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fibers not fiberglass (C) Daniel Friedman Composition of Building Dust or House Dust
Particle Types, Hazards, Identification

Composition of house dust or building dust:

This article describes the common as well as less-common constituents of house dust and typical office building dust. We also cite the occurrence of particles that may indicate indoor air quality concerns, hazardous conditions, or other building conditions that may be detected or perhaps simply suggested by the presence of certain particles in air, in settled building dust, or in vacuum-cleaner collected or clothes dryer-collected dust and lint.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

What are the Contents of House Dust & Office Building Dust

fibers not fiberglass (C) Daniel Friedman

Typical components of house dust and typical office building dust are dominated by fabric fibers and skin cells. Common too are lower levels of dust mite fecals, insect fragments, and air-delivered pollen and mold, though the levels of these varies seasonally and by changes in the indoor environment such as in humidity.

Watch out: usually the dominant constituents of house dust (fabric fibers, skin cells) do not pose a health hazard to humans.

However studies that we will cite here also have confirmed that in some buildings house dust may also include dust particles that carry potentially harmful carcinogens, endocrine disruptors, or that cause other illnesses or disorders.

Our photo shown above illustrates house dust containing fabric fibers, starch granules (upper center), skin cells (left), and probable soil-particles.

In a wet building skin cells and animal dander may also show secondary bacterial growth.

Below is an example of animal hair (cat) commonly found indoors. Even in homes where no pets are currently living, and often in homes where no pet has ever (been reported to have) lived we may find cat dander and on occasion dog dander and mouse dander.

fibers not fiberglass (C) Daniel Friedman

Normal Levels of House Dust

 

Cat allergens (cat dander) are common and are often more allergenic to building occupants than dog dander or animal hair in general.

fibers not fiberglass (C) Daniel Friedman

Our page top photo of typical "dust bunnies" that collect on building floors below furniture and under radiators, and our photo of a dusty table top (just above) are fairly normal of an indoor building prior to typical housecleaning vacuuming and dusting operations.

Watch out: dust is a common and normal material found in almost all buildings.

Do not seek an objective of "no indoor dust" in a normal building: doing so wastes money and time and is not rational. Only in controlled environments such as computer chip manufacturing lines do we expect to find few airborne particles.

Abnormal Levels of House Dust May Not be Acceptable

Very dusty indoor surface (C) Daniel Friedman

But abnormal levels of certain particles in building air or dust can indeed indicate an indoor air quality or indoor environmental problem that needs to be addressed.

Our photo at left shows a very dusty indoor surface characteristic of poor housekeeping.

Even if this dust contains only typical house dust components the dust level is likely to be irritating to some people (including the author) who are asthmatic or have allergies.

So how do we decide between just cleaning up obvious dust and debris indoors and the need to hire a building expert to look for hidden contaminants and if found to write a building remediation plan?

At MOLD / ENVIRONMENTAL EXPERT, HIRE ? we give a rational to help decide when further investigation of the indoor environment appears warranted.

Abnormal Indoor Particles Can Indicate Indoor Air Quality Problems or Health Hazards

We may however find either higher levels of common problem particles (allergens, insect fragments, mold, fiberglass or other insulation fragments) or low levels of particles that by their nature (such as Aspergillus sp. mold spores in chains) still indicate a problem.

Or we may find abnormal and possibly harmful levels of asbestos, concrete or silica, small fiberglass fragments, lead dust, mold at high levels, oil burner or fireplace soot, or non-particulate hazards such as gases or chemicals that are not addressed here.

Dust  mite fragment (C) Daniel Friedman

Our photo at above left illustrates a dust mite head fragment.

Dust  mite fragment (C) Daniel Friedman

Above is a cockroach insect jaw fragment. More often we see insect hairs, wing fragments, and fecal pellets.

While dust mite fecals are common in house dust, higher levels of actual insect fragments may indicate higher indoor humidity, or the presence of extra levels of mite sources (animals, animal dander, poor housekeeping).

See HUMIDITY CONTROL & TARGETS INDOORS .)

Fergusson et al (1986) point out that heavy metals may also be present in dust samples.

Also see LEAD POISONING HAZARDS GUIDE )

Still other biological hazards can be present such as bacteria and viruses. And particularly for buildings near highways, active streets, construction or demolition projects, tire particles, road dust, and CONCRETE DUST & ODORS can be significant ingredients in indoor air and in building or house dust.

All of these may appear at harmless, harmful, or suggestive levels in building dust or other indoor environmental samples.

