I have worked as a green materials specifier for the last eight years, mostly for folks who have an environmental illness like multiple chemical sensitivity, asthma, or lung disease. I, too, am chemically sensitive, which helps inform my work.
The biggest challenge with making recommendations in this field is that most companies do not reveal the exact chemical composition or volatile organic compound (VOC) levels of products and materials. Even if a product is approved for green-building-certified projects, it is not always clear if the product is zero-VOC or comes in at the highest level allowed. And, even with materials that state a VOC level, unless the product is zero-VOC, there’s no information on when off-gassing can be expected to end. This is a big challenge for those wanting to reduce the overall VOC levels in a home. Only a few common materials have been studied academically, and it’s in obscure journals that their off-gassing rates and timelines can sometimes be found.
When documented VOC levels aren’t available, some of my recommendations come from having sampled myriad materials within a category and from the experience of chemically sensitive people. However, anyone interested in lowering VOCs in their home can obtain a dozen samples of, for example, nylon carpets and a dozen samples of polyester carpets, and it would be apparent which has the least odor.
Of course, not all chemicals of concern have odors. For those chemicals, it’s necessary to go by manufacturers’ claims. But the reality is few organizations are conducting independent oversight to verify a product is truly free of semi-VOCs like PFAS, phthalates, heavy metals, or flame retardants.
A bit about off-gassing rates
First, what is reasonable?
The graphs below show the off-gassing rates of formaldehyde and hexaldehyde (with different humidity levels). Off-gassing…
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I really appreciate the work you are doing and this summary. Too often when people show up in the Q&A here with chemical sensitivities, we don't have good answer for them, and this can be a good starting point. And there's more on the website noted in the bio at the end.
Those of us who don't have obvious chemical sensitivities would probably be well advised to follow these guidelines to some extent too--even without obvious symptoms, minimizing toxic materials in your house can only be helpful to you, future residents, installers, and people exposed to the manufacturing environment.
I agree. This is a logical and useful guide on a subject that can be very contentious.
One question I have is whether it's possible to encapsulate some of the problematic materials so that they no longer off gas at levels that may cause reactions? Are there coating you can use on say particle board to do this?
Hi Malcolm, technically you can encapsulate anything but rubber with either shellac or a water-based sealant. But in most cases it is going to ruin the look of the finish.
Shellac, whether waxed or de-waxed is definitely the best seal of VOCs and odorants. That is the type of primer that is used to remediate smoke and fragrance as you probably have seen but it's the pure shellac that works just as well and is a healthier alternative.
The thing is shellac is shiny, not as durable as other coatings like floor coatings, and even the lightest ones are a bit yellow in my experience.
The water-based sealants are the ones from AFM Safecoat which are not quite as effective as shellac but may work better in the end (due to not being as shiny or yellow) on certain substrates.
I haven't used it for this purpose, but if you buy shellac flakes and dissolve them in alcohol yourself, you can select "Plantina" or "ultra-blond" grades which have pretty minimal yellow tone. For example, from here. https://www.shellac.net/dewaxed_shellac.html.
Of course, if you can hide the sealing layer behind something else, a layer of aluminum foil would beat any sealant.
According to a phrase you wrote in this article, your topic is "my list of the 10 most concerning building materials." Fair enough. It's a useful list.
That said, the title to this article is misleading. (It's possible you didn't write the title.) Those of us who report facts need to be careful using the word "toxic," which means poisonous. Lead and asbestos and cigarette smoke are, arguably, toxic. But it is irresponsible to call the building materials you list "toxic." It's an alarming word that doesn't advance understanding of the health issues you intend to raise.
Hi Martin,the original title was "the most toxic...." but in official agencies and documents that I read the VOCs, semi-VOCs would be considered toxic. For example, the CDC says:
"Formaldehyde is a highly toxic systemic poison that is absorbed well by inhalation. The vapor is a severe respiratory tract and skin irritant and may cause dizziness or suffocation."
So then it comes down to the dose of course for VOCs.
The way that I use the term toxic is really in that same general sense, without being dose specific. But the way I learnt the term "non-toxic" that is often refers to the dose, so saying "x ppm of formaldehyde is non-toxic" or plywood is non-toxic [because the formaldehyde quickly reaches non detectable].
I guess you could say the title would be more accurate if it said toxicant-containing materials? But that might be too awkward. I'm open to the title changing, I know you are an editor here.
I'm retired, so I'm only offering a personal perspective. Formaldehyde is, indeed, toxic--but that doesn't mean that the ten listed building materials are toxic.
I'm fielded lots of questions over the years from alarmed homeowners who want to rip out materials because they've heard that "x material is toxic" (usually followed by an exclamation mark). Even when materials aren't actually toxic, anxiety can create medical symptoms. Those of us who educate homeowners and builders need to be careful with our language.
