretation methods. What works and what doesn’t? Does the test method have utility? Do indoor and outdoor comparisons have utility? Do numerical guidelines have utility? It’s hard to believe that when an inspector reviews a report full of numbers that they don’t use numerical guidelines to interpret the report. The guidelines are in their heads, not written down so they can’t assess utility and validity.

Destructive testing combined with visual inspection can result in false negatives. For example, 3 industrial hygienists agreed they were looking at perfectly clean drywall, when swabbed and cultured the drywall had over >1,000,000 CFUs per square inch of mold. Why collect a wall cavity sample, or any sample, that can’t be interpreted? Only 2 samplers and sampler probe combinations worked and collected interpretable samples from interstitial wall cavities.

  • Wall Check Sampling is as good or better than borescope and destructive testing.
  • Quiescent versus aggressive sampling in dry wall cavities? Air sampling within damp/wet air cavities is difficult so he recommends aggressive sampling in all wall cavities.

Data base methods

  • Dr. Spurgeon compares indoor samples to the control sample, then his robust sample data base of indoor samples.

 Soft surface sampling

  • “Differential sampling”. A bevel tipped cassette brushed across upholstery picks up mold spores on surfaces. An open faced cassette held firmly on cushions draws from both the surface and deep within. Are the analysis results the same or different? Differing results with Clad lying on surface and Asp/Pen deep within the couch indicates deep seated mold contamination which can’t be cleaned while surface mold can be cleaned.

 Surface mold and occupant exposure,

  • Surface mold samples and airborne samples collected in the same place at same time can provide a linear plot indicating that surface mold was affecting occupant exposure and providing a rough estimate of amount of exposure.

 Is an item clean or contaminated?

  • Presents data ranges from samples collected from clean items.

 Microscopy versus QPCR?

  • Bi-Air cassettes take duplicate samples and attain good correlation coefficients, however a sample which had 10,000 spores/m3  CFUs Asp/Pen and was also analyzed with QPCR found no mold because the correct primers weren’t used, always do microscopy when using QPCR.

 As seen on TV

  • He did a fungal investigation in Erin Brockovich’s water damaged home and was seen on the “48 Hours” TV Show that chronicled the story.

The last word.

Dr. Spurgeon wants to get the conversation started. We need permission as an industry to discuss what works and what doesn’t work.

For more information on the mold sampling book or Bi-Air cassettes, Dr. Spurgeon can be reached at or

Z-Man signing off

Trivia: What home was Dr. Spurgeon inspecting when he was filmed back in 2001 on 48 hours?Answer: Brokovich