Perception Environmental, Inc.

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Air Sampling for Mold

Considering Bioaerosol (Mold) Sampling

Bioaerosol sampling (air sampling for mold or other biological contaminants) usually is not necessary to determine remediation effectiveness.  In fact, bioaerosol sampling may be less effective at determining the success of remediation than visual and sensory surveys of the area.

Although sampling may be of some help in judging remediation effectiveness, remember that a negative sampling report must not be used in place of a visual survey.  Factors such as barometric pressure, inside and outside temperatures, activity levels, and humidity may dramatically reduce or increase the spore levels within a building.  Air sampling for mold provides information on what was in the air only for the moment when the sampling occurred.  It is important, therefore, that sampling not replace visual inspection.

If the “Mold Inspector” tells you to determine if there is a mold problem in your house we have to collect air samples from the outdoors as a control and then indoor samples to determine your mold problem in your house, its junk science! Riddle me this batman…What if it’s raining? Mold spores are high during this time. Will lower counts indoors then depict a clean environment?

How about taken outdoor samples when a blanket of snow is on the ground and temperatures are freezing. The home inspector or “mold inspector” will tell you that the indoor spores are higher and tell you that the walls will have to be opened to conduct exploratory remediation. Hey “mold inspector” at what temperature do molds no longer survive?

The real good “mold inspectors” provide laboratory data that shows fancy graphs and comparison data that validates their sampling. NOT! I’m being facetious! A good Hygienist will conduct a visual assessment with direct reading instrumentation to support his findings with no air sampling needed.

 

There are times when air sampling is required but not during an initial assessment.

 


Mold Spore Count Reference Guide©

Currently and ongoing for years, arguments on how to set a standard for mold spore levels in homes has been considered.  Because mold spore species and levels differ from state to state and the immune tolerance levels of each individual vary, regulatory agencies have not been able to agree.  So a comparison to an outdoor air sample has been the current industry standard.   Why? Because every time you open a door or window mold spores are entering into a home.  It is not a perfect method and can lead to false positives; however factors such as barometric pressure, inside and outside temperatures, activity levels, and humidity may dramatically reduce or increase the spore levels within a building. For this mold spore reference guide© use the spore/m3 number and not the raw count for each species when you interpret a Microbial Air Sample Report from the Laboratory.  There are exceptions at every level.  False positives can be caused by a number of different issues.  Normal everyday life examples are dust and dirt on fan blades or other surfaces of the home, something in a garbage can or household pets that have been playing outside. When a general home inspection or normal activity is ongoing at the same time during air sampling collection it can inadvertently raise the spore counts. This can happen if an interior attic access is opened, an exterior door, dirty shoes from just entering the house or the air conditioning (A/C) filter is removed from the return before the air sample is performed.  In addition to elevated interior relative humidity (RH) levels and/or moist or damp building materials.

 

The following mold spore ranges are in my opinion and are based on hundreds of samples collected by me in the Chicago land vicinity during Mold assessments.

Additionally, Air-O-Cell manufacturer has provided a guidance document that identifies a clean interior verses a contaminated interior.

 

 

0-50 spores - These are only trace levels and are not an issue. Even Stachybotrys is not considered an issue at these levels if the sample does not also contain water markers like Chaetomium and Fusarium or high levels of Penicillium/Aspergillus.

 

50-200 spores - These are still very low levels. Stachybotrys and Memnoniella are just about the only species that are considered an issue at this level. Why?  Because they don't belong in an interior functional living space. These types of mold spores say there is a water intrusion problem for some time. 

 

200-500 spores - Up to this point, the most common species (Penicillium/Aspergillus, Cladosporium and Curvularia) are still not an issue and are in the normal range.

 

500-1500 spores - Sometimes the Penicillium/Aspergillus & Cladosporium levels are in this range and there is not an issue that needs to be remediated. If no water intrusion or mold issue is found during the inspection, these levels can be caused by every day normal life in an enclosed environment.

 

1500-3000 spores - This is where the grey area begins. When levels reach this point there may be an issue that needs to be addressed unless there is a corresponding number in the outdoor sample. If no water intrusion, RH or visible mold issue are identified during the inspection these levels can be achieved by a dusty home or A/C system.

 

3000-10,000 spores - Unless there is a corresponding number in the outdoor sample, this is the point where an additional inspection. If a mold spore source has been identified, then clean up of that area is needed. If there was no water intrusion or mold issue found, the home may need to be cleaned and the duct system should be evaluated.

 

10,000-25,000 spores - Unless there is an equivalent number in the outdoor sample, a mold spore source has usually been identified and remediation of the area is needed. If there is no water intrusion or mold issue found, the duct system may need to be cleaned and/or a general "Spring Cleaning" of the home.

 

25,000-75,000+ spores - When spore levels are at this point, a mold issue will be easy to identify. Clean up will be required and should be performed by a Professional Mold Remediator.

 

75,000-1,000,000+ spores - When spore levels are at this point a mold issue will be evident. Remediation will be required and needs to be performed by a Professional Mold Remediator.

 

 

 

  Call me at 815.341.0213

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