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Community and Q&A

Non-toxic ductwork

Evan&Suzy | Posted in Green Products and Materials on

We are researching truly non-toxic ductwork for our all new electric heating/cooling… HVAC system. We are only finding the usual hardpipe which is known to be coated on inside with rust proofing, and the flex. The flex is found to be polyester and nylon in the interior with a wrap of insulation, probably but we’ve not been able to find that info yet, probably has fire retardant and formaldehyde, and who knows what. then the outer black plastic layer or silver whichever, silver would be best as all plastics outgas toxic fumes and when heated… even moreso. If someone could please point us to some truly non toxic ductwork… for a chemically sensitive person. Most normal people wouldn’t notice but all of us do, and must have all the toxic chemicals out of the line of fire, so to speak, as best we can. Thanks for any suggestions at all.

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  1. GBA Editor
    Martin Holladay | | #1

    Evan and Suzy,
    Galvanized steel ductwork, to the best of my knowledge, is simply steel coated with zinc. When I was growing up, every bucket and bathtub on every farm in America was made of galvanized steel, and I never heard that galvanized steel was considered toxic. (Actually, some farm buckets included lead solder, and lead solder was a bad idea. But I can assure you that lead solder is never used for ductwork.)

    Many older homes have water pipes made of galvanized steel.

    I don't think that galvanized steel ductwork is coated on the inside, but I suppose you could have your contractor wash each piece of ductwork with soap and water before it is installed -- assuming, of course, that you can tolerate some kinds of soap.

  2. GBA Editor
    Martin Holladay | | #2

    Evan and Suzy,
    One more point: In general, ductwork is non-toxic -- which is to say, there are no reports of homeowner poisoning related to ductwork installed in their homes.

    You've described yourself as "chemically sensitive." That means that there really are no rules that apply -- only you know what you can tolerate. You'll have to experiment; I don't know of any other way to determine what sets off a reaction in a person who is chemically sensitive.

  3. Andrew_C | | #3

    If you are at the design stage, why not consider eliminating ductwork? Ductless minisplits are often a good solution, especially if you are all electric.

    1. ecodude | | #20

      Great choice!

  4. GBA Editor
    Martin Holladay | | #4

    Evan and Suzy,
    As Andrew noted, it's possible to have a duct-free house.

    For heating and cooling, use ductless minisplits.

    For ventilation, use Lunos fans.

  5. benasp | | #5

    Hi Martin, you may want to look at this recent research

    However, historical research documents that the grade of zinc typically used for galvanizing contains a minimum of 0.5% lead and can itself be a significant long-term source of lead, which may explain some recent lead contamination problems associated with galvanized steel

    Not to be confused with the actual question which relate to air contamination and not water.

    For the actual question, it might also be hypochondria, which can't be resolved with any type of duct material.

  6. GBA Editor
    Martin Holladay | | #6

    I appreciate the link. Lots of older homes I've worked on in this part of Vermont have galvanized water supply pipes. My family often hauled water in galvanized buckets when we went camping as kids.

    I guess that means I would have been a little bit smarter if only there was less lead in the water I drank as a child.

    Still, as you point out, I've never heard of any poisoning caused by galvanized ducts.

  7. Jon_Harrod | | #7

    I've noticed a light oily coating on adjustable sheet metal parts like elbows--presumably there to prevent corrosision and binding. One chemically-sensitive customer we worked with asked that the ductwork be washed with soap prior to installation. If you're committed to a ducted system, I'd recommend buying a couple sheet metal elbows, washing them, and seeing if they bother you. Once the oils are removed, you should have a durable, inert distribution system.

    That being said, I'd also echo the recommendation to explore a ductless solution.

  8. Jon_R | | #8

    As far a I know, steel, zinc and even lead don't off-gas at all at duct temperatures, leaving only mastic as a possible concern. Contact with drinking water is quite different than air.

