Blog Post

EPA Raises Health Concerns with Spray Foam Insulation

Spray-polyurethane foam (SPF) insulation, growing in popularity, is under scrutiny from EPA. What's a homeowner or builder to do?

Originally published May 16, 2011. Updated by Paula Melton June 1, 2018.

A friend of mine used to be a long-haul truck driver. At one point he even became a trainer working with new drivers.

Over dinner recently, I asked what was one key lesson that he would want to impart to any new driver. While he was thinking about it, his wife lit up and offered this advice (which I'm sure is not from the company manual): make sure your seatbelt is removed before you begin a hot swap.

In trucking, a hot swap occurs in a truck being driven by a team of two drivers when they are in a real hurry to make a delivery. When one is ready to take a break and turn the wheel over, rather than taking the time to stop, they may decide to trade places while the vehicle is moving down the highway.

Hot swapping green building techniques

While I'm sure that experienced drivers can "hot swap" quite, um, professionally, it is an inherently unsafe practice. This is underscored by the fact that you have to remove your seatbelt, in a speeding tractor-trailer, before you can even begin!

When I heard this, it felt to me a lot like a situation we face with some regularity in green building. We are racing to make our buildings safer, healthier for occupants, less-polluting, and lower carbon. But we are behind in that race. For example, we have been paying serious attention to the health effects of building materials on indoor air quality for only about 20 years. We have been inventing new chemicals that affect our indoor air quality for well over 100 years.

Unfortunately for the builder, homeowner, or renter who simply wants some reliable advice on what to worry about from an environmental perspective, and what not to worry about, things sometimes change or crop up unexpectedly. And we're not usually completely ready with a seamless hot swap. Remember when compact fluorescent bulbs first came out? Remember the first low-flow toilets? Best forget them.

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The issue of the day? SPF safety

The issue of the day is spray polyurethane foam (SPF) insulation products. Last month the U.S. Environmental Protection Agency (EPA) released a new action plan for a key family of chemicals used in SPF. Isocyanates, such as MDI (methylene diphenyl diisocyanate), are chemicals that react with polyols to form polyurethane. They can also cause skin, eye, and lung irritation, asthma, and chemical sensitization when absorbed through the skin or inhaled.

Polyurethane is in a lot of stuff, from foam mattresses to bowling balls. When it is fully reacted or "cured," it is stable and its chemistry is not a significant concern. However, Some products, however, such as adhesives, coatings, and spray foam, react while being applied by builders or homeowners doing insulation retrofits, and continue to react for some hours afterwards, and may contain "uncured" isocyanates to which people may be exposed.

This is not news: worker protection protocols and quality assurance programs for SPF installation were developed by the SPF industry decades ago. Why the fuss now?

Why the fuss now?

As Steve Owens, assistant administrator for EPA's Office of Chemical Safety and Pollution Prevention, put it, "There has been an increase in recent years in promoting the use of foams and sealants by do-it-yourself energy-conscious homeowners, and many people may now be unknowingly exposed to risks from these chemicals." You can add to that a growing number of complaints about adverse health effects from homeowners and occupants of office buildings where SPF has been applied during energy retrofits.

EPA's SPF action plan for MDI is being developed within its Design for the Environment (DfE) program under jurisdiction from the Toxic Substances Control Act (TSCA), which requires U.S. chemical manufacturers, importers, processors, and distributors to report to EPA any information suggesting that one of their chemicals "presents a substantial risk of injury to health or the environment."

While the reported data is technically public information, penetrating it is very difficult, in some measure because manufacturers often claim confidentiality for proprietary components in their chemical formulations. But the cumulative evidence to date has moved EPA to take real action on this issue, mainly to gather reports of adverse health effects from manufacturers, and to consider initial rulemaking for both consumer-applied and professionally applied SPF products.

The action plan leaves open questions about how far EPA will go to clamp down on these products, but it's safe to think of this as a shot across the bow from EPA for the SPF industry.

We don't know much about SPF offgassing

In addition to the presence of MDI in the product, the chemical reaction and curing of SPF can produce other chemicals of concern: excess isocyanates, aldehydes, amine catalysts, and other volatile organic compounds (VOCs). We don't know much about the nature and quantities of offgassing of these substances, the curing rates of SPF, or how health risks can change with improper environmental conditions or mixing ratios during the SPF process.

To that end, there is a new ASTM standard under development. John Sebrowski, a senior associate scientist with Bayer MaterialScience and chair of the task group working on this ASTM standard, is helping develop a standard practice to establish re-occupancy times after onsite SPF application. "We are currently getting ready to conduct research using micro-scale chambers and thermal desorption techniques to measure emissions," he said.

