Mold testing using non-viable air sampling is commonplace, but what are these reports telling the consumer? The answer is, not much. In fact, these reports often create confusion especially when the inspector is unable to explain what the report means. If they could explain the meaning, generally the correct explanation would be, “it means nothing.”
Mold and mold spores are omnipresent; meaning they are always present, and depending upon the climate, winds, rain, temperature, dew point, and vegetation, mold spores can be present in high numbers at any given time. Taking an air sample is nothing more than a snapshot in time. There is little benefit in taking a single sample as conditions may be significantly different at another time or day.
Indoor Air Quality Testing
Non-viable air samples were never intended to be used to identify an indoor mold condition. Air sampling was designed to assist in targeting potential areas of concern in large spaces. If we are checking indoor air quality in a large office building, it may be beneficial to take bulk air samples in many different locations to identify areas of concern while saving time. These spaces may have air infiltration from the outside or have elevated moisture conditions which we need to investigate. Knowing where these target areas are could save considerable time/expense.
Simply, when we get a sample showing significantly higher readings of mold spores in a given location, we know this is a good place to evaluate further. Perhaps we found some water indicator mold spores in an area which do not show up in other areas or the spore counts were 10x higher on one side of the building than the other; these are indicators we need to look further. They are not conclusive evidence of a mold condition and in fact, there may not be a mold condition. Indoor mold is always related to a building related issue, so it tells us we need to look for leaks, air infiltration, poor ventilation or other building related obsolescence.
Non-Viable Air Sampling
Sadly, few “mold testers” understand the meaning of “non-viable” air sampling. Not all mold spores are “viable;” meaning, even if they were placed on a perfect substrate of food/moisture, less than 1% of mold spores will germinate. Think of it like seeding your lawn. If you have done it, you know only about 40% of the grass seed you bought will germinate even if you have the perfect temperature and moisture. Luckily, for humans, less than 1% of mold spores are capable of growth; otherwise, we may not be able to inhabit the earth. On any given day, we are exposed to millions of mold spores without knowing it. Can you imagine if 40% of those spores germinated and formed mold colonies?
When these spores enter our homes (less than 24 mold species are capable of growing indoors out of over 5 million species), and assuming we have the perfect substrate for them to settle upon, less than 1% have the capability to form mycelium/hyphae and to produce spores. Think of it this way; when you see a spore count of 36,000/m3, that is statistically less than 360 spores which are even capable of development in a perfect environment. 360 spores is simply not much to be overly concerned with.
What is the Perfect Environment for Mold Growth?
Do you see visible mold or has the mold tester advised you have a “perfect environment” for mold growth? The spores are irrelevant if there is not a perfect environment to support mold growth. Further, different mold species have different water activity requirements. Finding a few spores of stachybotrys is meaningless unless we have water activity over .95 (meaning wet). Stachybotrys, in the absence of water, has less than 0.01% of viability so finding 20 spores of stachybotrys in an air sample without finding a leak means there is a 0.002% likelihood of even the possibility of growth! This is hardly worth discussion or further evaluation. No one is going to pursue any endeavor with a 0.002% chance of success.
Fungal growth in buildings starts at a water activity (AW) near 0.8, but significant quantities of mycotoxins are not produced unless AW reaches 0.95 and then following a drying time whereby spores are liberated into the airstream (Note: pure water is 1.0 AW). Most spores are then only released with physical agitation (the reason we construct containments to isolate the workspace during remediation). In short, if the building material gets wet, and stays wet, we do not have a spore release. If the material gets wet and then dries, spores may be released following some type of physical agitation. In nature, this agitation may be winds, rain, or animal activity.
The Difference Between Transitory & Active Spores
Non-viable air sampling does not tell us (or the laboratory conducting the analysis) if the spores found in the sample are “transitory” or “active.” Mold spores and particulates build up a transitory presence over time in any location. Mold spores settle onto surfaces; they do not remain airborne very long. If a home has been vacant for a period of time or if the home is not very clean, these spores will settle on carpets, rugs, and on dust on the floor. When we enter the home, winds may follow us through the door, we may turn down the thermostat and get air circulating, we open doors which creates drafts and by walking across the floor, we kick-up these settled spores into the air.
Our initial entry alone may stir up hundreds/thousands of settled mold spores/particulates which we then collect in our air sample, but that does not mean we have “viable” mold spores which are capable of growth! Unfortunately, in their quest to sell “mold analysis” laboratories simply do not explain this to consumers and chances are the person you hired to conduct “mold testing” may have no knowledge of this; they sell mold testing.
Mold Sampling Conditions
For the most part, laboratory mold reports are worthless. They have no knowledge of the site conditions, the weather, the skill of the mold assessor/tester, the history of the structure, the efficiency of the HVAC system, the building condition, the occupancy/use or anything else necessary in determining if a mold condition is present yet they willingly pretend they do by issuing mold reports stating “ELEVATED CONCERN” and other such nonsense. The mold tester gives you the lab report showing “ELEVATED” and advises you to conduct further evaluation which means you should hire someone who knows something about mold. In short, you were ripped off.
Mold is a concern in Florida, and you should make sure the home you are buying does not have a mold issue. If there is cause for evaluation, hire a qualified mold assessor/building inspector who understands mycology as it relates to building science. If they start out offering air sampling, you know to keep looking.
William Chandler is a licensed Mold Assessor and Council Certified Indoor Environmental Consultant with Property360. We provide indoor air quality assessment, forensic moisture investigation, mold assessment and clearance testing throughout Jacksonville, Orlando, Green Cove Springs, Keystone Heights, Lake Butler, Lake City, Macclenny, and the surrounding areas in Florida. Our certified mold inspectors understand all the factors that affect indoor air quality and are experienced and knowledgeable in associative contaminants. Request your mold inspection today by contacting our team at (904) 503-9808.