  9. Evan&Suzy | | #9

    Thank you all for your helpful replies. Looks like Jon Harrod is the only one with experience working with chemically sensitive customers. This I can attest is a living hell worse than death, the blessing, with the situation such as it is with the above the norm. 'No one's ever heard of anyone being poisoned,' and so on. No one's ever heard of US testing gadgets being 1000 points lower, at least for carbon monoxide and gas, than the European testing devices, because that information is not advertised here. I can't find the article so don't quote me but that's what I recall from an article in Our toxic Times, years ago now, and nothing has changed here to date as far as I know. I'm suffering another gas and carbon monoxide exposure, yes, another, due to yearly maintenance not having caught the problem soon enough, again, so I'm not able to do any digging with life saving measures again taking up all my time. See also: and so many others I couldn't remember a fraction of them. We don't have the toxicity information we need because no one's ever tested it. When toxic injury comes on imperceptibly, incrementally, one would not notice, then... bam. Of course the medical establishment won't have a clue unless one connects with a chemical injury physician, a growing profession these days. No one's tested any of these duct products for long term accumulation of poisons therein so there is no data. The oil on the galvanized steel is probably rust proofing. That is NOT non toxic. Mastic is NOT non toxic. But there are other 'mastic' products now what are 0_VOC. I tested the flex duct via 3 different modalities and as injured as I am right now, I reacted to it badly. I will have to find out if we can do the ductless mini splits which is probably the best deal. We did have to wash that 'oily' coating off metal when this furnace was installed in 2003, but I wouldn't know if that bothered me, us, because the gas valve stuck open for 3 months. I was fighting about it going down the tubes along with Evan, in denial as most men always are, and finally somehow managed to call the gas company. The division manager himself came out and found the gas valve had stuck open the entire 3 months while I was getting the nutcase and 'hypochondriac' rackets run on me, us... The division manager said, 'its a miracle it didn't explode.' Evan didn't even know where he was, driving to town, going east west trying to get to a northerly destination, screaming at me as if I was telling him the wrong way to go. That's men. Even with 10 prior years of the same, different materials, like OSB, supposed to have been taken off market... I was doing so well before that gas leak and have been unable to gain the degree of recovery from the initial death and back status i suffered, that I enjoyed before the gas 3 month gas leak. I've suffered 24 years of repeated chemical injury from different poisonous sources, some of which have been taken off the market since, but i got the nutcase routine run om me, like most women and children, every time. But every time I was right, and there really was something seriously poisonous in our small house, and I proved it with tests on the house, the offending whatever it was, any myself, thereafter, available upon request. That said, it would be a good idea to rethink this entire situation and come up with duct work that is truly NON toxic, even if most people think they are doing OK with the status quo. So many people and children suffer from Asthma, COPD, cancer, brain and nerve related issues without a cause. It's always the illusive obvious. I've come up with a readily available material for duct work that could hit the 'green' and' healthy hous'e markets immediately. If there is anyone out there who would like to help me get this going, that usually means funding and startup, all that, I'd appreciated it. So far, I've given all my grand ideas away which went into not millions but billion dollar sales on one idea, and I'm not doing that again since I was not able to claim compensation for most of the chemical injuries I suffered during this new construction and remodeling nightmare. Please see all the links above and links they provide. MCSRR has profound info on CO, and a lower range CO tester, so that's a do not miss. Thank you all so much for your replies. It's time to take indoor air quality to the next level... something on the order of what NASA is using for the astronauts in space and space station. The Mitsubichi ductless is one, as I recall. I was going to check on what they're using for duct work today... I'll let you know. Thanks again.

  10. Expert Member
    MALCOLM TAYLOR | | #10

    Evan and Suzy,

    The CMHC (Canadian Mortgage and Housing Corporation) has done a lot of work on housing and environmental sensitivities, including building units for those suffering from the affliction. You may find a search for CMHC + chemical sensitivities or something similar would yield some useful advice.

