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Asbestos in Settled Dust

dusty attic; dust in the home; house dust

In homes throughout the nation built before the 1980s, asbestos containing materials were commonly incorporated. Asbestos was used because of its high durability, fire resistance, and other favorable properties. Asbestos was used in drywall, plasters, floor tiles, HVAC insulation, plumbing insulation, adhesives, and many other products. Asbestos containing materials in the home become a health risk when they are damaged, disturbed, and made friable, which releases the asbestos fibers into the air. Typically asbestos fibers can remain airborne for up to 72 hours in area of low air movement, afterwards falling to the surface and generating dust.

The larger the release of fibers from asbestos containing materials, the more dust it generates once the fibers settle. As a mineral, asbestos can remain in the dust indefinitely and does not degrade. If an asbestos containing material was improperly abated in a home, this could lead to the settled asbestos dust being disturbed in the future.

Unlike asbestos air testing and inspections, there are no federal or state regulations on settled dust sampling. The bulk of our understanding on asbestos dust is based off of industry guidelines. The method we use at Indoor Science for dust sampling is called TEM Microvac. This process involves taking a filter cassette and attaching it to a high volume air pump, which sucks dust onto the filter.  We generally collect dust from a 100 cm2 area. The cassette is then analyzed at an accredited laboratory by an electron microscope which can scan the cassette and identify the amount of asbestos fibers found. This method is called TEM, which stands for Transmission Electron Microscopy).  

The laboratory reports the results as asbestos structures per square centimeter.  As previously stated, there is no governmental regulation for a permissible amount of asbestos fibers in the dust.  Nevertheless, there are industry guidelines that help us interpret if the fibers found in the dust are background levels, elevated, or highly elevated.

If you have concerns about settled asbestos dust in your home. Feel free to contact us.

Ian Cull

Ian Cull is a nationally recognized expert in the field of indoor air quality. He is the Chief Science Officer of Indoor Science, a company he started in 2004. He speaks around the world on air quality topics and is a training provider of the Indoor Air Quality Association. Mr. Cull is a Licensed Professional Engineer (PE) and Certified Industrial Hygienist (CIH). His degree is in Environmental Engineering from the University of Illinois - Urbana Champaign. Mr. Cull has developed 50 air quality related courses for the IAQA University and is the author of the book, “Fundamentals of Mold Remediation”. In his words… “Besides being passionate about indoor air quality, I enjoy cycling, music, the Chicago Bulls, and having fun with my three kids.”

22 thoughts on “Asbestos in Settled Dust

    I cannot find any reference document on the internet to see what a chart to sow a range of particle counts. I am not looking to make a health assessment, because I understand any asbestos is bad. But I would like to understand how any specific ‘counts’ compare to the total low to high range used in logging, categorizing severity of presence. Are readings from 1 to 1 hundred or 1 to 1 million? A friend has raised my curiosity by telling me he had testing done because the last owner had replaced the floors and someone told him he should test in case the mastic under original floor was disturbed causing particles to be floating around in the air. He ad a service come out that performed a 3 hour air test from 5 areas within his home plus a total of 19 surface (swipe samples) in specific spots chosen by the testing professional as most likely places to find residual particles. All air tested came back as negative (as in no particles found, not just a negligible number of particles). So the initial thought was that no current source of release is present or been disturbed. Of the 19 surface dust swipe tests, only 3 came back positive for a presence of asbestos particles. He gave me a number, but I did not have the privilege to see a written report, so I have not idea what his results mean. He told me that one swipe sample taken reaching in under the kitchen cabinet on the original cement floor was 10,000. A second swipe taken on an out of reach (not been dusted by homeowner in some time) window sill in kitchen bay window also came back as 10,000. The third was the top of a mirror frame in the living room, (again out of reach and not likely cleaned often if at all) adjacent to the kitchen came back as 70,000. Can you put this into perspective for me. My wife is now thinking we should have testing done too.

    Hello Tom,

    The references are from the books “GOLD STANDARD FOR REMEDIATION OF WTC CONTAMINATION” and “Settled Asbestos Dust Sampling and Analysis” which go over the ranges. If the result shows less than 10,000 it is considered background levels. If the range is between 10,000 to 100,000 is considered elevated we recommend considering abatement activities. If the level is above 100,000 we consider this highly elevated and recommend immediate abatement activities. The highest I have seen in the field is over 1,000,000.

    My house was built in 1973, and in recent years we have been doing renovations. I am studying for a real estate license, and through that was the first time I was ever made aware about asbestos. My dad is a contractor, and he did many of the renovations, but even he was unaware. The first exposure I can recall was five years ago, but I am sure we have been doing minor renovations earlier than that. I know it’s possible for there to only be minimal asbestos, if any, but I struggle with anxiety and this whole ordeal is killing me. What should I do?

    Hello Erik,

    Asbestos-related illnesses are generally caused by chronic exposure and in rarer cases shorter-term exposure. The best thing for moving forward to have materials tested before renovation activities and limiting your exposure as asbestos exposure is cumulative.