In addition to our example data and photographs, this article includes citations to authoritative research on the components of house dust, building dust, vacuum-cleaner dust, and clothes dryer dust.

Dog dander allergens (C) Daniel Friedman

At above left we illustrate a microscopic close-up of dog hair, in this case from a golden retriever.

Dog dander allergens (C) Daniel Friedman

The photo above illustrates a mix of skin cells (larger fragments) and dog dander heavily stained with acid fuchsin. Normally these particles are hyaline (colorless).

Mouse hair (C) Daniel Friedman

Examining animal hair samples in a building may be diagnostic for a different reason. Above: chinchilla hair.

We may find examples of mouse or rat hair at levels suggesting a rodent infestation problem. In some areas rodent infestation is of course also associated with other diseases ranging from Hantavirus to plague.

The dust mite fecals in our photo at below left along with the background of this picture give important building diagnostics.

The fecal pellets themselves are comprised largely of mold spores, and in the background (not in focus) are spore chains that are most likely Aspergillus sp. or Penicillium sp.

Dust mite or other insect fecals (C) Daniel Friedman

While it is normal to find mold spores in both outdoor and indoor air ("all mold is everywhere all the time - it's just the concentration that varies" - Haines), observing mold spores that dominate the sample by frequency or even at low levels in chains is likely to indicate a mold contamination reservoir in the structure where this sample was collected.

See AIRBORNE MOLD SPORES CONCENTRATION BURSTS

Finding particle in connected chains - in this case both the fecal pellets and the Pen/Asp spores - often indicates a contemporary and nearby contaminant source. Why? Because normally in transport through air these chains are quickly broken apart into individual particles.

Watch out: We do not recommend that every building be screened for mold nor other problem particles. But when conditions warrant, further investigation is appropriate.

See MOLD / ENVIRONMENTAL EXPERT, HIRE ?

There may be other less-expected contaminants in building dust. For example, following a sewage flood or septic back-up in a building, both bacterial and viral hazards may be attached to common house dust particles.

See SEWAGE CONTAMINATION in BUILDINGS

Meruliporia fungal spores - house eating rot fungus (C) Daniel Friedmanb

An interesting example of a surprise particle found in building dust is shown in our photo at left.

While an initial inspection did not show structural damage to the wood framed home where this sample was collected, I saw some yellowish "dust" under a kitchen sink cabinet and on nearby sills. In the lab it was quickly apparent that we were looking at spores of Meruliporia incrassata or "poria" referred to by those who prefer scarier terms as "the house eating fungus".

We don't normally find this particle in buildings unless there is a rot problem. Further investigation of the building floor framing and sills found extensive rot damage that had not at first been apparent.

See details at MERULIPORIA FUNGUS DAMAGE

And the collapse of the world trade center demonstrated that in extreme conditions, for which more normal building remodeling or demolition are surely examples, dangerous levels of asbestos, lead, other metals, may be present in the building air and dust.

See details at WTC DUST PARTICLE - MICRO PHOTOGRAPHS

Flashlight dust © D Friedman at InspectApedia.com

Separate studies, especially by industrial hygienists, document airborne dust, chemical, or gaseous hazards more common in industrial buildings & complexes both indoors and outside.

Magnified to 720x dust particle fibers found in a healthy building are primarily cotton, wool, with some linen and a synthetic fabric fibers. Depending on the presence of carpeting the fiber mix will vary according to the carpet or other furnishings.

At left and in the photo at page top we illustrate simple settled dust on indoor horizontal surfaces. For building particle screening I like settled dust samples even though simple quantitative analysis cannot be performed.

By observing what particles are dominant in such a sample and by watching out for unusual particles that still form contamination clues we can get a good idea of what particles are actually indoors. At the same time we steer clear of the serious errors that plague highly precise but grossly -inaccurate air particle testing.

See ACCURACY vs PRECISION of MEASUREMENTS

and AIRBORNE MOLD COUNT VALIDITY

Watch out: While "air tests" or air sampling methods for particle collection are popular with many building investigators (quick, easy, profitable), such tests, when not accompanied by an intelligent inspection of the building exterior and interior along with a taking of building history, components, and occupant complaints, is simply not reliable, especially if results appear "negative" .

Details are at FALSE NEGATIVE MOLD TEST RESULTS

I elaborate this opinion at AIRBORNE MOLD SPORE COUNT ACCURACY .

Chemical Contaminants in House Dust

In some buildings, potentially harmful chemicals or particles borne in, on, or attached to particles of ordinary house dust. Some of these substances include lead, arsenic, Bisphenol-A BPA , cadmium, mercury, lead, pesticides, polycyclic aromatic hydrocarbons (PAH), and others.