  11. Evan&Suzy | | #11

    Thank you, Malcom Taylor, and everyone above. I'm not finding materials info for NASA's ISS. I'll see if I can find the CMHC + chemical sensitivities you offered. I've emailed our contractor with all your info and suggestion on the ductless mini split. We'll see what he says. I'm having another bad reaction about something since yesterday afternoon with the cause still at large, so, this is a good time for those who offered their kind replies above to get a glimpse into what a hell this is. More and more people are joining the ranks and most contractors green or otherwise don't know how to handle it. Martin, et al, I truly appreciate the offerings. I'm checking out the Lumos fans now. I hope our contractor is up to speed. Sorry about the long post, but tells the tale of this horrid 24 year nightmare and how to live through it. Testing out each product is the only way as everyone is 'party specific.' But even testing, a little used in a test is not the same as a ton of it installed. And it's always too late after the fact. I'm having trouble understanding lumos fans with the brain damage... and everything else for that matter. I need someone in here to do this for me while I get treatment at a bona fide chemical injury clinic for once. The galvanized duct is an extra $4000. How can I afford it? Is there financial help for people like me?

  12. Evan&Suzy | | #12

    Thanks, Malcom. I found this. I'll contact them and see if they have suggestions for non toxic duct work. The galvanized seems best if I can't do the ductless for some reason.

  13. gimmecleanair | | #13

    Evan and Suzy,
    Did you find a solution? This post is 3+ years old. I'm sorry you have been going through all of this. I can relate. I have had chemical sensitivity since the summer of 1993. In the last year and a half I went through a disaster with new plastic flexible air ducts, then had them all taken out. Then, because I believed that sheet metal air ducts were inert as far as air quality and would have NO effect on the indoor air quality I spent a ton of money getting all new sheet metal air ducts in my attic. This is for a 3 bedroom house 1,500 square feet. It was twice the cost of the plastic flexible air ducts. They took 2 days to install them and on the 2nd night my sleep was just awful. That is how my chemical sensitivity affects me - it disrupts my sleep and also causes headaches. In this case it is also making me feel spacey in my house. All of this began right after the new sheet metai air ducts were installed.

    I asked the contractor for specs on the sheet metal. He referred me to the sheet metal wholesale outlet from which he had bought the sheet metal. The wholesale outlet sent me a material safety data sheet (MSDS) which was from USS-POSCO Industries in Pittsburg, California. The product(s) was / were Galvanized (hot dipped) sheet, carbon steel, Galvanealed (hot dipped) sheet, carbon steel, and UPLGalXCSheet, carbon steel. The MSDS overall claims that the products are harmless but that
    here is what it said. “As sold, this product is not considered hazardous under Cal-OSHA 8CCR Section 5194 and OSHA 29CFR Parts 1910.1200 Hazard Communication Standard, steel products are considered articles/mixtures due to further processing which may product dusts and/or fumes. However, individual customer processes, (such as welding, sawing, brazing, melting, grinding, abrasive blasting, and machining) may result in the formation of fumes, dust (combustible or otherwise), and/or particulate that may present the following hazards:

    OSHA Hazards
    Skin Sensitizer
    Target Organ Effect
    Target Organs: Respiratory system.

    GHS Classification:
    Carcinogenicity (Category 2)
    Skin Sensitization (Category 1)
    Specific Target Organ Toxicity (STOT)-Repeated Exposure (Category 1)
    Specific Target Organ Toxicity (STOT)-Single Exposure (Category 3)
    Toxic to Reproduction (Category 2)
    Acute Toxicity – Oral (Category 4)
    Eye Irritation (Category 2B)


    Hazard Statements
    May cause an allergic skin reaction
    Suspected of causing cancer
    Suspected of damaging fertility or the unborn child.
    Causes damage to lunds through prolonged or repeated inhalation exposure.
    Harmful if swallowed.
    May cause an allergic skin reaction.
    May cause respiratory irritation.
    Causes eye irritation.

