Using Vacuum Cassettes or Spore Traps to Collect Mold or Particle Dust Samples
How to do it &
Guide to Good Dust Sampling Practices
VACUUM CASSETTE FILTER SAMPLE TESTS for DUST / MOLD - CONTENTS: Field testing vacuum cassettes to collect building dust as a screen for toxic or allergenic mold contamination indoors. Guide to use of vacuum cassettes to screen building soft surfaces, furniture, carpeting. Guide to use of vacuum cassettes to collect multiple dust samples in buildings
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Vacuum cassette test methods for building dust or mold:
This article explains the advantages and shortcomings of using vacuum cassettes or spore traps to collect mold test samples (or other dust or particle samples) from indoor surfaces such as carpets, couches, or multiple hard surface dust samples
. In this article series discuss the validity of nearly all of the popular mold testing methods currently in use, pointing out the strengths and weakness of each approach to mold sampling in the indoor environment, beginning with air sampling for airborne mold levels indoors.
A Guide to Using Vacuum Samples for Screen Buildings for Toxic Mold
15th Annual North Carolina/South Carolina
Environmental Information Association Technical Conference
Myrtle Beach, SC
Daniel Friedman 23 September 2005, Updated 4/14/2009 & 10/5/2012
A collection canister is connected to an air or vacuum pump which is used to
draw particles onto a filter-surface or into a special collection container.
A collection device, slide, cassette, or tape are used with a calibrated air pump to collect surface particles.
The lab prepares a slide from the cassette (of the types below) or if an MCE filter cassette was used to collect particles, the lab clears the filter onto a microscope slide, washes the filter onto a
microscope slide, or uses another method to transfer particles for examination
by microscope for preparation by culture.
Our MOLD INFORMATION CENTER includes more broad discussions of the overall approach to building investigation, as do many expert references cited at that web. For a more
comprehensive collection information about mold test methods see INDOOR AIR QUALITY METHODS COMPARED.
For more on "mold classes" (Cosmetic mold vs. allergenic mold vs. toxic or pathogenic mold) see MOLD CLASSES, HAZARD LEVELS and more references such as a Mold Action Guide are at the end of this document.
Using a simple portable pump calibrated to a known flow rate allows rough estimation of particle density per square inch of surface tested if that analysis is needed.
People using this approach may make use of a disposable paper square template that defines a precise surface area to be vacuumed (photo above left). In our opinion a precise quantitative approach to surface vacuuming is silly because there is normally large particle variation over building surfaces for many reasons. But the approach is useful to screen for high levels of particular particles (such as mold spores, animal dander, insect allergens).
Our photo (left) shows five vacuum test areas on a hallway carpet during a study conducted by the author to examine the variation in particle deposition by foot traffic in a residential hallway.
Our hypothesis was that more outside dirt and debris could always be found in the center of the main path of foot traffic even though that area also received more aggressive vacuum cleaning than the hallway sides. We have tested carpeting before and after various types of cleaning and after suffering various types of contamination.
Surface vacuuming for mold
We emphasize that in this article we are discussing surface vacuuming to collect particles from an exposed surface onto which the vacuum device and collector can be placed directly.
This is an effective and useful particle or mold sampling method.
We are not referring building wall or ceiling cavity vacuuming methods that attempt to draw air and particles from the building cavity through a punctured opening and tube into a collecting device - an approach that our test found was ineffective.
Vacuum samples can be useful for testing soft goods (clothing, bedding,
curtains, carpets) for high levels of contaminated
spores in a qualitative approach. We particularly like vacuuming a number of
surfaces in an area using a single collection device as a less-costly way to
make a more confident inspection of the level of contamination by moldy dust in
buildings with a known problem.
We also use this method as part of a mold
clearance inspection to evaluate the thoroughness of both the containment
system and the general cleaning effort. For example we may collect a sample of
vacuumed surface dust from 10 different surfaces in 5 rooms on a floor of a
home, forming a more broad screen for moldy dust than single tape lifts of
We've found wide variety in levels of mold found growing in or on carpets,
depending on a number of variables including even the level of other dirt
present in the carpeting. Some experts question this measure.