Safe re-entry times

When asked what relationship the current ASTM draft standard and research might have to the existing protocol offered by Bayer MaterialScience (which recommends re-occupancy times of 12 hours and 24 hours for workers and occupants, respectively), Sebrowski responded that the protocol would be used as a starting point, but "we are also investigating other approaches to measuring the emissions."

According to EPA, safe re-entry times put forward by manufacturers vary between 8–24 hours for one-component SPF and 23–72 hours for two-component SPF. But more research and standardized testing is clearly needed. EPA is not working alone on this issue; several other federal agencies--including the National Institute for Occupational Safety and Health, the Occupational Safety and Health Administration, and the Consumer Product Safety Commission--are part of the team. Each is concerned about protecting workers or consumers from health effects from the increasingly prevalent site-applied SPF.

Should we stop using SPF?

spray foam insulation

Installing spray foam insulation.

"I think you have to be careful when you discuss the toxicity of spray foam," says David Price, environmental scientist in the indoor environment division of EPA's Office of Air and Radiation. "I have not seen any information at this point that there is any hazard to occupants." While Price supports EPA's decision to gather data on possible post-occupancy issues with SPF, he doesn't want the public to "find the accused guilty before you hear the case."

Price has seen some of the anecdotal evidence as well as some of the scientific findings, and says that no cause-effect relationship has yet been found between SPF installation and post-occupancy illnesses. "It's appropriate for EPA to look at this stuff; that's what we do," Price said. "But I'm very sensitive about tagging a product as 'of concern' or 'may be toxic'" before the data has been gathered and reviewed.

Environmental Building News contacted several builders and foam industry professionals, and found that most were unwilling to be quoted on an issue they deemed sensitive and still-unfolding. One leading green remodeler offered this perspective: "I have stopped using SPF in any of my projects at this point. I simply can't and won't jeopardize my clients' health and the reputation of my company by using building materials with the emissions profile of SPF."

Since this news came out, comments on message boards that I have seen have tended toward defense of SPF and annoyance (that's putting it politely) at EPA. The undercurrent seems to be: Is the whole industry going to get stained because of some untrained DIYers? Let's hope that the general public doesn't jump to conclusions too rapidly--that EPA gathers its data and that its process works. And let's be real: not all SPF insulations jobs are perfect--some have even ended tragically.

Recommendations for continued use

SPF has unique advantages that can be difficult to replace. If you decide to continue using it while EPA continues its work, here are some recommendations.

Also, stay tuned; the SPF industry is working on a new class of SPFs--hybrid non- isocyanate polyurethanes (HPINUs)--that may pose much less serious occupant and worker health issues than our current slate of SPF building products.

What do you think about the SPF issue? Do you use it, or not? Why? Let us know below.

Note: Peter Yost, Vice President, Building Performance, and Paula Melton, Research Associate, contributed reporting to this column.

Published June 1, 2018 Permalink

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Comments

October 17, 2019 - 12:18 pm

I cannot thank you enough for answering my questions! 

October 17, 2019 - 12:14 pm

Kasey, there is no indication that isocyanates cause cancer.

October 17, 2019 - 12:10 pm

Thank you! Are the chemicals also carcinogens? I am worried about the asthma part also. 

October 17, 2019 - 10:58 am

Kasey, consider posting your issues on Green Building Advisor, which specializes in single-family residential and has a community of experts who will likely have good advice for you.

October 17, 2019 - 10:56 am

Hi, Kasey! I'm not a building science expert, so I'm not sure how much the attic fan would help. However, I would be concerned with the lack of ventilation in the bedroom even without the smell. Isocyanates from spray foam are an asthmagen, meaning they can cause asthma in otherwise healthy people, so that's something to keep in mind as you consider.

October 17, 2019 - 10:12 am

It’s hard to describe. It is slightly fishy. Originally I thought it was a pee smell, but it’s definitely not. Another concern with the room is that there are NO windows in the room. So there is no ventilation at all. 
 

Removing all of the insulation is not really an option as it is very expensive. Would an exhaust fan built in to the attic to get rid of the air be helpful, or do you suggest the baby not being in the room even after the exhaust is installed? 

October 17, 2019 - 9:40 am

Kasey, I'm not sure what kind of odor you are smelling. I think people usually describe a fishy odor. If that's what you've got, I would probably move the room and do some research about remediating.