It is possible that even at lower absolute levels particles bearing hormone disrupting chemicals or possible carcinogens such as PBDEs are unsafe, particularly for populations at extra risk, such as pregnant women, the elderly, children (Gevao 2006), people who are immune-impaired, asthmatics.

Details about chemical, metal, and similar contaminants sometimes found in building dust are

at HOUSE DUST CHEMICAL CONTAMINANTS

Fiberglass Fibers vs Fabric Fibers in House Dust

Certainteed blown in fiberglass (C) Daniel Friedman

Above we show a 720x micro-photograph of white blown-in un bonded InsulSafe® building insulation sold by CertainTeed. Just below our photo shows the dominant particles in the dust sample from the home under study.

fibers not fiberglass (C) Daniel Friedman

For instructions on how to collect surface dust for lab analysis,

see DUST SAMPLING PROCEDURE where we also discuss finding mold in indoor dust samples.

Typically we collect dust from building surfaces using clear adhesive tape or vacuum cassettes.

Details are at MOLD TEST KITS

and at VACUUM CASSETTE FILTER SAMPLE ..

House Dust Component Studies, References, Citations

Common toxins, pathogens, or allergens in house dust.

 




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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-08-22 by InspectApedia Publisher

@Michael Preciado,

I can see fabric fibers and some other white unidentified material - too blurry, magnification too low, possibly not correct slide mountant liquid (if any) .

Take a look at the article above on this page

and then click over to our article series beginning at

ALLERGENS in BUILDINGS, RECOGNIZING

Please post your further questions, comments, or photos there in order to get the quickest and most-pertinent replies.

Thanks

DF

On 2023-08-22 by Michael Preciado

Hi. I’ve been experiencing lots of allergies during the summer in our house lately and I just wanted your opinion of what this could be. I managed to put some of the dust around our house under a microscope. Please see the below image of 100x. Perhaps this is just fiber from clothing? Perhaps from insulation?

Thanks.

Michael

Microscopic house dust sample (C) InspectApedia.com Michael

This reader's Q&A were originally posted at HOW TO CONTACT InspectApedia.com 

On 2021-07-25 by inspectapedia.com.moderator

@Lori,

Yes, carpet padding can be moldy as can be a floor surface below the padding without mold showing on the carpet upper surface.

However the dust from your photos looks like fabric fibers or classic house dust.

It's typically shredded by a carpet or mattress or bedding or other fabrics.

...

The ceiling light chain will collect dust, particularly if the surface of the chain itself is sticky and is collecting Fabric and other normal house dust fibres that are airborne.

The chain is in fact by its design and placement an excellent dust collection device.

In particular if its surface is made to be sticky for example by a light coating of oil or by the finish itself.

On 2021-07-25 by Lori P

@inspectapedia.com.moderator,
Thanks for your replies. This photo is of the carpet and baseboard under my bed. It was a 1-2 inch web-like dust that I mentioned in my first post. This area is hard to access but it gets vacuumed at least every 3 months. I'm attaching another photo

This is an air purifier that I bought last week and placed in my bedroom. When I picked it up to move it today, it was covered in the web-like dust

. It looked like something that had not been dusted in years but was only a week old. What could possibly cause this excessive webby dust besides the obvious factors such as dogs and carpet fibers? Any ideas?

@inspectapedia.com.moderator, this wasn't just on a small portion of the chain. It litererally covered the whole 7ft chain from top to bottom even though I constantly used a feather duster every time I dusted (weekly). It is sticky and hard to remove.

@inspectapedia.com.moderator, I was just wondering, could carpet padding have mold without it showing through to the carpet? It is interesting that the carpet "dust" was more concentrated.

On 2021-07-16 by inspectapedia.com.moderator (mod)

@Lori P,

It certainly would be common for a small cobweb on a light chain to collect house dust

It is also entirely common to see an accumulation of house dust on the leading edge of a ceiling fan blade;

The usual components of house dust are described above on this page.

If you feel that your home has unusual levels of house dust, consider the common sources such as carpets, bedding, pets.

To achieve a low-house-dust level in a home we'd need to reduce those common sources.

Only if a forensic lab finds significant levels of unusual or harmful particles in your dust would it be a possible health concern; examples would be high levels of allergens or mold.

We don't have rules limiting the number of photos or posts permitted to a reader, though in some egregious cases we may of course edit or delete some material.