    Precautionary Statements

    Do not breath dusts / fume / spray.
    Wear protective gloves / protective clothing / eye protection / face protection.
    Contaminated work clothing must not be allowed out of the workplace.
    Use only outdoors or in well ventilated areas.
    Wash thoroughly after handling.
    Obtain special instructions before use.
    Do not handle until all safety precautions have been read and understood.
    Do not eat, drink or smoke when using this product.
    If inhaled: Remove person to fresh air and keep comfortable for breathing.
    If exposed, concerned or feel unwell: Get medical advice/attention.
    If in eyes: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
    If on skin: Wash with plenty of water. If irritation or rash occurs: Get medical advice/attention. Take off contaminated clothing and was before rinse.

    Section 3 of the MSDS is about the composition of the sheet metal, the ingredients and the percentage of each. I will attach a screen shot of that section.

    Overall I would say DO NOT get sheet metal air ducts in your house. This is a big multi thousand dollar disaster. Also, don't sign a contract that has a section that says if there is a lawsuit over breach of contract the prevailing party can recover their attorney fees from the other party. That's a big mistake that I made. I am going to sue them and take that risk, but if I lose the court could order me to pay thousands of dollars in their attorney fees. This could become an even bigger disaster.

    I don't know what kind of air ducts would work. I am very interested in your idea Suzy but I am not loaded with money and have never developed a product. I agree, don't give away your ideas for free. Maybe you can get a patent on your idea and then discuss it with someone. Good luck!

    1. Expert Member
      MALCOLM TAYLOR | | #14


      The hazards listed ( cutting, machining etc.) are related to the process of installing the ducts. There are all sorts of building materials - including wood - that are inert but can be hazardous during their manufacture. There is absolutely who reason not to use them in a house if you are environmentally sensitive. A good analogy would be heating up a homemade soup on a gas range. The cook may be exposed to harmful particulates, but the person who consumes the soup isn't.

    2. Patrick_OSullivan | | #23

      I look forward to reviewing the peer reviewed data documenting the serious risks of metal ductwork to occupant health, particularly those with chemical sensitivities.

      Given the prevalence and verifiability of these problems, surely this research data exists.

  14. gimmecleanair | | #15

    Malcolm Taylor,

    If you read what I showed from the MSDS it said that sawing the sheet metal can produce all of those hazardous conditions and health effects. And they sawed the sheet metal in the process of installing the air ducts.

    Your blanket denials to the contrary, my own experience shows (too late) that one should NOT use sheet metal air ducts. They have polluted the air in my house.

    A person with chemical sensitivity has to be really careful. Suzy mentioned that there is a big difference between testing a small piece of something and a whole attic full of it. Even when we are careful we sometimes make mistakes.

    A person with chemical sensitivity should NOT use sheet metal air ducts based on my experience right now and for the last 5 weeks. It has been an ongoing disaster health wise. I don't know if you have chemical sensitivity. You didn't say. The point is to err on the side of caution (not taking the unknown risk) and to learn from the experiences of others. I put my story out there for the purpose of enabling others to learn from my experience and do with this information what they will.


    1. Expert Member
      MALCOLM TAYLOR | | #16


      You don't seem to understands what they are saying. Sawing the materials may produce those effects while the material is being sawed. They are worried about the workers doing the sawing, not the future occupants. Once the work is done there are no residual effects.

      I suggested looking at the work CMHC has done on the subject because they have built units especially for occupants with chemical sensitivities and intentionally used galvanized ducting

      I know being environmentally sensitive is very difficult, in part because often you aren't believed. I'm not in that camp. I completely understand you experience symptoms from being in contact with certain materials. However I don't think it's helpful to ascribe risks to things based on a misinterpretation of the MSDS sheets.

    2. Expert Member
      Michael Maines | | #18

      I'm with Malcolm. I have worked with people who have MCS and I know how challenging it can be. I don't discount your experiences. That said, the warnings listed are definitely for the workers installing it or others in the immediate vicinity, not the occupants.

      There is a small amount of manufacturing oil on the sheet metal that can be cleaned with vinegar; that may help. It's highly refined, basically mineral oil, but it leaves a greasy residue and likely contains some VOCs. The "suspected of causing cancer" is unique to California--everything is suspected of causing cancer until proven otherwise.