October 17, 2019 - 9:18 am

We recently moved into a house that was built in 2012. The attic has spray foam throughout, only in the roof rafters and rafters around the house. There is one room upstairs that is surrounded by the attic. The walls of that room are not insulated with anything. Our 1 year old sleeps in that room, and when we moved in, I noticed his room has a certain smell. I’m concerned that him sleeping up there will effect his current and long-term health. We live in South Georgia and it can get quite hot down here in the summer months. How concerned should I be that our baby sleeps in that room? 

July 30, 2019 - 7:15 pm

Can you contact me to discuss

June 11, 2019 - 10:44 am

Hello, 

My wife and I closed on a brand new build in December of 2017. Fast forward one year- our house has an acrid smell from the attic and walls, especially when it heats up outside. Some days the smell is so overpowering it drives me crazy! Our house is fully encapsulated by SPF: from the basement all the way up into the attic (the rafters; not the ceiling deck is sprayed with SPF). In addition, we have major moisture issues in the home during the winter months, especially when the temps drop below 25f (18/21 of windows developed thick ice on the interior of the home). We've had 2 home energy audits completed, both indicate our house is actually too tightly sealed. The last audit indicated our SPF may not have cured correctly and this could be a source of moisture and the smell. I live near Denver CO, and was informed by the auditor, with our drastic climate variations (80deg one day, blizzard the next) we really shouldn't have a sprayed attic at least on the ceiling joists/rafters. Anyone else experience this issue, further, is there a company in Colorado that will test the SPF to see if it cured properly. Thanks in advance.

May 7, 2019 - 9:20 am

Hi, Diane! I'm unsure how to find out what the substance is, but rest assured that if it is spray-foam insulation, the cured product is not generally considered to be harmful. It's when it's being applied that it is problematic. Hope this helps!

May 7, 2019 - 6:22 am

Recently my son rented a Pod to move from Virginia to Colorado. When unpacking his belongings, there was a white chunky substance all over everything! He believes that this substance came don from the ceiling, which has the same stuff on it. It lloks like it was some sort of foam insulation, but, we cannot find information about what it contains or possible health hazards. It is all over the furniture: couch, child's headboard, all chairs and tables. He has small children and is concerned about any long-range health effects this substance may cause. He suffers from eczema and many allergies. How can we find and get a specialist to analyze this substance, to isolate its components. The company is very apathetic, and will not disclose the name of the product used, or the competency of workers who installed the substance. I don't know how this works, but hope that someone will contact me with information ASAP. Thanks for having this site!

April 29, 2019 - 9:43 am

Hi, J c! We would generally recommend dense-pack cellulose for a whole-house insulation retrofit. It's more environmentally friendly and also quite a bit cheaper. It does not offer the airtightness that spray-foam is known for, but it has good performance.

April 27, 2019 - 1:49 pm

I purchased an older home only to learn that the house has no insulation. Someone recommended using spray foam, however, I am concerned about the health effects. Is there an alternative product to use in the walls? Tearing down all the walls would be cost prohibitive.

December 16, 2018 - 8:52 pm

I live in Michigan, Macomb county, and I was qualified for a weathereization program and the foam insulation was sprayed in my basement without my knowledge that the spray foam was being used. My daughter and I stayed in the house unknowingly we were supposed to be out the house for hours. Now I don’t feel well and my daughter also mention that she’s not feeling well. I think it’s really sad that the county failed to inform me of the risk of spray-foam insulation.

October 7, 2018 - 6:38 am

after 7,000.00 which they said would encourage buyers this job has permeated up into home causing us to loose mattresses  with toxic taste and 5 yr old 6,000.00 leather furniture as well as some of home.  Contacted ct basement as they are avoiding truth lieing and after realizing after washing walls and floors for months within days its back and inhaling burning  throat nose and chest, even my hair toxic  I would like mail from others especially ct basement to try to form a group for government to listen to this health trap, all ct heads whom I have contacted blew me off and sent me to con protection, my husband starting chemo for cancer and house not soft with no help from government as they turn back on us. PO box 110096 for others experience

August 13, 2018 - 8:22 am

Can anyone tell how bad is it to use SPF to seal the joints between concrete rings in water well? I know one water well where it has been used over and under water level. I have been trying to find out since I found out about it has it been good or not so good idea use it as seal? I would be really thankful if someone could answer to my question and explain little why so? I have red most of the messages in here but most of them are about air exposure. Does SPF react with water over or/and under water line?

