Guest guest Posted November 28, 2006 Report Share Posted November 28, 2006 It's been awhile since I asked this question, and it is about time to see if we have any new information. Has anyone lately done any analysis on duct dust, the dust that has accumulated in ductwork? If so, what did you discover? If you can, please delineate whether the dust came from the return or supply air ducts. Thanks. Matt ************************************************************ K. Klein, PE ME, MBA Matt: I don't know about "we" having new information or the findings being a discovery, but here is an excerpt from a report of a study in which I had dust samples analyzed microscopically to determine the constituent fibrous and particulate components for the purpose of confirming that the source of the settled dust in the room was the return duct (yes, high velocity air flow OUT of the return duct carried a huge amount of dust with it): Microscopic analysis showed that the settled dust sample from (the room) was about 60% fibrous materials and 40% particulate. Major fibrous components were cellulose, cotton and synthetic fibers in approximately equal amounts. About 25% of the fibers were dyed primarily blue, green and red. Minor fibrous components (< 5% of the total sample) were wool, fiberglass and other fibers. Fiberglass represented about one percent of the sample. In the analysis of the dust collected from the return duct in the ceiling of Room 211 it was determined that about 50% of the sample was fibrous material and 50% was particulate. Major and minor fiber types were similar to those in the settled dust sample. Fiber composition was about 20% cellulose, 15% cotton, 10% synthetics, 3% wool/others and 2% fiberglass. The fiberglass duct liner sample contained about 85% fibrous material and 15% particulate. Nearly all of the fibrous content was fiberglass. I hope that helps, Steve Temes Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 28, 2006 Report Share Posted November 28, 2006 Matt, I have found more dust in the returns then in the supply on most projects. Although I have ran into projects that had supplies not properly installed or torn down (more evident in crawlspace ducting) where there was a magnitude greater by 10 times. As with all other IEQ investigations I have done, there seems to be no hard and fast rules when it comes to ducts. Perhaps someone from NADCA has better statistics.... :-) Larkin Duct Dust It's been awhile since I asked this question, and it is about time to see if we have any new information. Has anyone lately done any analysis on duct dust, the dust that has accumulated in ductwork? If so, what did you discover? If you can, please delineate whether the dust came from the return or supply air ducts. Thanks. Matt************ ********* ********* ********* ********* ********* *** K. Klein, PE ME, MBAIndoor Air Quality Solutions, Inc.2523 SR 133Bethel, OH 45106-0007VOICE: FAX: (with notice)E-mail: mkklein68@roadrunne r.com************ ********* ********* ********* ********* ********* *** Everyone is raving about the all-new Yahoo! Mail beta. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 28, 2006 Report Share Posted November 28, 2006 Matt, On the return side, which in residential systems is always much dirtier than the supplies,most of the dust is house dust: skin scales, lint and pet dander. I have also found dust mites foraging in returns. Mold will grow in the dust if it gets wet (people often put boots to dry over floor grilles ) or if the dust is in a cool damp location (e.g. contact with concrete or in a crawl space.) Most of the debris in supplies has fallen in. I have found marbles and balls and moldy dog food and cheerios. One interesting phenomenon occurs in horizontal round ducts (at basement ceilings) and can often be seen with a mirror at a first-floor register boot. Only the lower half of the duct is coated with a very fine layer of dust. I believe that this dust is deposited after the blower shuts down. Hot air flows out of the system by convection at the top of the duct. Colder house air (which is denser) flows into the system at the lower half of the duct, depositing the dust at only the lower half. Relatively recent additions to duct dust are the 5-10 micron colored spheres from laser printers (these are the primary paint colors). Sometimes there are large numbers of spray paint spheres that get trapped on the surface of fiberglass-lined ducts. These spheres come in a large range of sizes (3-25 microns) and are full of pigment particles. The spheres are opaque (black) with transmitted light, and white using reflected light. Spider silk and insect droppings can be a large component in duct dust as well. C. May, M.A., CIAQP May Indoor Air Investigations LLC 1522 Cambridge Street Cambridge, MA 02139 www.mayindoorair.com www.myhouseiskillingme.com Klein writes: > It's been awhile since I asked this question, and it is about time to > see if we have any new information. Has anyone lately done any > analysis on duct dust, the dust that has accumulated in ductwork? If > so, what did you discover? If you can, please delineate whether the > dust came from the return or supply air ducts. Thanks. Matt > > ************************************************************ > K. Klein, PE ME, MBA > Indoor Air Quality Solutions, Inc. > 2523 SR 133 > Bethel, OH 45106-0007 > VOICE: > FAX: (with notice) > E-mail: mkklein68@... Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 28, 2006 Report Share Posted November 28, 2006 Matt, This is an indirect answer to your question, but I have routinely sampled the air filter in the HVAC system in residential settings. This of course, is located at the end of the return air stream. I take a " composite " swab sample of both sides of the filter to equal a total surface area samples of 100 cm2. My reasons for doing so are that these samples often present a good " picture in time " , and can be particularly interesting if you know approximately how long the filter has been in place, as well as in comparing the fungi and bacteria to other air and surface sample results from the structure. Obviously, a separate set of colonies can develop on the filter itself, particularly if it is very dirty/hasn't been changed in a long while so it's not always useful, but often is. In a situation with an extremely dirty filter, I will usually opt to not collect a sample from it. It also helps tremendously if the system is forced air (for the benefit of contractors who are consultant wannabes). On occasion, I've also sampled the filter medium in portable room air filters as well for the same reasons. Sometimes the results are more helpful than others, but that's how it goes when you're piecing a puzzle together. Some pieces fit, and some don't. Cheers, Chuck Reaney, CIAQetc & PIE (political incorrectness expert) To: IEQ List <iequality > Date sent: Tue, 28 Nov 2006 15:29:10 -0500 Subject: Duct Dust Send reply to: iequality [ Double-click this line for list subscription options ] It's been awhile since I asked this question, and it is about time to see if we have any new information. Has anyone lately done any analysis on duct dust, the dust that has accumulated in ductwork? If so, what did you discover? If you can, please delineate whether the dust came from the return or supply air ducts. Thanks. Matt ************************************************************ K. Klein, PE ME, MBA Indoor Air Quality Solutions, Inc. 2523 SR 133 Bethel, OH 45106-0007 VOICE: FAX: (with notice) E-mail: mkklein68@... ************************************************************ FAIR USE NOTICE: This site contains copyrighted material the use of which has not always been specifically authorized by the copyright owner. We are making such material available in our efforts to advance understanding of environmental, political, human rights, economic, democracy, scientific, and social justice issues, etc. We believe this constitutes a 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes. For more information go to: http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 29, 2006 Report Share Posted November 29, 2006 Chuck - Talk with your lab. They may prefer and be able to give you more information if you send a sample of the filter rather than take a swab. Sherryl Schultz OPTIMAL@... Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 29, 2006 Report Share Posted November 29, 2006 My suggestions for sampling mold on (in) air filters (1) Heavy dust load (loose dust on surface): micro-vac the surface on a measured area and then cut the entire measured area * Make sure your lab knows what to do with them (2) Light dust load (no loose dust on surface): cut a bulk piece (micro-vac optional) Swabs don't work very well on collecting subsurface mold. Wei Tang QLab Chuck Reaney wrote: Matt,This is an indirect answer to your question, but I have routinely sampled the air filter in the HVAC system in residential settings. This of course, is located at the end of the return air stream. I take a "composite" swab sample of both sides of the filter to equal a total surface area samples of 100 cm2.My reasons for doing so are that these samples often present a good "picture in time", and can be particularly interesting if you know approximately how long the filter has been in place, as well as in comparing the fungi and bacteria to other air and surface sample results from the structure.Obviously, a separate set of colonies can develop on the filter itself, particularly if it is very dirty/hasn't been changed in a long while so it's not always useful, but often is. In a situation with an extremely dirty filter, I will usually opt to not collect a sample from it.It also helps tremendously if the system is forced air (for the benefit of contractors who are consultant wannabes).On occasion, I've also sampled the filter medium in portable room air filters as well for the same reasons.Sometimes the results are more helpful than others, but that's how it goes when you're piecing a puzzle together. Some pieces fit, and some don't.Cheers,Chuck Reaney, CIAQetc & PIE (political incorrectness expert)To: IEQ List <iequality >From: Klein <mkklein68roadrunner>Date sent: Tue, 28 Nov 2006 15:29:10 -0500Subject: Duct DustSend reply to: iequality [ Double-click this line for list subscription options ] It's been awhile since I asked this question, and it is about time tosee if we have any new information. Has anyone lately done anyanalysis on duct dust, the dust that has accumulated in ductwork? Ifso, what did you discover? If you can, please delineate whether thedust came from the return or supply air ducts. Thanks. Matt************************************************************ K. Klein, PE ME, MBAIndoor Air Quality Solutions, Inc.2523 SR 133Bethel, OH 