Carpet vacuuming for mold is interesting as a
pre and post remediation baseline data source for areas out of the
remediation/containment area, but for any carpet this method quickly overloads
a particle sampler.
The Burkard personal air sampler (photo at left) can also be used to vacuum particles from surfaces provided that a strong air flow is not required to lift the particles from the surface (this device pumps at 10 lpm).
Shortcomings of surface and carpet vacuuming for mold
Vacuuming will not collect
identifying structural components of mold as well as tape and will almost
certainly damage or destroy the structures which it collects, imposing
some limits on identification
Vacuuming will not collect
all of the material on a hard surface (which tape handles well). Particles
which are easily lifted by the airflow into the canister will be
over-represented compared with sticky particles which are adhered to the
This problem is particularly sensitive to the flow rate (LPM)
used. A low-flow rate (1LPM) avoids a sample overload problem (too many
particles, can't read the sample) but may fail to collect or under-collect
certain particles. A high flow rate improves particle pick-up but then
limits the number of sample sites (increasing test cost) in order to avoid
sample overload. We suspect that no vacuum method we have tested could
reliably pull mold or debris reliably from deep inside a heavy upholstered
Carpet vacuums and some
furniture or drapery vacuums will either be overloaded or restricted to
culture (to which we have already objected).
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Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home",
U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [Copy on file at /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [Copy on file as /sickhouse/EPA_Moho_Guia_sp.pdf - en Espanol
"IgG Food Allergy Testing by ELISA/EIA, What do they really tell us?" Sheryl B. Miller, MT (ASCP), PhD, Clinical Laboratory Director, Bastyr University Natural Health Clinic - ELISA testing accuracy: Here is an example of Miller's critique of ELISA
http://www.betterhealthusa.com/public/282.cfm - Townsend Letter for Doctors and Patients
The critique included in that article raises compelling questions about IgG testing assays, which prompts our interest in actually screening for the presence of high levels of particles that could carry allergens - dog dander or cat dander in the case at hand.
http://www.tldp.com/issue/174/IgG%20Food%20Allergy.html contains similar criticism in another venue but interestingly by the same author, Sheryl Miller. Sheryl Miller, MT (ASCP), PhD, is an Immunologist and Associate Professor of Basic and Medical Sciences at Bastyr University in Bothell, Washington. She is also the Laboratory Director of the Bastyr Natural Health Clinic Laboratory.
Allergens: Testing for the level of exposure to animal allergens is discussed at http://www.animalhealthchannel.com/animalallergy/diagnosis.shtml (lab animal exposure study is interesting because it involves a higher exposure level in some cases
Allergens: WebMD discusses allergy tests for humans at webmd.com/allergies/allergy-tests
Atlas of Clinical Fungi, 2nd Ed., GS deHoog, J Guarro, J Gene, & MJ Figueras, Centraalbureau voor Schimmelcultures, Universitat Rovira I Virgili, 2000, ISBN 90-70351-43-9 (you can buy this book at Amazon) - The Atlas of Clinical Fungi is also available on CD ROM
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
"Disease Prevention in Home Vegetable Gardens,"
Department of Plant Microbiology and Pathology,
Department of Horticulture, University of Missouri Extension - extension.missouri.edu/publications/DisplayPub.aspx?P=G6202
Fifth Kingdom, Bryce Kendrick, ISBN13: 9781585100224, is available from the InspectAPedia online bookstore - we recommend the CD-ROM version of this book. This 3rd/edition is a compact but comprehensive encyclopedia of all things mycological. Every aspect of the fungi, from aflatoxin to zppspores, with an accessible blend of verve and wit. The 24 chapters are filled with up-to-date information of classification, yeast, lichens, spore dispersal, allergies, ecology, genetics, plant pathology, predatory fungi, biological control, mutualistic symbioses with animals and plants, fungi as food, food spoilage and mycotoxins.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.