July 31, 2018 - 12:30 am

 I have been using foam applications in the hollows in floor joists in crawl spacer after encapsulating them for 4 years now or better. The foam applied properly and after curing is basically harmless and a great insulator plus sealant is various situation but not all.  Again I state proper application and knowledge how to apply the foam is crucial to its performance. All proper safety procedures must be followed while applying it.  Once it has cured again it is harmless. Chemical sensitivity is most likely to happen with a fresh application applied in a none vented area. 

June 4, 2018 - 6:48 pm

i had basement gutted in January 2017 and had spray foam applied to concrete walls. Since then I have had sinus pain, headaches, congestion, and tired. I have had MRI, EKG's, ct scan of sinuses. I have taken amoxocillan, now on prednisone. Nothing helps the pain except leaving the house. I have cleaned basement wiping down everything, had ducts cleaned, twice had quality air samples taken and no mold detected, had thermal imaging done on walls, no moisture found, gas checked for leaks, and have found nothing. I have an air to air exchange I run and also have two dehumidifiers. I contacted spray foam company and they find no reason that they have done any thing wrong. I was never told to vacate house when sprayed and wonder if that could be problem. I don't know what to do anymore. Any suggestions? Thank you. I live in Wisconsin and had spray foam applied because I had mold many years ago and remediated by company.

January 10, 2017 - 12:12 pm

While the debate and studies go on there is one form of insulation that has no off gassing, the lowest carbon foot print, biodegradable, and no chemicals added.  That is pure wool insulation.  It is relatively new to the market, but is readily available throughout the USA, and very price competitive with spray foam.

September 29, 2016 - 12:15 pm

Hi, so in a bit of pickle right now. We searched high and low to figure out what to do for insulation in our 2nd floor Cape House reno. We added a 28 ft shed dormer and didn't want to use spray foam at all for insulation. We had received 1600 sq ft of commercial grade Roxul for free (from my work) that we wanted to use and had to find a company to install it. Long story short, because cross beams were added to the interior framing before the insulation was put in, it made it almost impossible to get polyiso boards in there (over baffles), which we wanted to use before putting in the Roxul. We ended up doing baffles with 1 inch of spray foam over that (which apparently expanded to 1.5 - 2 inches says the company that sprayed it), and then installing the Roxul over that (4.3 R-value/inch) to meet code requirements.

The baffles and spray foam were put in on Monday. My husband has asthma and I am 7 months pregnant (I know I know) and even though we are still staying with my cousin since Monday (it's now Thursday), my husband says that when he has gone back to the house, he's gotten headaches from the fumes and he can smell them. He put two fans in the 2nd floor windows today and there are workers upstairs putting up drywall today. I have gone back a couple times (once Tuesday and twice yesterday) to get a few things for a minute or two, and I can't smell anything so I'm not sure but maybe he's sensitive because he has asthma?

The plan is to open all the windows on the 1st floor and to bring more fans in to circulate the air before moving back into the house. We also have two air purifiers that we'll put on when we stop by the house tonight. We are going to stay with my cousin for another night or two but have to leave her house Saturday morning as they have other guests coming to stay with them. We're looking into maybe camping in the backyard or borrowing a friends camper until the smell disapates enough that my husband can't smell it anymore.

Do you have any other recommendations on how to handle the situation?

September 29, 2016 - 12:43 pm

It might not be the SPF at all, and a lot of compounds can cause irritation below the level where you can detect their odor, so I would not use odor as an indicator (though I can't think of anything better, short of paying a lab to come test your air, and even that won't tell you much that's useful). Sounds like you have a good ventilation plan. I would judge by the asthma rather than the smell, though. And since it's a full reno ... that smell could be anything. VOCs will dissipate pretty quickly, I would think, especially with the ventilation you have in mind. Good luck!

September 29, 2016 - 2:37 pm

The smell is definitely the insulation as we had a 2 week break beforehand and were waiting for the insulation to start and the smell (so says my husband) started immediately afterward and that was the only thing done on Monday. They did test the air for isocyanates after spraying on Monday and said there were none detected afterward. We've asked for the report confirming that in writing but aren't sure what else we can do.

September 18, 2016 - 10:11 am

We are in the process of building a new single story home in northern Arizona.  Our contractor recommends spray foam insulation throughout the structure.  Please provide your thoughts on the use of this product in relation to health and safety concerns.  I am just now consulting internet information and realizing there may be health reasons for not using it.   

September 18, 2016 - 10:27 am

Thanks for your question. Spray foam has unique performance attributes that make it really attractive. It also has some really gross stuff in it.