I totally agree with causing alarm and stress and that stress could be easily more harmful than a very tiny amount of formaldehyde (my opinion of course). I try to offer the information without dictating what people should do. I think all of the substitutions here are absolutely worth the effort of making.
One of the line items was engineered woods with formaldehyde, so the "toxin" or toxicant is the chemical that is offgassing from it. The others are similar in the way they are described.
Ok sorry for the misunderstanding about the editor status. I'm so happy to be contributing to GBA and spent many years reading your posts.
I think you are in error Martin. My understanding is that biologists use the term toxicity to mean a dosage level that causes harm to a living organism. So I guess a poison is certainly toxic, but a toxin is might not be terribly poisonous.
I found the article helpful and informative. Those of us who work in the industry have higher levels of occupational exposure to all these toxins and poisons, some we know about and probably many we don’t. I am always grateful to those who work toward my health and safety.
A substance like formaldehyde can be toxic without a building material that was manufactured with formaldehyde being toxic. My objection is to the title referring to toxic building materials.
Thanks, this is a great topic. I have learned the hard way a few important lessons in this regard:
Don't Ignore safety: In the 1970's I was a house painter. In those days, we ignored safety precautions: scraping lead paint and asbestos siding. We refused to wear masks (sound familiar?) and worked in shorts/tee shirts. We often were covered with solvents, thinners and oil paint until we could taste them on our tongues. I quit at a young age, but many others did not and quite a few died young.
Building Products are not all well tested: When I quit painting I became a lawyer and quickly learned about toxic substances. As a law clerk, I worked on a huge class action case representing the Urea Formaldehyde Foam Insulation (UFFI) industry. Somehow UFFI was deemed safe by the industry and thousands of houses were sprayed until people began getting sick and blaming the foam...In response, the industry suggested that perhaps it was because houses were too tight : they suggested that claimants keep their windows open (!).. Many companies were eventually bankrupted and the the spray foam industry was forced to move to different blowing agents and binders. However, this taught me that building products are not always well tested for health concerns before they are put on the market.
Some products don't mix/People can become sensitized easily: Much later in life I learned that even relatively safe products can be dangerous if mixed together and that some people can become sensitized to relatively low levels of many chemicals..... After Hurricane Sandy flooded my dad's home, mold on my dad's ground floor CMU foundation walls were removed with a Phenol based mold cleaner (sporacedin). Years later when the mold reappeared, we used the same cleaner. However, shortly thereafter, someone spot cleaned with another cleaner bought at HD (I believe a bleach based cleaner). Somehow this mixed with the chemical residue on the walls and created noxious fumes that caused us to evacuate the floor. The smell lingered for years and I would have a reaction (puffy tingling lips and stomach upset) every time I entered the space. I tried to scrub it off, covered it with AMF Safecoat, kept dehumidifiers going and huge fans etc. to no avail. Everyone else thought I was nuts so five years later I finally took my Hilti and ripped out the entire CMU wall and replaced it! Only a tiny bit of odor remains......But even now, I don't like new cars because that new car smell....is from the phenol in plastic interior parts.
How effective are 24/7 balanced ventilation systems like HRVs and ERVs at mitigating VOC levels from materials either built in to a house or from things like furniture, assuming that the system is doing .3 ACH? Any articles or studies on that?
Great question, particularly for very tight houses. I would also like to know if the system itself adds to VOC's depending on what the duct work is made of
Looks like there have been some studies done on this:
The effect of ventilation on volatile organic compounds produced by new furnishings in residential buildings
• Research identified & quantified VOCs generated in timber-framed unoccupied houses.
• Some chemicals were detected at high concentrations in background samples.
• Increased airtightness delayed concentration maxima and decay rate was slower.
• Measured internal TVOCs (as toluene) were 74–90% higher in the absence of MVHR.
• Concentration reduction to below TVOC guidelines required 9 days of MVHR operation.
LBNL: Ventilation Control of Volatile Organic Compounds in New U.S. Homes: Results of a Controlled Field Study in Nine Residential Units
• Low-weight aldehydes and VOC concentrations tended to decrease as the air exchange rate was increased. Generally, concentrations were reduced significantly when the air exchange rate was above about 0.4 ACH.
• The dependence of indoor concentration on the air exchange rate timescale was linear for most compounds with concentration proportional to 1/Nh. For a subset of compounds including formaldehyde, however, the indoor concentration exhibited a non-linear dependence on air exchange rate, consistent with a concentration-dependent emission rate.
I suspect it would be hard to quantify the effect as there are so many variables. As a general strategy what is usually recommended is a threefold approach: Removal, encapsulation and dilution - with ventilation being the driver of the latter.