      What are you using for a heat source? All-electric or a petroleum product?

    3. this_page_left_blank | | #25

      "Although these symptoms can be debilitating, MCS is not recognized as an organic, chemical-caused illness by the World Health Organization, American Medical Association, nor any of several other professional medical organization.[3][4][non-primary source needed] Blinded clinical trials show that people with MCS react as often and as strongly to placebos as they do to chemical stimuli; the existence and severity of symptoms is seemingly related to perception that a chemical stimulus is present."

      I'm sorry to say, it's most likely in your head. I don't think it's helpful to be reinforcing these delusions and telling everyone with the same affliction to avoid a material which, as long as you don't plant the seed in their minds, isn't going to harm them. Sheet metal is already in the vast majority of HVAC systems in North America, both in homes and commercial buildings. Having a "sensitivity" to it is going to be a pretty debilitating.

      1. Expert Member
        MALCOLM TAYLOR | | #26


        This is the approach I take. I wouldn't accept a client who wanted me to address their complex chemical sensitivities because I don't have the knowledge to do so effectively - and I have no way of gaining that knowledge, or of usefully evaluating the information on the topic that is available.

        That said, there are some common-sense inferences anyone can make about some building materials. If these materials are going to cause an allergic reaction there are only three mechanisms by which that can occur. They must be inhaling, touching or ingesting something they have a reaction to. If something does not off-gas, and the person has no physical contact with it, then surely it can be said not to be problematic.

      2. gimmecleanair | | #28

        Trevor Lambert,
        That is utter rubbish. That's like saying that there is no evidence that cigarette smoke causes cancer. Which by the way was the position of Big Tobacco for decades. In 1964 the U.S. Surgeon General published a report saying that cigarette smoke is hazardous and causes cancer and emphysema. (Often the government takes a long time to accept the scientific reality because of industry influence. See for example the USEPA, USFDA, USCDC, etc.) Despite that the denials by Big Tobacco continued. All the while they knew that their product was hazardous. They continued the campaign of misinformation, disinformation, and spreading doubt. A document from Big Tobacco that came to light in a lawsuit said, "Our product is doubt." Doubt as to the health hazards of their product.

        Finally in 1998 Big Tobacco and Congress agreed to the tobacco settlement, which required the companies to advertise about smoking and post warnings on cigarette packages. In return, they received immunity from liability for damages due to smoking. The attorneys general of many states had sued the tobacco companies for the hundreds of millions of dollars (or billions) that the states had paid out over many years in state health care to people whose health had been ruined by cigarettes. Not only did it take 34 years from the time of that Surgeon General's report until the tobacco settlement, but it was only in response to the financial pressure of the lawsuits and not because of the scientific facts that Big Tobacco settled. They had remained in denial, parroting lies such as your lies about chemical sensitivity, for that long and only changed course when it was in their financial interest to do so.

        There are people all over the world who suffer from chemical sensitivity. Their symptoms and degree of sensitivity differ, of course. Same as people's sensitivity to aspirin or food allergies or other allergies. It is not imagined or made up. No it is not "in their heads". It is real. Your denial is in your head and comes from your ignorance.

        There are companies that test furniture, for example, by putting a piece of furniture in a test chamber, letting it sit there and off gas for a certain amount of time, and measuring the concentration of formaldehyde and other pollutants in the air in that test chamber at the end of that test period. This is a good way to test for whether a piece of furniture is going to pollute the air in a home or office.

        You are wrong about sheet metal being in the vast majority of HVAC systems in North America in homes. No it is not. The vast majority of residential HVAC systems in the U.S. are flexible plastic. I talked to about 10 different HVAC contractors last Summer (and earlier) and learned this. Your "knowledge" is so far off.

        Good luck to anyone dealing with this issue or potential issue.

  15. user-2310254 | | #17


    Were the ducts sealed with mastic? Is the attic vented or sealed? If the attic is vented, are the ducts insulated?


  16. ecodude | | #19

    Will first, don’t do your typical HVAC engine with ducts... It’s unhealthy and a poor choice for heating a home...go ductless, radiant heat panels, water or heat pump!