The vast majority of spray foam installations go just fine. As far as we know, when it's installed correctly, the material really is pretty much inert after it cures. The issue with this product type is that "going just fine" depends entirely on the vigilance and knowledge of the installer. There's no hard-and-fast rule about whether to use it or not, but these are the things I would advise you to research, ask, or keep in mind as a homeowner:

  1. Do you really need this product? What are the other options? Are you trying to build an especially airtight home to achieve Passive House or net-zero standards? If not, why are you bothering with an expensive, high-performance material like spray foam?
  2. Who will be installing this product? Talk to them directly if you can to gauge their level of knowledge about the materials they use. Do they know that isocyanates are potent respiratory sensitizers (exposure to them can cause asthma, and also they are asthma triggers if you already have asthma)? Do they actually follow the recommendations of the manufacturer regarding layering, cure times, and personal protective equipment? If they suggest to you that these guidelines are overkill or you get any whiff that they might not follow them, request a new sub because they have no idea what they're talking about.
  3. Ensure that no one in your family enters the jobsite while the spray foam is being installed or is curing. (This is much easier with new construction than with a reno, which is good.) Take this doubly seriously if anyone in the family has asthma.
  4. Find out what the relief plan for your family will be if it turns out the spray foam was installed improperly and you end up with a dud house because of it. I'm sure you've seen the nightmare stories .... These are rare, but you should negotiate who's going to take responsibility if you're one of the few this happens to.

Good luck!

April 25, 2015 - 9:17 am

We are a new home owner with the foam insulation. I have many concerns we were not told about before being put in, we live in Texas lots of humidity but we had our windows open the other night to get fresh air and our builders has now informed us that with the foam insulation you can not open the windows or it will over work the A/C the next day it also holds the humidity in the house and causes the carpet and things to be damp? Why am I putting special windows so I can enjoy the fresh air if this can not be done? I was also told when lighting my fire place I will need to crack a window so the smoke goes up the attic. Could anyone tell me who I can call to have this foam tested. Also how do I find out what the company used in the foam. We were not at our house when this was done so we have in idea if there wore special gear or not. I am very concerned and would like to know more about this. What I can do and can not do. I was also told that if something fell on your rood (tree lim) u would not now if you had damage till the would started to mold and do even more damage.
What have we done. You should be able to trust the builder on who they hire.

Thank You

April 27, 2015 - 2:04 pm

Karla, thanks for your questions. I spoke to our building science expert here, and he had the following thoughts:

1. About opening your windows: regardless of what type of insulation you use, if you have a well-insulated home, you will indeed be working your air conditioner harder if you open windows on days when it's humid outside and then trap that humid air inside. Check out this how-to guide on dehumidification in southern climates: http://www.buildingscience.com/documents/bareports/ba-0214-conditioning-...

2. Very tight homes, regardless of the materials you use to make them airtight, are not generally compatible with burning wood in a fireplace.

3. The known risks from spray foam are for the workers who install it. You were wise to depart the premises during installation. As far as the experts know at this time, provided the spray foam cured properly after installation, occupant exposure to toxic chemicals in the foam is unlikely.

4. Many types of insulation (not just foam) absorb water and can mask the effects of a leak.

June 4, 2012 - 10:37 am

"Vacuum insulation panels (VIP) were already developed some time ago for use in appliances 

such as refrigerators and deep-freezers. Their insulation performance is a factor of five to 

eight times better than that of conventional insulation. Used in buildings they enable thin, 

highly insulating constructions to be realized for walls, roofs and floors"

January 31, 2012 - 9:10 pm

I built house in 2009. In january of 2010 - this tangy smell started to come into my basement .
It took two months to go away - i thought it glue - so i grinded floor - Then company that grinded floor - got silica over entire house - that took couple months to deal with. Then in Summer smell started again - hasnt gone away - so i had VOC test done last week - and the test found that the agent used to apply the foam is still off gassing - so if you can help please email jpaulsd@yahoo.com.

