Air Date: 12-7-2018|Episode 526
Water has vapor pressure, spores don’t
Bill Vaughn, PhD, QEP, CIEC is President and Principal Scientist at Nauset Environmental Services, Inc. an air quality consulting firm on Cape Cod, MA. The firm has been involved in outdoor and indoor air quality since the late 1960s. The firm took its name from the Indian tribe that first met the pilgrims. In the late 1980s and early 1990s the firm was measuring vapors in soil and at spill sites and could measure vapors indoors with greater sensitivity than others.
Nuggets mined from the interview:
Déjà vu: Remembers a consulting projects in a 12 story building late 80s early 90s that suffered a water loss, visible multi colored mold turned out to be Asp/Pen species which took colors from environment and diet.
Déjà vu 2: Remembered “BIOS detector” a handheld spinning fan that impacted air onto petri dishes.
Radio Joe: What is the percentage breakdown of your workload?
Bill Vaughn: Business breakout is 70%-75% mold, 10% asbestos, 10% radon, balance general air quality issues and expert witness.
Radio Joe: Why and how did you develop your own sampling method?
Bill Vaughn: I became aware of the IICRC S-520 in 2003 and the 3 fungal conditions mentioned therein. The document stated that remediators should clean settled spores (Condition 2) and cross contamination from Condition 3 (active growth areas). With my physics background I knew that if you can’t see settled spores how can the areas being investigated be accurately characterized? If tape lifts and wipe samples were to be used best practices suggested that over 10% of surfaces areas would need to be sampled which was impractical.
How can you tell they are there if you can’t see em? Why not take a fan to get settled spores in air and capture on a spore trap and then compare? I found in Condition 1 areas there was little difference between quiet and disturbed samples. A big increase of 10 fold or more convinced me that there was settled spore contamination. The sampling on our first project in Martha’s Vineyard showed some areas had little difference other areas increased factor of 20X and more. The remediator needed to focus time and efforts on the high areas and effectively clean them.
Radio Joe: Why bother sampling why not treat the area as if it was contaminates?
Bill Vaughn: We help decide where the remediation efforts should be focused. When this is obvious we use our method to demonstrate effectiveness of remediation. In the Martha’s Vineyard project the home had quite a few rooms, we scattered our sampling over 4 areas and found 2 elevated requiring additional effort. When there are budgetary constraints and or insurance policy limits we help focus on areas that need attention and define conditions in advance, provide the guidance based on S-520 and if needed come back afterwards to provide post remediation verification.
Radio Joe: How often do you get called back to provide Post Remediation Verification?
Bill Vaugh: Very often, the remediators who follow S-520 commonly refer us.
Radio Joe: Did you need to refine or fine tune your method?
Bill Vaughn: Yes, in a basement situation where we were hired to confirm cleanliness we came in with small leaf blower, white glove clean, found elevated spores, after re-cleaning and use of leaf blower we determined that the leaf blower was blowing drafts under sill plates into areas which couldn’t be cleaned. We “backed-off” to using 12” house fans, which is rational because this is a size commonly used by homeowners. The fans are set on high speed and swept back and forth over horizontal surfaces, shelves, etc. to cause the disturbance. The fans kick up big particles, so we delay sampling for approximately 5 minutes and use a Cyclex D spore trap. I selected the Cyclex D because it had the smallest cut off points of spore traps at the time I purchased it. I was concerned about occupant inhalation risk inhalation is the scientific reason for characterizing the space by the smallest particles. [The Cyclex D uses a greased slide bends air and centrifugal force captures smaller sizes, 1 micron or lower particles.]
Radio Joe: How long are you running the sample and what is the flow?
Bill Vaughn: The Cyclex D- runs at 20 liter per minute flow. We run it for10 minutes. We encounter very little overloading at 200 liters air sampled.
Radio Joe: How many samples taken and how are locations chosen?
Bill Vaughn: Focusing on finding cross contamination or active growth in an inaccessible area we often take one sample in an open room up to 1,500 square feet. When the overall area is sectioned-off, there are different finishes and/or moisture impact we’ll take samples in multiple areas. Citing a project where he was called in to perform PRV clearance on a project with a large basement containing: a large finished area, bedrooms and a pool room. He decided to take 6 samples 3 pairs, found major settled spore contamination in a finished area that was gutted. Disturbed air samples were 15-20X higher than undisturbed. He recommended that the remediator to perform additional remedial work. We have also done pre remediation samples in occupied spaces.