    Black pipe may be what you need to look at? Copper or polypropylene. Better then pex and recycled after its use ...My choice!

    Look for Lead free joint materials with less than 0.20% lead...

    Use Pex - polyethylene note: pex can leach mtbe - a toxic petroleum byproduct. A 2009 study found it leaching declines rapidly over time? Hmm? There is a safe pex-A of the 3 types of pex!

    ****PE-RT safer plastics-is pex-like pipe with out the cross-linking see; “legend” company on the web! Hyperpure

    Another; black pipe or ABS, easier to work with, but check with code officials first? 1 Caviat; made with BPA bisphenol A. 😖yak, but apparently food and drug assessment is safe.. not sure if F&d is our friend?

    Hope this helps-

    1. JC72 | | #27

      "Use Pex - polyethylene note: pex can leach mtbe "

      Be careful with parroting such claims as they arguably were made by parties who had an incentive to prevent the adoption of PEX in the state of California.

  17. ecodude | | #21

    I also work with chemical folks, and I will say what manufactures tell you isn’t the whole story... most, if not all metal ducts use a petroleum oil that’s rubbed on the metal as protection? Which is why some folks may have issues with the petroleum? I’ve had had to clean that oil off of every section before installation!

    1. Canary | | #30

      I see that you work with chemical folks. Do you have any suggestions for non-toxic air conditioning ductwork? I have tried to find metal ductwork installers in my area but they only want to work on commercial properties. I have contacted several sheet metal manufacturers that actually make the ductwork in my area without success in finding a referral to an installer.

      1. gimmecleanair | | #32

        Canary check out my reply just now. You may be interested in it.

        Good luck with this!

  18. gimmecleanair | | #22

    Robert and Michael I have a heat pump and yes it is electrical only.

    Malcolm to put it briefly the MSDS is incomplete and they are intended to provide information for workplace use, not home use. I did not misrepresent anything. I don't think you are paying attention. The MSDS is a poor and incomplete source of information for a home owner.

    Steve the attic is vented, as I think every attic is, at the eaves. Also there are 4 eyebrow vents.

    Robert the contract for these metal air ducts said there will not be any sealer, spray or coating on the metal. The purpose of that is to prevent the contamination or pollution of the air in the attic, the house and the ducts. Well, unfortunately the ducts did contaminate and pollute the air. Badly. It's cold in California now but I am healthiest now in my "outside office" (in the back yard) until I get this all fixed.

    Are you saying there are black pipe or Copper or polypropylene air ducts? Or are those for water? Thanks for your info.

    1. charlie_sullivan | | #24

      The issue of sealing the ducts is a knotty problem. Finding a sealant without chemical sensitivity issues is hard. And at the same time, leaving them unsealed means you are mixing attic air with the air in the ducts, and the attic air is likely contaminated in multiple ways that could cause issues.

      You could consider seamless ducts, and systems with tight sealing joints that don't need sealant. And use materials such as hdpe or aluminum that might be known safe for you. It can get tricky because some nonstandard materials could raise building code approval issues. But I would also consider a ductless system. Ductless minisplits are the standard option, but hydronic systems would allow you to more strictly limit what materials you bring into the living space.

  19. Canary | | #29

    Did you ever find a ductwork system that works for your health? I am presently researching changing our ductwork and having a difficult time finding something non-toxic. All suggestions appreciated. Thank you.

  20. gimmecleanair | | #31

    Evan & Suzy,

    I am curious too. DId you find a solution, a type of duct work which is good for your health and does not affect the air quality in your house?

    As ecodude said, what the manufacturers tell you isn't the whole story. They probably tell you what they are required to tell you. And no more.

    As Evan & Suzy said, " We don't have the toxicity information we need because no one's ever tested it. When toxic injury comes on imperceptibly, incrementally, one would not notice, then... bam. Of course the medical establishment won't have a clue unless one connects with a chemical injury physician, a growing profession these days. No one's tested any of these duct products for long term accumulation of poisons therein so there is no data."