45106-0007VOICE: FAX: (with notice)E-mail: mkklein68roadrunner************************************************************ FAIR USE NOTICE:This site contains copyrighted material the use of which has notalways been specifically authorized by the copyright owner. We aremaking such material available in our efforts to advance understandingof environmental, political, human rights, economic, democracy,scientific, and social justice issues, etc. We believe thisconstitutes a 'fair use' of any such copyrighted material as providedfor in section 107 of the US Copyright Law. In accordance with Title17 U.S.C. Section 107, the material on this site is distributedwithout profit to those who have expressed a prior interest inreceiving the included information for research and educationalpurposes. For more information go to:http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to usecopyrighted material from this site for purposes of your own that gobeyond 'fair use', you must obtain permission from the copyrightowner. Yahoo! Groups Links QLab5 DriveCherry Hill, NJ 08003www.QLabUSA.com Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 29, 2006 Report Share Posted November 29, 2006 Thanks, Wei. I'll keep that in mind. Chuck To: iequality Date sent: Wed, 29 Nov 2006 13:30:45 -0800 (PST) Subject: Re: Duct Dust Send reply to: iequality My suggestions for sampling mold on (in) air filters (1) Heavy dust load (loose dust on surface): micro-vac the surface on a measured area and then cut the entire measured area * Make sure your lab knows what to do with them (2) Light dust load (no loose dust on surface): cut a bulk piece (micro-vac optional) Swabs don't work very well on collecting subsurface mold. Wei Tang QLab Chuck Reaney wrote: Matt, This is an indirect answer to your question, but I have routinely sampled the air filter in the HVAC system in residential settings. This of course, is located at the end of the return air stream. I take a " composite " swab sample of both sides of the filter to equal a total surface area samples of 100 cm2. My reasons for doing so are that these samples often present a good " picture in time " , and can be particularly interesting if you know approximately how long the filter has been in place, as well as in comparing the fungi and bacteria to other air and surface sample results from the structure. Obviously, a separate set of colonies can develop on the filter itself, particularly if it is very dirty/hasn't been changed in a long while so it's not always useful, but often is. In a situation with an extremely dirty filter, I will usually opt to not collect a sample from it. It also helps tremendously if the system is forced air (for the benefit of contractors who are consultant wannabes). On occasion, I've also sampled the filter medium in portable room air filters as well for the same reasons. Sometimes the results are more helpful than others, but that's how it goes when you're piecing a puzzle together. Some pieces fit, and some don't. Cheers, Chuck Reaney, CIAQetc & PIE (political incorrectness expert) To: IEQ List <iequality > Date sent: Tue, 28 Nov 2006 15:29:10 -0500 Subject: Duct Dust Send reply to: iequality [ Double-click this line for list subscription options ] It's been awhile since I asked this question, and it is about time to see if we have any new information. Has anyone lately done any analysis on duct dust, the dust that has accumulated in ductwork? If so, what did you discover? If you can, please delineate whether the dust came from the return or supply air ducts. Thanks. Matt ************************************************************ K. Klein, PE ME, MBA Indoor Air Quality Solutions, Inc. 2523 SR 133 Bethel, OH 45106-0007 VOICE: FAX: (with notice) E-mail: mkklein68@... ************************************************************ FAIR USE NOTICE: This site contains copyrighted material the use of which has not always been specifically authorized by the copyright owner. We are making such material available in our efforts to advance understanding of environmental, political, human rights, economic, democracy, scientific, and social justice issues, etc. We believe this constitutes a 'fair use' of any such copyrighted material as provided for in section 107 of the US Copyright Law. In accordance with Title 17 U.S.C. Section 107, the material on this site is distributed without profit to those who have expressed a prior interest in receiving the included information for research and educational purposes. For more information go to: http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use copyrighted material from this site for purposes of your own that go beyond 'fair use', you must obtain permission from the copyright owner. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 29, 2006 Report Share Posted November 29, 2006 Thank you, Sherryl. From: optimal@... To: iequality , iequality Copies to: " Chuck Reaney " Subject: Re: Duct Dust Date sent: Wed, 29 Nov 2006 19:26:31 +0000 Chuck - Talk with your lab. They may prefer and be able to give you more information if you send a sample of the filter rather than take a swab. Sherryl Schultz OPTIMAL@... Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 30, 2006 Report Share Posted November 30, 2006 Chuck, You are very welcome. BTW, did you tell us the reference where you get your PRV (clearance) criteria for surface mold? I am sorry that I didn't read all the posts. Wei Tang QLabChuck Reaney wrote: Thanks, Wei. I'll keep that in mind.ChuckTo: iequality From: Wei Tang <wtangQLABusa>Date sent: Wed, 29 Nov 2006 13:30:45 -0800 (PST)Subject: Re: Duct DustSend reply to: iequality My suggestions for sampling mold on (in) air filters(1) Heavy dust load (loose dust on surface): micro-vac the surfaceon a measured area and then cut the entire measured area * Make sureyour lab knows what to do with them(2) Light dust load (no loose dust on surface): cut a bulk piece(micro-vac optional)Swabs don't work very well on collecting subsurface mold. Wei TangQLabChuck Reaney <creaneyicdc> wrote:Matt,This is an indirect answer to your question, but I have routinelysampled the air filter in the HVAC system in residential settings.This of course, is located at the end of the return air stream. I takea "composite" swab sample of both sides of the filter to equal a totalsurface area samples of 100 cm2.My reasons for doing so are that these samples often present a good"picture in time", and can be particularly interesting if you knowapproximately how long the filter has been in place, as well as incomparing the fungi and bacteria to other air and surface sampleresults from the structure.Obviously, a separate set of colonies can develop on the filteritself, particularly if it is very dirty/hasn't been changed in a longwhile so it's not always useful, but often is. In a situation with anextremely dirty filter, I will usually opt to not collect a samplefrom it.It also helps tremendously if the system is forced air (for thebenefit of contractors who are consultant wannabes).On occasion, I've also sampled the filter medium in portable room airfilters as well for the same reasons.Sometimes the results are more helpful than others, but that's how itgoes when you're piecing a puzzle together. Some pieces fit, and somedon't.Cheers,Chuck Reaney, CIAQetc & PIE (political incorrectness expert)To: IEQ List <iequality >From: Klein <mkklein68roadrunner>Date sent: Tue, 28 Nov 2006 15:29:10 -0500Subject: Duct DustSend reply to: iequality [ Double-click this line for list subscription options ] It's been awhile since I asked this question, and it is about time tosee if we have any new information. Has anyone lately done anyanalysis on duct dust, the dust that has accumulated in ductwork? Ifso, what did you discover? If you can, please delineate whether thedust came from the return or supply air ducts. Thanks. Matt************************************************************ K. Klein, PE ME, MBAIndoor Air Quality Solutions, Inc.2523 SR 133Bethel, OH 45106-0007VOICE: FAX: (with notice)E-mail: mkklein68roadrunner************************************************************ FAIR USE NOTICE:This site contains copyrighted material the use of which has notalways been specifically authorized by the copyright owner. We aremaking such material available in our efforts to advance understandingof environmental, political, human rights, economic, democracy,scientific, and social justice issues, etc. We believe thisconstitutes a 'fair use' of any such copyrighted material as providedfor in section 107 of the US Copyright Law. In accordance with Title17 U.S.C. Section 107, the material on this site is distributedwithout profit to those who have expressed a prior interest inreceiving the included information for research and educationalpurposes. For more information go to:http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to usecopyrighted material from this site for purposes of your own that gobeyond 'fair use', you must obtain permission from the copyrightowner. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted November 30, 2006 Report Share Posted November 30, 2006 Chuck: You've peaked my interest. I am very surprised that sampling a filter (with the exception of a filter that is relatively new) would give any useful results. On culturables don't you get waaaay too many colonies to make heads or tails? And on optical microscopy samples, isn't there too much debris for an adequate reading? However, you've indicated that you do this with some regularity, so I have to assume you have been getting some data that makes sense. If possible, could you email me some of your lab reports from such samples to clk@...? Thanks. Cassidy Kuchenbecker > > To: IEQ List <iequality > > > Date sent: Tue, 28 Nov 2006 15:29:10 -0500 > Subject: Duct Dust > Send reply to: iequality > > [ Double-click this line for list subscription options ] > > It's been awhile since I asked this question, and it is about time to > see if we have any new information. Has anyone lately done any > analysis on duct dust, the dust that has accumulated in ductwork? If > so, what did you discover? If you can, please delineate whether the > dust came from the return or supply air ducts. Thanks. Matt > > ************************************************************ > K. Klein, PE ME, MBA > Indoor Air Quality Solutions, Inc. > 2523 SR 133 > Bethel, OH 45106-0007 > VOICE: > FAX: (with notice) > E-mail: mkklein68@... > ************************************************************ > > FAIR USE NOTICE: > > This site contains copyrighted material the use of which has not > always been specifically authorized by the copyright owner. We are > making such material available in our efforts to advance understanding > of environmental, political, human rights, economic, democracy, > scientific, and social justice issues, etc. We believe this > constitutes a 'fair use' of any such copyrighted material as provided > for in section 107 of the US Copyright Law. In accordance with Title > 17 U.S.C. Section 107, the material on this site is distributed > without profit to those who have expressed a prior interest in > receiving the included information for research and educational > purposes. For more information go to: > http://www.law.cornell.edu/uscode/17/107.shtml. If you wish to use > copyrighted material from this site for purposes of your own that go > beyond 'fair use', you must obtain permission from the copyright > owner. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted December 4, 2006 Report Share Posted December 4, 2006 Cassidy: I very often sample return air filters and supply air plenums. I consider the filter to offer the possibility of a long-term composite sample and therefore to be representative of material that has been present in indoor air for a prolonged period of time. Room HEPA filters are good for the same reason. I usually have both spore counts and culturable fungi analyzed. The absolute numbers are usually low by both methods, although dust may hide some of the spores. The relative viability (CFU/counts) is usually low, because of the low relative humidity of the air passing through the filter, unless there is a source of water affecting the return air plenum. Sometimes I get information that was not apparent from air samples but that may reflect source samples. I sample supply air plenums for evidence of water damage and mold growth from condensate backup, carryover, or other mechanisms. This allows an evaluation of the AHU and supply air system as a source for fungal contaminants in the indoor environment. It also allows evaluation of microbial carryover from indoor environmental contamination (mold and bacteria from water and sewage). I usually do this by cutting a wedge from the ductboard plenum and then cutting a thin slice from the inside surface and submitting that as a bulk sample. I also sometimes use swabs and sometimes micro-vac samples. If the plenum is not readily available or if it is metal, I smay sample supply air ducts and boots at registers, or I may open the AHU and sample the blower, the evaporator coil, or inside surfaces of the compartment, using swabs. This has worked in two recent cases to identify how far into which air handling systems sewage organisms progressed following sewage backup incidents. Don Schaezler, Ph.D., P.E., CIH ETC Information Services, LLC Cibolo, Texas Cassidy Kuchenbecker wrote: > > > Chuck: > > You've peaked my interest. I am very surprised that sampling a filter > (with the exception of a filter that is relatively new) would give any > useful results. On culturables don't you get waaaay too many colonies > to make heads or tails? And on optical microscopy samples, isn't > there too much debris for an adequate reading? > > However, you've indicated that you do this with some regularity, so I > have to assume you have been getting some data that makes sense. If > possible, could you email me some of your lab reports from such > samples to clk@... > <mailto:clk%40michaelsengineering.com>? > > Thanks. > > Cassidy Kuchenbecker > > > > > > To: IEQ List <iequality > <mailto:iequality%40yahoogroups.com>> > > > > Date sent: Tue, 28 Nov 2006 15:29:10 -0500 > > Subject: Duct Dust > > Send reply to: iequality > <mailto:iequality%40yahoogroups.com> > > > > [ Double-click this line for list subscription options ] > > > > It's been awhile since I asked this question, and it is about time to > > see if we have any new information. Has anyone lately done any > > analysis on duct dust, the dust that has accumulated in ductwork? If > > so, what did you discover? If you can, please delineate whether the > > dust came from the return or supply air ducts. Thanks. Matt > > > > ************************************************************ > > K. Klein, PE ME, MBA > > Indoor Air Quality Solutions, Inc. > > 2523 SR 133 > > Bethel, OH 45106-0007 > > VOICE: > > FAX: (with notice) > > E-mail: mkklein68@... > > ************************************************************ > > > > FAIR USE NOTICE: > > > > This site contains copyrighted material the use of which has not > > always been specifically authorized by the copyright owner. We are > > making such material available in our efforts to advance understanding > > of environmental, political, human rights, economic, democracy, > > scientific, and social justice issues, etc. We believe this > > constitutes a 'fair use' of any such copyrighted material as provided > > for in section 107 of the US Copyright Law. In accordance with Title > > 17 U.S.C. Section 107, the material on this site is distributed > > without profit to those who have expressed a prior interest in > > receiving the included information for research and educational > > purposes. For more information go to: > > http://www.law.cornell.edu/uscode/17/107.shtml. > <http://www.law.cornell.edu/uscode/17/107.shtml.> If you wish to use > > copyrighted material from this site for purposes of your own that go > > beyond 'fair use', you must obtain permission from the copyright > > owner. Quote Link to comment Share on other sites More sharing options...
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