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Particle Levels vs Sampler Height Variations When Air Sampling for Mold MoldAPedia © Enter your search terms Submit search form   Search This Website - InspectAPedia.com

• How does air sampler height affect mold counts or mold sample results?
• Just how accurate and valid is air sampling for toxic mold testing?

This article discusses Mold or Airborne Particle Levels versus Air Sampler Height when testing for airborne mold. This document is a brief tutorial which provides information about the accuracy of and sources of errors in tests for the level of allergenic and toxic mold in residential buildings: Are spore counts valid? Are cultures and swab tests valid? These critical questions are discussed in this paper. Readers should also see Mold Spore Counts: are indoor fungal spore counts valid?, and for a more in-depth critique of popular mold testing methods than this tutorial see Mold Sampling Methods in the Indoor Environment © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Variation in Airborne Particle Levels due to Placement Height of Air Sampling Device

How much difference does it make whether the air sampling machine is placed on top of or underneath a mold-contaminated table? The photographs above show microphotographs of representative sections of an airborne particle sample trace in the same room in a building, with a single variation: the left hand photograph of a mold spore sample shows just a few fungal spores was collected with our sample placed on top of a basement pool table. The right hand photo of a mold spore trap sample shows a very high spore concentration in the same room, obtained when we placed our sampler on the floor below the (mold infected) pool table. In both samples we used passive methods.

Had we stirred room air (say by turning on a fan or waving a notebook, it is likely that these "under table" mold spores would have been distributed more uniformly in the building's indoor air.

Many IAQ consultants place their air sampler at about chest or head height in a building, presuming that will best represent the particles that will be inhaled by building occupants. This sounds reasonable except that mechanical disturbance of local indoor dust will cause enormous variation in the actual particle level at any given time and will probably make the particle distribution more uniform in the space.

How many mold reports document the details of sampling such as where mold was visible, where the sampler was placed, and what possible variations in airborne particle level might obtain depending on details of how the sample was collected? Almost never is this information considered, gathered, or reported by the hygienist or other mold investigator.

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

ACCURACY OF VARIOUS MOLD TEST METHODS
  Causes of Variation in Airborne Particle Levels
  Indoor vs. Outdoor Spore Counts
  Extent of Variation of Airborne Particle Counts
  Particle Levels vs Sampler Height
  Particle Levels vs Windows/Doors
  Particle Levels in Ducts
  Concentration Bursts of Mold Spores
  False Negative Results in Mold Tests
  Mold Culture Plate Test Errors
  Why Use Airborne Mold/Particle Sampling?
  Visual Inspection and History for Mold

Technical Reviewers & References

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material.

• Thanks to Susan Flappan, Flappan Consulting, moldetect.com, Overland Park KS, 913-402-1131, for contributing comments and some suggested text from ACGIH Bioaerosols: Assessment and Remediation 12/2006.
• Daniel Friedman - principal author/editor of the InspectAPedia ^TM Website
• Technical reviewers are invited to comment or ask questions - contact us

More expert information on this topic

More Information on Building Diagnostic Inspections and Repairs

• Mold Information Website Home Page
• Mold Classes: what types of cosmetic, allergenic, or toxic mold are a problem? Can mold be cleaned-up successfully?
• Toxic Mold, Allergenic Mold: How Much is Bad?
• Validity of Bulk Surface or Tape Sampling
• Validity of mold cultures and "home test kits"
• Validity of culture methods for toxic mold inspections
• What to look for in a toxic survey report or toxic mold test lab report
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