About the "web under your bed" it's not an image that I can interpret;

On 2021-07-16 by Lori P - heavy house dust complaints in Tucson

Hi there,
Thank you for your website. It's been very helpful. Unfortunately, I have been searching all over the internet looking for similar photos related to the dust issues we are having in our home but haven't had any luck. It's like nothing I have ever seen before.

I am currently looking for a forensic lab in my area (Tucson) but haven't had much luck thus far. Anyway, I was wondering if you have ever come across something similar to what we are experiencing.

I keep a very clean house but like most people, only dust inaccessible areas (i.e. high ceiling fans, under beds, high pot shelves, behind dressers, etc.) about every 3 mos.

It is expected to have more dust living in the desert but this is just a little excessive. I wish that I could post more than one photo because you have to see it to believe it. This photo is the ceiling fan in our bedroom that is on 24hrs a day.

It was dusted 3 Mos ago and did not look like this. I have this web-like dust in other areas as well. It was just as bad under my bed where it is hard to vacuum without lifting the bed (and is vacuumed every 3 mos). 2 ft from where we sleep, their was a 2 inch dust web that covered the floor and crawled up the base boards.

When I vacuumed it, it sucked up together and looked as though the floor was crawling/moving. To my eye, there were no bugs or spiders seen. The health of my family has been deteriorating over the last years and I now suspect that this could be the cause.

We had a leak 5 yrs ago in our master bath but was told that mold doesn't grow in Tucson. Have you ever seen this before? I sure wish that you guys still did testing. I don't know what to ask for because if mold doesn't grow in Tucson than what could be causing it?

We do have valley fever here which is caused by a fungi. Could that collect on dust and if so, would they look for that? Do you know anyone in Tucson who could help? I'm desperate! Thanks in advance.

 

Cont... Here is the image of the "web" under my bed. I would like to post 1 more. I'm sorry if this is against the rules. Thank again.

Thick dust under bed (C) InspectApedia.com Lori

Cont... this is a chain that is connected to a hanging light in my bedroom. I dust the chain all the time with a feather duster. It wasn't until I got onto a ladder to really clean it when I saw this web-like dust that is sticky and needs to be pulled off. It's almost like it is attaching to the objects. Thank you for letting me post. Maybe someone else having the same problem will have ideas.

House dust on light chain (C) Inspectapedia.com Lori

On 2020-09-18 by danjoefriedman (mod)

Bob

The most-common fibres that I find in house dust and therefore that are expected to be found on HVAC filters and similar equipment are fabric fibers from clothing, carpeting, furnishings, draperies, etc. To identify the specific fibers you'd need a forensic lab to make a microscopic examination, typically including the use of polarized light.

It's normal to find this material and it's not, in my view, deserving of lab analysis unless you have reason to be tracking down a specific building problem or health issue.

On 2020-09-18 by Bob Reed

In our 1700 sq' home, we have two Winix air filtering machines operating 24-hrs a day. In 10 days of operation, the outer mesh screen is covered with an obvious (collectible) coating of very fine airborne fibers. The color is primarily grey. It is flammable. It closely resembles the dust collected from a clothes dryer. This has been continuing for a couple of years and seems to be getting worse.

Our obvious possibilities are: wool carpet (tan) throughout the house, and blown-in ceiling insulation (white), We have no pets or children. The laundry room / clothes dryer discharge seems intact and there is little dust in that room or under the house.

Suggestions? Should we send collected samples to a testing lab? Can you recommend one?

On 2019-05-16 1 by (mod) - where I could purchase household dust for use in lab testing?

Re-posting from private email:

Would you have information regarding where I could purchase household dust for use in lab testing?

Sandra Villarreal EMAIL: SAVillar@scj.com

Moderator reply:

For the purpose of studying house dust one would perhaps want to know the characteristics of the building where the dust was collected, country, city, age, leak, mold and other conditions, building materials, occupants, presence or absence of pets or other animals, number of occupants, medical conditions, furnishings, etc.

For purposes of using house dust to calibrate forensic equipment one might want to know the consistency of the dust across a sample of given volume.

Household dust is ubiquitous and free and easily collected by tape samples, sweeping, or vacuuming,.

Therefore I think you'd need to define your lab testing requirements more explicitly for us to suggest a different answer than don't buy house dust, "it's free" and "it's everywhere".

As it will be helpful to other readers, and as its publication may prompt other readers to offer a helpful suggestion about lab-use dust sources, I will include of this discussion in our article at

HOUSE DUST COMPONENTS

near the bottom of that article as a Q&A.


...

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HOUSE DUST COMPONENTS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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