    Here is what I learned from my experience, which I described in my post on February 25, 2021.

    The stainless steel air ducts, with no coating of oil, installed without mastic, was a BIG air quality problem. I don't know how or why but my experience was this. The night before the installation I slept fine in my house. My sleep has always been susceptible to indoor air pollution ever since I became chemically injured and sensitive in the summer of 1993. The night the installation was finished I could not sleep AT ALL. Something had radically changed. The new air ducts, as installed, were polluting the air in my house and ruining my sleep.

    I hired a professional to take some air quality samples and test them for metal particulates and volatile organic compounds. The test results were what I would call negative. Minimal amounts of vocs and metals. Nothing which would be expected to cause a health problem or pollute the air. The mechanism, how the air ducts ruined the air in my house and my sleep, remained a mystery.

    Eventually, thankfully, the problem went away. I became able to sleep in the house again. I would say something changed in the air quality in the house. Something offgassed or dissipated or the chemical reaction(s) stopped happening, whatever they were. Subsequently I have had other huge problems with indoor air quality unrelated to the duct work.

    Based on all of this here is what I would recommend. Get stainless steel air ducts but the key will be to let the steel sit somewhere for at least six months. Then bring in the contractor to install them. Whatever off gassing or chemical reaction(s) need to occur will occur but not in your airshed. Leave them in the garage or a tool shed. Or outdoors. Doesn't matter. If I could do it all over again I would do this. Actually I would never have removed the old flex ducts in the first place. They were dusty on the inside. There are companies who clean air ducts. I could have called them, spent a few hundred dollars to have the air ducts cleaned, and life would have been good. No indoor air pollution from dust or from the materials in the flex ducts and stainless steel ducts which I later bought.

    If anybody tries this please post your results here.

    Good luck to everybody dealing with this, whether you are a home owner or contractor or green building advisor.


    1. Canary | | #33

      Thanks for your insight. I cannot find anyone that installs metal ductwork in a residence. They only work with flex unless it is in an office building or hospital. I have watched videos of metal ductwork installation and they use Mastic on them. Could it be whatever they used to seal your ducts instead of Mastic bothered you?

      1. gimmecleanair | | #36

        Canary I know what you mean. Same thing in this area, Sacramento. Metal is usually used only in commercial. I had to ask several companies to find one who would install metal. I'd say if they have the experience installing metal in commercial then they can also install it in residential. It's the same product installed the same way. I made it worth their while, agreeing to and paying them about twice what flex ducts had cost me in 2019. In place of mastic they used sheet metal screws and the aluminum tape, and I don't think either of them had any effect on the air quality. I think it was something about the ducts themselves. By June 22 of last year though (less than 6 months in) there were no metal or VOC pollutants of any significance in my house, as the air sample evaluation showed.

        1. Canary | | #37

          I have called numerous ac companies, an ac technical school, the local sheet metal manufacturers for a referral and Monday I am going to try the local union. No one wants to work in residential attics thus far. I am willing to pay more and I am guessing twice the price. "This Old House" has a You Tube video I watched on "tin knocking". They used metal screws and aluminum tape but also mastic.

        2. TrueFeedback | | #41

          Hi Mark,

          I really appreciated you sharing your personal experiences with different types of ductwork. I have done some deep research on my own and also talked to HVAC experts, and mold experts in the fields. I have found consistency with your experiences on flex and galvanized steel ducts. Again, thanks a lot for your information. We choose the real stainless steel 304 ducts, even though it means to cost more money. But it will be great for our family's health.

    2. Expert Member
      MALCOLM TAYLOR | | #34


      Why six months? Why not six weeks or six years? Where should the ducts sit? Will they maybe pick up some other detrimental problem there?

      As I've said earlier in this discussion: I'm not in any way dismissing or trying to minimize the symptoms you experience, but the solutions being proposed are entirely random. There is no more basis for them than asking a wizard to come in and sprinkle fairy dust on everything.