Seems like it would be possible to turn off the ventilation in a very tight house for a while, measure the VOCs, turn on the ventilation system back on and measure again, then repeat?
I'm surprised if those kinds of experiments haven't been run yet. Perhaps I'll try it in my house.
That makes sense. I thought y0u meant how effective was the ventilation in houses in general, as opposed to a snap shot of a particular house at a certain point in time.
I suppose I'm interested in both the general question and the specific. The studies I linked above seem to suggest that ventilation works, but most effectively above o.4 ACH
In my experience, dilution is far more effective than air purifiers.
It may be a useful rule of thumb, but I'm still not there with the general assertion that 0.4 ach ventilation in any tight house will effectively mitigate levels of VOCs. It ignores variables such as the levels of off-gassing occurring, the differing levels of ventilation rooms in a house (even with a well designed system) experience, the proximity of the materials causing the off-gassing, occupant behaviour, and external pressure differences. I think the effectiveness in any particular case is going to be very situation dependent.
There are also some contaminants that don't respond to ventilation. From BSC:
"Some contaminants do not respond to dilution ventilation at the rates we typically deal with in houses. Formaldehyde is a case in point. At ventilation rates less than 0.5 air changes per hour (ach) there is no correlation between ventilation rate and concentration (Figure 1). As air change is increased and formaldehyde concentrations are reduced by dilution emission rates are simultaneously increased.
Very interesting article. Two small comments:
1. While I agree that the nose is very good at detecting objectionable smells and nobody wants a chemical smell in their house, odor is a very poor indicator of "toxicity". Carbon monoxide has no odor but can kill you. Eggs smell like sulphur but are good for you.
2. With regard to foam (full disclosure: we are a foam contractor), open cell foam has the potential to smell when off-ratio due to an amine catalyst. I am unaware of any odor issues with closed cell foam. The EPA regards foam insulation as "relatively inert".
There are volatile chemicals that are odorless, like radon and carbon monoxide but most VOCs of concern in homes have an easily detectable smell.
Sulfur is harmful in high amounts, the so-called "Chinese drywall" debacle was over sulfur from drywall. (Something that could have been identified by someone sensitive like me.) It's similar to formaldehyde in that way, natural and fine in low amounts, not good in high amounts.
Every consideration simply is unimportant if you spray foam your house esp with closed cell. What a crap shoot…you are expecting an uncertified guy with GED to master-or even care about-the intricacies of the chemistry of mixing this up on site? I’m never cease to be amazed to see how many expensive homes take this gamble. I’ve been in multiple attics where it looks like Luray caverns and smells to high VOC heaven-some up to seven -7- years old. You don't have to be a chem phobe to avoid this crap. And don’t tell me ‘my vendor does a great job’ - how would you know?? ‘ have you been trained certified> ?do you do sophisticated air toxins analysis after application, etc…? ; I cant believe how many people I see sweating the formaldehyde content of the desk they bought from ikea and are oblivious to fact they have enclosed their house with spray foam…inspectors dotn even go into the attci most times to inspect install, and if they did what was the last tiem you saw them make contractor pull, it all out for toxic smells, AND lets get real-when was the last time you saw them pull it out in any case?thsi product should be highly highly regulated instead allowing manufacturers to franchise guys with no training to run out there Nd do their moonshine number and share 7 dollars a sq foot/inch. I can believe we regulate nail salons more highly than spray foam installers, but then again that’s the corruption and juice at state level building contractors have. At least the car dealers are subject to federal regulation of automobiles they sell thank god.i won’t dispute that modern foams when applied properly by competent factory trained careful and professional installers solve SO many problems in insulation g modern house, and lets stipulate bad jobs represent say !10, or even 1 per cent of teh industry. If you roll the dice and get Thsi wrong, or installer had a beer o. Way to your afternoon job, what other insulation runs t risk of making the house uninhabitable unless you gut it ? Actually even worse-you will have to remove all the roof AND the rafters-WHY TAKE THIs RISK just to make installers job quicker and more lucrative ??
I only recently stumbled across this article, so hoping the comments section is still open!
I'm curious if you can comment on the toxicity and/or safety of plumbing piping -- Copper vs. PVC vs. PEX, etc. Do the latter two contain plasticizers? Do they leach into the water? Does it make a material difference if it's hot vs. cold water being transported? Etc.
I do have an article on pipes on My Chemical Free House. In short, comparing PEX to copper for incoming pipes is comparing two totally different toxins. I'm very biased because I had copper toxicity, others worry more about the leaching of chemicals from PEX. There isn't an objective way to say which is worse. Both can be filtered out however, so that is good news.
I am trying to find 3rd party information about formaldehyde in engineered framing. It is being used more and more as quality of lumber is degrading. It was less expensive than dimensional lumber during COVID. Can you point me to a good resource? Thank you!
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