Recent vs Old Building Dust: Definitions, Locations, Uses in Indoor Environmental Testing
At DUST SAMPLING PROCEDURE we discuss whether or not one should be testing for problem dust articles at all? So should we be collecting and testing building dust?
Probably not: If the building IAQ question is simply about mold identification, and you already see mold on indoor surfaces, NO mold testing is needed to just to confirm that mold is present in the building and that cleanup is needed
. Sure, it might be just cosmetic mold (seeCOSMETIC MOLD, RECOGNIZE ) but for small mold cleanup jobs testing is not normally appropriate.
Maybe yes: But if you need to identify the contents of dust, for example to help track down possible sources of building dust particles, or to screen for problem particles such as dust mite fecals, insect fragments, animal dander or hair, soot, fiberglass, etc., or if a large mold remediation project is planned, tests may be needed for project control.
SeeMOLD TEST vs. PROBLEM DIAGNOSIS
Dust sampling theory: usefulness & definitions of "old dust" and "recent dust" in buildings & where these are found
The following description of "old dust" and "recent dust" are my subjective opinion based on experience and are intended to supplement the building settled dust sampling method discussed at MOLD TEST KITS - how to collect settled dust from individual or multiple surfaces using clear adhesive tape as a means to characterize what particles have been in building air over time.
Definition, Location, & Usefulness of Collecting "old" building dust
Old dust represents particles settling out of building air a time period of weeks, months, years, or dust conditions before, or at the end of a recent demolition, renovation, or cleanup project.
Even after recent cleaning, old building dust can often be found in locations rarely cleaned such as horizontal trim over a door, on window muntins or blinds, under radiators, etc.
An old dust sample is useful to get an idea of the historically dominant particles present in a building and to screen for unusual particles that should not be there. The common dominant particles in most residential buildings are fabric fibers, skin cells, often starch granules (photo above left) and at lower levels, typical airborne mold, dust mite fecals and similar material.
Definition, Location, & Usefulness of Collecting "recent" building dust
Recent dust represents particles settling out of building air only recently, such as dust falling onto a surface that we know was recently cleaned completely.
While statistically less robust since it represents only a shorter time interval (typically days or weeks), recent dust can serve as a screen to look for evidence that problem particles remain in a building at actionable levels - or not.
Just how much time needs to elapse between building cleaning and the collection of a meaningful sample of recent building dust varies from hours to a month, depending on building materials, contents, occupancy, HVAC systems, cleanliness of adjoining areas and similar factors.
Key is to collect recent dust from a surface that we know (and perhaps confirmed by earlier sampling) was previously cleaned and very low in settled dust particles at the start of the test period.
Using a reader's question (see FAQs in this article: VERMICULITE INSULATION) as an example, if loose-fill vermiculite insulation were accidentally spilled in a building and then cleaned properly, we should find only comparatively low levels of vermiculite particles (or very low levels of asbestos if the vermiculite insulation originally contained asbestos dust and fragments).
In this case an old dust sample might find high levels, even dominant levels of vermiculite insulation in building areas near the spill or where HVAC systems transported building dust from the spill to other areas. A recent dust sample should find vermiculite fragments only low levels, perhaps just at incidental levels, and certainly not dominant level.
Interestingly, following a demolition and cleaning project, for example when mold contamination has been removed, it would be expected to find incidental levels of the original problem mold genera/species. Finding zero levels of such particles might raise question about the sampling approach.
Based on the theory above, which in turn is based on my field and lab experience in testing buildings for particulate contaminants, if you were worried that an original vermiculite spill had not been adequately cleaned, *or* if you wanted to know if the original vermiculite spill included asbestos, you might want to collect both a recent-dust sample and an old dust sample for comparison.
If, however, the cleanup was professionally conducted and post-cleanup testing was already performed properly, and if those steps indicated no problem remaining, in my *opinion* further testing would not be justified unless a new reason for further investigation is apparent. (Examples of such reasons are at MOLD / ENVIRONMENTAL EXPERT, HIRE ? and also at MOLD TEST REASONS.
If you have questions about the best particle sample collection procedure for your situation, Contact Us by email.
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 "Official Compilation of Codes, Rules and Regulations of the State of New York, Title 8. Education Department, Chapter II. Regulations of the Commissioner, Subchapter J. Buildings and Transportation, Part 155. Education Facilities", New York State Department of Education, web search 4/11/2012, original source:
Chain of Custody Form Printer friendly chain of custody form for identifying & submitting multiple mold samples
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
Fiberglass carcinogenicity: "Glass Wool Fibers Expert Panel Report, Part B - Recommendation for Listing Status for Glass Wool Fibers and Scientific Justification for the Recommendation", The Report on Carcinogens (RoC) expert panel for glass wool fibers exposures met at the Sheraton Chapel Hill Hotel, Chapel Hill, North Carolina on June 9-10, 2009, to peer review the draft background document on glass wool fibers exposures and make a recommendation for listing status in the 12th Edition of the RoC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.
Following a discussion of the body of knowledge, the expert panel reviewed the RoC listing criteria and made its recommendation. The expert panel recommended by a vote of 8 yes/0 no that glass wool fibers, with the exception of special fibers of concern (characterized physically below), should not be classified either as known to be a human carcinogen or reasonably anticipated to be a human carcinogen. The expert panel also recommended by a vote of 7 yes/0 no/1 abstention, based on sufficient evidence of carcinogenicity in well-conducted animal inhalation studies, that special-purpose glass fibers with the physical characteristics as follows longer, thinner, less soluble fibers (for 1 example, > 15 μm length with a kdis of < 100 ng/cm2/h) are reasonably anticipated to be a human carcinogen for the listing status in the RoC. The major considerations discussed that led the panel to its recommendation include the observations of tumors in multiple species of animals (rats and hamsters). Both inhalation and intraperitoneal routes of exposure produced tumors, although inhalation was considered more relevant for humans.
World Health Organization International Agency for Research on Cancer - IARC Monographs on the Evaluation of Carcinogenic Risks to Humans - VOL 81 Man-Made Vitreous Fibers, 2002, IARCPress, Lyon France, pi-ii-cover-isbn.qxd 06/12/02 14:15 Page i - World Health Organization, 1/21/1998. - Fiberglass insulation is an example of what IARC refers to as man made vitreous fiber - inorganic fibers made primarily from glass, rock, minerals, slag, and processed inorganic oxides. This article provides enormous detail about fiberglass and other vitreous fibers, and includes fiberglass exposure data.
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81.pdf - the article (large PDF over 6MB)
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6A.pdf - article details
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6C.pdf - studies of cancer in experimental animals in re vitreous fibers such as fiberglass;
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6E.pdf - summary of data reported & evaluation
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6F.pdf for the article references
To search the IARC monographs on various environmental concerns and carcinogens, use http://monographs.iarc.fr/ENG/Monographs/PDFs/index.php
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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.
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.