    3. TrueFeedback | | #42

      Hi Mark,

      I really appreciated you sharing your personal experiences with different types of ductwork. I have done some deep research on my own and also talked to HVAC experts, and mold experts in the fields. I have found consistency with your experiences on flex and galvanized steel ducts. Again, thanks a lot for your information. We choose the real stainless steel 304 ducts, even though it means to cost more money. But it will be great for our family's health.

  21. gimmecleanair | | #35

    Malcolm Taylor,

    Several mistakes in your message. The first is your failure to appreciate what I am doing, which is making recommendations which, based on my experience, I believe could help a person with chemical injury and sensitivity deal with metal air ducts. The second is your apparent inferring of a guarantee in my advice. I neither said nor suggested I would (or could) guarantee good results. The third is you have apparently never heard of off gassing. People with MCS know ALL ABOUT off gassing. It's how toxic building materials including carpeting get into the air. It is very common and very well known. You could look it up. There is nothing random about what I said.

    Where should the ducts sit? Read my message. I addressed this.

    Why six months? In my experience it was something like 6 months before I was able to sleep in my house again after installation of the new metal air ducts.

    If somebody wanted to try letting the air ducts site before installation for 6 years, go for it! It's probably unnecessary. Why do YOU think they should wait 6 years?! Please explain this.

    In my opinion 6 weeks would probably not be long enough. Given the stakes, which as you can see from the OP are VERY high, it's better to err on the side of more time. When it comes to off gassing time IS on our side.

    What solutions do you have? I haven't seen you recommend any. Easy to criticize, especially when you do not really read and understand and think about the message you are criticizing. A little more difficult to offer an actual workable solution. Try it.


    1. Expert Member
      MALCOLM TAYLOR | | #38


      Go back and read my previous posts. In #10 I suggest looking a the work CMHC have done around building for chemically sensitive clients. They actually look at the science and experience of the sufferers when trying to find solutions.

      In -post # 26 I explain why I don't suggest solutions myself. I'd much rather be accused of inaction, than just making stuff up, which could give false hope.

      This is a complex topic which you want us to take a position on and give you comfort and support. You have a kind of "Are you for us or against us" stance. I think that's unhelpful, as is suggesting solutions based solely on how your health declined or improved, which may have had absolutely nothing to do with what occurred in your house.

      You have at best a poor understanding of the basic mechanisms (like off gassing) at play. You don't know what you are trying to eliminate from the ducts, or whether leaving them for a period will achieve that. I was just just pointing that out.

      1. gimmecleanair | | #39


        Do you really think you are helping anybody by the stuff you write? What a joke. What a total joke. You are not speaking from your own experience. You are reasoning from the general to the specific, a specific situation involving real people. Which is one reason you are wrong.
        There's not one bit of anything useful in anything you wrote. If you would pay attention to what I wrote you would have a good idea what happened to my health and my house but you have failed.
        And you have no idea. I understand off gassing very well. You don't. If you had anything useful to offer about off gassing you would ACTUALLY WRITE IT HERE. Instead you sit there and claim I don't understand off gassing and you claim you do. Well prove it. Do you see how silly you are? My understanding of what happened here is infinitely better than yours. Too bad, kid. You're the last person anybody with MCS should turn to.


  22. DavidDrake | | #40

    Hi Mark,
    I'm a little confused. In post #13, it seemed clear, based on the SDS you referenced, that hot-dipped galvanized sheet metal was the material used for your ductwork. However, in post #31, you twice referred to the ductwork as being 'stainless steel.'

    Is it possible your contractor neglected to clean the manufacturing oils off the ductwork before installation? Or that you have a sensitivity to the adhesive used in the aluminum tape? Or that you were exposed to some other substance more or less at the same time the ductwork was installed?

    Reason I ask is, it just isn't possible for clean galvanized steel or clean stainless steel to off-gas anything, at least not at temperatures less than 800° C or thereabouts. Metals are not organic compounds, and neither steel alloys nor zinc volatilize at air temperatures survivable by humans.

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