Anomaly in sample results: A lab knowing that he does paired samples questioned whether a sample had been mislabeled when a disturbed sample came in lower than the quiet sample? According to Bill, this indicated that that the remediator did a good job because the makeup air being drawn from the remediated area and blown into the room was cleaner than the air in the room.
Bill Vaughn: When tenants complain about mold or irritation in their apartment, due to budgetary concerns he conducts worst case scenario sampling where only disturbed sampling is done to stir up maximum inhalable particulate. In 85%-95% of these complaints about mold in a space where there is no visible evidence, the sample results parallel what quiet samples would be in a clean space. Complaints are psychological or the result of disgruntlement. He always accepts tenant complaints as valid and uses moisture meters, thermos-hygrometer, to survey the areas the tenants highlight. Statistically In 90%+ of these situations no elevated spore levels are found.
Radio Joe: How do you handle assessment of mechanical systems and ductwork?
Bill Vaughn: Basically if there is suspicion of fungal contamination and the client wants some measurement, we measure in front of a duct while the fan is off and measure at a supply duct after the system is turned on. Fan velocity in ducts generally doesn’t pick up settled spores and we rarely see a difference unless there is contamination on coils or where humidification takes place. Duct velocity isn’t the same as our active handheld fan being swept around. If HVAC was running during Condition 3 (active fungal growth), we recommend the system be sealed off and the system be cleaned according to the NADCA procedure.
Radio Joe: What clearance criteria do you require?
Bill Vaughn: I’ve struggled with it. I’ve attended several IAQA annual meetings, seen presentations and counts categorized as indicating: a problem home, a medical condition, or irritation complaints and looked at the literature pattern. As we see health or irritation complaints seem to increase when counts of 1,000-2,000 per cubic meter or more are recorded and fewer complaints below we decided that our clearance criteria is 1,000 Asp/Pen per cubic meter or less. Asp/Pen are the primary molds that grow indoors. As some people are more sensitive, after discussion with an allergist whose patients were at near 500 per cubic meter or lower, we selected a guideline of 500 or lower for sensitized people. We call these our informal guideline because we know there aren’t any standards.
We also look for the scope of work to be complete, adequate cleaning and absence of odor. In addition, we use moisture meter on subflooring, sill plates and framing and will recommend additional drying when needed? This criteria is totally separate than mold issues.
Radio Joe: What about indicator species like Stachybotrys and Chaetomium?
Bill Vaughn: In New England when there is dampness Asp/Pen are the primary colonizers. Stachy is a slime mold; with ongoing or recently discovered leaks the surface tension of water holds spores in place. It’s only when the colony dries out that Stachy spores go into the air. I once took an outdoor control sample and got 2 Stachy spores in outdoor air. That convinced me that a couple of Stachy spores aren’t necessarily a problem. At <500-1,000 Asp/Pen spores per cubic meter we are satisfied. In situations where there is more extended wetness, we do look at individual spore counts. When 1-9 Stachy are found prior to remediation that’s not a major contamination. This is cleaned down to non-detectable or only 1-2 absolute spore counts. A condo project we were involved in had spore counts of Stachy above 500-1,000 and required significant attention; we were in on the baseline for that one. I’m not petrified and don’t react to small counts of Stachy spores because they are out there, I concentrate on Pen/Asp and bring Stachy down to single digits in the raw count.
Radio Joe: Describe air polishing?
Bill Vaughn: When mold remediators see visible fungal contamination they remove it. In reality remediators have been ignoring Condition 2 for years because they can’t visualize it. There are lots of Condition 2 settled spores. In order to determine if an area has settled spores you need to get them into the air and sample for them. Spores are particles they aren’t like water vapor. There’s a sidebar to my article in the IICRC Journal titled “Air scrubbers aren’t dehumidifiers so what?” After 5-8 hours most airborne particles settle out. So after spores settle out, air scrubbers are no longer really cleaning the air. Some people say run air scrubbers for 48-72 hours and they’ll clean. Air scrubbers aren’t effective after the first few hours. Periodic use of a leaf blower to create allot of turbulence in area being remediated, along with running multiple oscillating fans, drives spores into the air where air scrubbers can process spore laden air. By shifting and relocating air scrubbers and oscillating fans and periodically leaf blowing we’re getting all the spores suspended and getting really good results. You must dislodge spores from joists and corners. As spores settle both to the sides and behind the air movement devices they must be moved and re-orientated for best results. Water has vapor pressure and mold spores don’t, so dehumidifiers continue to work overtime and air scrubbers don’t.