January 6, 2012 - 4:15 am

Isocyanates are a highly toxic sensitizing chemical, responsible for documented worker deaths in the automotive industry. Spray polyurethane foam insulation, of any kind, uses isocyanates in 50% of the formulation -- even those claimed to be made with soy or other natural oils. This is not just a DIYers issue. The real issue is the improper formulation and installation of large amounts of spray foam in homes and buildings by poorly trained, unknowledgeable, or even unreputable commercial installers. Get the mixture wrong, the temperature wrong, spray too thick of a layer all at once, use a spray nozzle that hasn't been properly cleaned and maintained and you may get a bad installation and a house full of off-gassing toxic foam that will never properly cure. I personally know of at least six homeowners around the country who have had exactly this happen and they have had to evacuate their homes and find alternative living accommodations. Some of them are afraid they may never be able to occupy their home again because of the respiratory problems the isocyanates have caused now that they are sensitized. When one becomes sensitized, it essentially means there is no safe level of isocyanates your body will tolerate. When so many good alternative insulation materials are available that are truly green and have no health impacts, why take the chance of losing your home and your health by using polyurethane spray foam insulation?!

May 16, 2011 - 5:15 pm

Very nice article although I would like to have seen the "Let's hope that the general public doesn't jump to conclusions too rapidly" comment early on in the article and not at the end where many readers likely have moved on and made exactly that conclusion. Also, if the issue seems to be with DIY'ers and early occupancy, that should have been highlighter earlier on as well. Thanks again for a very informative article.

May 26, 2011 - 2:27 pm

See the guy in the Tyvek suit spraying this stuff? Proper PPE will include a respirator and safety glasses as well, which would be burdensome and uncomfortable as shown spraying foam on a wall, but in an attic spraying rafters? or in a crawlspace? Its true that off-gassing to future occupants is an important criteria on which to grade building materials, but shouldn't the safety and comfort of the installers be at least part of the equation when consumers make these choices?

They say it you can't pronounce it you shouldn't be eating it. Maybe if even the EPA can't qualify how dangerous a product is, you shouldn't be financing the career of a person who will be breathing it because you spec'd it.

May 19, 2011 - 11:42 am

Is Icynene's foam the one that is being applied to the underside of the roof decking? I have noticed some builders are applying some type of foam to the underside of the roof decking.

May 19, 2011 - 1:47 pm

We recently built a new home (just LEED certified at the gold level), and the choice of insulation was one of the most difficult decisions I had to make. Our builders encouraged closed-cell spray foam, as it is the best R factor per inch of insulation. We live in Minneapolis, so we really care about that. The American Lung Association also recommends it, for a different reason: it is the best for mold prevention. After reviewing the MSDS sheets on the closed cell spray foam, I had a really hard time choosing something so toxic to workers and the environment. But in the end, none of the alternatives were compelling enough for us, so we went with spray foam. (Our installer was fully protected, just like in the picture.) I look forward to the day when the products we humans make for our homes are both effective and non-toxic, and our choices are not a trade-off between one or the other.

October 15, 2011 - 7:28 pm

Sprayfoam is EVIL. Make no mistake. First, chemical compounds in anything NEVER stop offgasing. Second, it is not recyclable (Just saying it is carries no credability) I can find no such recycling station. Third, if you need to put on a safety suit to apply it, you are sadly naive to believe it will sit benignly around the structure. Fourth, it is a nonrenewable admixture...need I go on

May 19, 2011 - 1:57 pm

There is a large and growing number of anecdotal complaints about the health impacts of field-applied SFP foam, particularly low density or "open cell" proprietary urethane foams. These are without exception professionally-installed spray urethane foam insulations, not DIY projects. It's one thing to manufacture rigid foam insulations in a controlled factory environment and another thing entirely to manufacture foam insulation in situ in an uncontrolled environment with pressures to get the job done regardless of ambient temperature or relative humidity, and with the house occupants and construction workers as "canaries in the coal mine".

In far too many instances, the home-owners have had to permanently vacate their new or newly-renovated homes because of chemical sensitivity apparently initiated by the insulation. As we know from other chemical sensitizers, such as formaldehyde, initial exposure causes increased and sometimes debilitating reactions to a wide variety of chemical substances.

Aside from the logical absurdity of using petro-chemical foams to save petro-chemical energy (and the earth's climate), there are hygrodynamic reasons for avoiding relatively impermeable building materials such as plastic foam (I teach hygro-thermal engineering and building science).

It's good to hear that the EPA is finally investigating this health impact, but I would not either put much faith in their objectivity or wait for a "final" recommendation. I have long advocated using natural materials (such as borate-treated cellulose or mineral wool) for insulation as well as for other elements of residential construction (real wood or plywood rather than OSB, and felt rather than plastic housewraps, e.g.) and for building breatheable structures rather than hermetically-sealed containers.

It's past time for us "green" builders to stop accepting manufacturers' claims and apply real science and common sense to our material selections and design decisions.