    We had a certified professional collect dust samples to test our house for asbestos. We collected samples from 6 rooms. 3 of the rooms tested were found to have 1 fiber. I have no idea how to interpret this data. Do you have any guidelines? You mention industry standards. Where can read up more on those?

    Thank you

    I live in a town house built in the 1940s. My neighbors, who just bought their place, began massive remodeling (drilling, etc). My husband and two year old were home all day. Lying in my bed right now, I can smell the saw dust, which makes me think that air/particles may have come through the vents. Is that likely?

    Also, the neighbor on the other side of us is planning a major remodeling effort as well inthe coming weeks. My understanding is that our homes used to be connected (we share water pipes, for example). Should I be concerned?

    Hello Maryanne,

    It is possible that the dust created from the renovation may be coming into your unit. I would speak to contractor and discuss dust suppression such as containment, negative pressure and possibly utilizing water. I would also ask if the materials that are being removed have been tested for asbestos due to the age of the building.

    I had a sump pump installed in my basement. The contractor drilled through 1 feet into the floor around the walls to make the drains. In the process he had to drill through many tiles which I am not sure but could be asbestos.
    The contractor said he would cover things around the basement, but did not cover the in-vent for the AC until 2 days of work.
    Also my AC unit is in the basement.My kids were upstairs.
    As I read more I understand a little more.
    My fear is the contractor probably did not have take necessary precaution which he should have and asbestos dust and fibre could have gone into my house.
    What should I do?


    I would recommend having the tiles tested to confirm they are asbestos-containing. I would recommend conducting TEM dust sampling or aggressive TEM air sampling in the area where the tile was drilled and also random sampling in other areas to see if any asbestos was spread from the work.

    Thankyou for your quick response.
    The plan is to retile over the existing tile.
    Can I wait for TEM dust testing for after the retiling and new floor is laid out?
    Or it is better to do the test immediately?

    I would recommend having the dust testing first since a potential asbestos-containing material may have been disturbed.

    I am freaking out!!!. My husband and i are renovating our family room. We decided to scrape up the tile floor. There were 2 layers and under the first layer is the black adhesive which i read has,asbestos in it. We had the room sectioned off with plastic but not air tight enough. Freaking out because now that i know the chance of there being asbestos since my house,was built in 1960, im afraid the dust went throughout the house and my daughter was home. Please tell me if she would have breathed any in. Please help! Im literally hysterical about this!
    Thank you,
    Tamara McMakin

    Hello Tamara,

    Without air monitoring during the abatement activity, it would be difficult to say how much asbestos was released. I would recommend conducting aggressive air or dust sampling in the space to determine if there is any residual asbestos in the air or dust.

    Hi Tamara
    What did you end up doing? I had a contractor dig drains in my basement and he drilled through the floor.
    My fear is he drilled through asbestos tiles and did not take proper precaution.

    An elementary school that had asbestos removed was refurbished and converted into an apartment complex. Also, a brand new apartment addition was built next to the converted elementary school. I’m thinking about moving into the next door new addition building because I think there’s no way I could know that asbestos doesn’t remain in dust form in the renovated part of the complex. Are my concerns legitimate?

    Hello Sammy,

    When asbestos is removed from a school, it is done using a strict protocol called AHERA. While it would not be impossible to find a background amount of asbestos fibers in the dust in the new addition, it would be unlikely to be elevated due to the stringent rules of AHERA clearance criteria.

    I’m glad you pointed out asbestos-containing structures become a health risk in your home if they are damaged or disturbed. My husband and I recently moved into an older home, and we think there may be asbestos in some of the basement fixtures. I don’t want to disturb them and release the asbestos into the air, so I think we’ll call a professional who will know how to safely remove it.

    Malibu is devastated. It has rained so how often should we be sampling the air? What about the soil since there is no regulation on dust? The district is testing it has rained and as an AP Environmental teacher I would expect much dust and with the winds there again the smaller lead particles and asbestos dust become particulate matter in the air? What can we do or ask for in order to make sure we continue to guarantee the safety or our students, teachers and classified employ’s?


    Hello Charles,

    I recommend testing when materials have been disturbed. Since the fires have caused much dust to be spread, I would recommend testing if there is visible dust caused by the fires on the school property.

    I’m due to have my house asbestos from ceiling removed.
    My housing have arranged a company to do this but I’m very worried about this being done as i have 2 children with breathing problems asthma and I have just been prescribed an inhaler as im experiencing breathlessness.
    My ceiling has cracks in already and I have 4 children 3 autistic.im being told im safe to stay here even after but I’m not sure please could u give me some advise as to whether to seek a move.

    Hello Lisa,

    Without inspecting the containment or the site it is difficult to say whether to stay or leave. I would recommend making the decision based on your health concerns. Abatement activities should be performed inside a containment with negative air pressure which if used properly should keep air from breaching the containment. I would recommend that the abatement company conducting the work to set up air samples outside of the containment to see how the work is affecting the air quality in the home.