Radio Joe: Have you seen differences between AFDs operated as air scrubbers versus negative air machines in removal of spores?
Bill Vaughn: Neither application removes spores unless you kick them into the air. Once you’re done with remediation, shut things down, turn off equipment and operate AFDs in air scrubber mode so that the room is under same air pressure as it will be when occupants are in the room. An air scrubber running isn’t typical of occupancy. Remember, when a negative air machine is running you are drawing air from areas you weren’t contracted to clean which complicates verification process. During remediation, use oscillating fans and a leaf blower to put spores in the air for removal. Then shut down air scrubber for 8-12 hours to make room representative of occupied space after removal of containment immediately prior to PRV.
Radio Joe: Any tips for listeners on assessment or remediation?
Bill Vaughn: Think about physics, water vapor goes into the air with the assistance of vapor pressure; particles don’t go into the air on their own. I got burned years ago taking wall cavity samples for mold and learned that debris messes with wall cavity samples. We now deal with viable spores in wall cavities in a similar manner to the way we sample accessible areas. It is important to gather what is capable of growing on a filter sampling cassette so while sampling we thump on surrounding drywall with a rubber mallet and then culture what is found on the filter. We select stud bays with the highest moisture reading for sampling and compare that to a control of a dry cavity. Spores within a wall cavity won’t get out without disturbance. We characterize what is in the wall, in comparison to a dry control spot. I use a polycarbonate cassette with .4 pore size, which is washed and have the analysis done as an air sample and expressed in CFUs.
Radio Joe: The IAQA/IESO Residential Mold Standard work has been moved over to ASHRAE. I know that you have been involved in the work, please provide a status report for our listeners.
Bill Vaughn: We’ve been working on it for a hell of a long time. It’s been almost 8 years since first meeting. The goal is to create Initial Residential Mold Assessment Standard, guidance on the things you need to look for and evaluate when you come into a home. Many inspectors are inexperienced physically, biologically and about the role of moisture on microbiology. The document has been stalled for 7-8 months due to the merger and transition between IAQA and ASHRE. Efforts on the document are now under the auspices of ASHRAE who has a different and more stringent requirement for wording due to their engineers. We are working to understand what is acceptable to both ASHRAE and to the writing group. Meetings are scheduled to resume in May. A decision may be made to publish a guidance document instead of a standard. Assessors need to be able to discern between cosmetic stuff and what’s important. Assessors also need to maintain their independence.
Radio Joe: I recently attended the Northeast Energy and IAQ Conference in Maine where there was a healthy debate over whether sampling should or shouldn’t be done. I suppose you are an advocate of sampling, how would you address the naysayers who say that the sampling money would be better spent on waterproofing or remediation?
Bill Vaughn: We avoid sampling when moisture damage, odor and fungal contamination is visible. If you see mold you don’t need to sample, the mold needs to be removed. We develop the operating protocol for remediation. Our sampling must answer a question. Are there elevated levels of settled spores? We use and advocate hypothesis driven sampling where samples are taken to address the hypothesis. We don’t just take samples.
Radio Joe: Do you see anything hot button IEQ issues on the horizon?
Bill Vaughn: Not really, stay attune to what comes out of research on issues such as fiberglass or cellulose fibers.
Radio Joe: We always give our guests the last word, is there anything you would like to add?
Bill Vaughn: Be open minded. Be aware of the physical and biological possibilities. Look at our website Nauset Environmental www.nausetenvironmental.com where you’ll find examples of our reports and our air polishing protocols. You can dry the air with extended use of a dehumidifier, you can’t clean the air with extended use of an air scrubber.
Today’s Music: “Growing Mold” by the Radioactive Chickenheads YouTube
Z-Man signing off
Now for this week’s IAQRadio trivia question:
According to the ANSI-IICRC S520 Standard and Reference Guide for professional mold remediation what are the definitions for Conditions 1, 2 &3?
Condition 1 (normal ecology) – may have settled spores, fungal fragments or traces of actual growth whose identity, location and quantity is reflective of a normal fungal ecology for an indoor environment.
Condition 2 (settled spores) – an indoor environment which is primarily contaminated with settled spores that were dispersed directly or indirectly from a Condition 3 area, and which may have traces of actual growth.
Condition 3 (actual growth) – an indoor environment contaminated with the presence of actual growth and associated spores. Actual growth includes growth that is active or dormant, visible or hidden.