In researching the subject of Radon mitigation, I came across this article, Titled "Radon - A brief discussion", by Caoimhín P. Connell (Forensic Industrial Hygienist)

Please read that whole article before posting any comments. It's a long read, but I'd like to ensure everyone who comments on this topic has in fact read and understands the article. No biases please! :)

The first paragraph states the following:


A large portion of the general population is under the misconception that the frequently published risks associated with radon are well accepted scientific facts. In reality, the vast majority of well designed studies do not support policy or positions that exposures to indoor radon pose a significant threat to health, and indeed, the majority of those studies indicate that, at concentrations typically seen in homes, as the level of radon increases, the risk of lung cancer goes down, not up.


After reading the science behind Caoimhín's well-written and thorough article, I have to say I agree with his words and message. So what does that mean to an energy auditor? What advice am I to give to a homeowner whose home is under constant depressurization causing backdrafting with their woodstove or failing to pass worst case combustion safety tests, all because of their radon fan in the (nearly-conditioned) crawlspace? I realize as a BPI graduate I am supposed to consider Radon. But what do I tell folks whose Radon mitigation system indicates levels far below 7 picocuries? Should they run that fan that consumes 526 kWh/year, costing them $70/year?

I welcome your input. Love this community!


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LIKE! Ahah! You found it, tedkidd. I have been trying to "follow the money" to determine when and where the influence was for the EPA's standards on Radon. The tobacco industry, of course! The mystery is solved. Thanks for that! ;) 

Ted, you did it again!

I would say that there's nothing like explaining the facts, but that would only count for the people who are interested in them!!!

;) I love uncovering absuedities...

Funny how creatively and vehemently people will argue against facts when their poorly constructed schemas, or their livelihoods, are threatened.

Tell them the truth as you know it, and back it up with the facts!!

I encountered the article a while back while studying radon.  It is interesting to see a discussion of it here as I wasn't sure if it had an validity or not.

My 1880's house tested at 16pC/L.  I was unable to install a sub-membrane system due to the limited access in the crawlspace.  With sealed combustion appliances in the crawlspace, two small 100 CFM crawlspace fans enabled me to depressurize the crawlspace slightly.  I also sealed the floor penetrations as much as possible between the crawl and the house.  This type of system is a sub-floor depressurization system and could cause backdrafting if atmospherically drafted appliances share the space.

I also sealed my return ducts and installed an HRV.  

Apart from reducing "radon" (quotes intentional due to discussion) to "1.4", there were numerous other benefits I haven't heard much talk about.

Benefit #1)  During my travels in the crawl, I encountered a lot of wooden debris, moisture, and, big surprise, fungal growth.  Drawing air out the crawlspace ensures that contaminants are less likely to find their way into my living space.  Other contaminants include mouse shit, 100 year old coal dust, and more!

#2)  Here in Colorado, during spring melt-off, the crawlspace gets very damp.  The fans help reduce moisture in the crawlspace, good for durability.

#3)  Apparently there are other gases, like methane, that can enter the home.  My system removes these.

#4) In the case of a sub-membrane (plastic vapor barrier) system, I recommend these anyway to stop moisture from entering the home.  The radon mitigation contractors I know do the best job of installing a sealed vapor barrier.  

#5) The fans, HRV, and sealed return duct have made the indoor air quality noticeably better. This wouldn't have happened if I hadn't tested for radon.

Finally, a lot of the discussion so far has focused on the invalidity of testing.  As I made improvements to my home, I tested at each stage:  Installed first fan, levels dropped from 16 to 10.  Second fan down to 6.  With the HRV and duct sealing, levels finally reached 1.4.  These interventions certainly seemed to be reducing radioactivity in the home (through a replicable testing procedure, mind you!).

I find nothing incompatible with improving indoor air quality, reducing radon, and building performance.  This discussion wouldn't have given me any reason to do anything differently at my place.  Reducing risk (however small, nuanced discussion about risk perception aside), improving indoor air quality, improving durability, etc, are all good things in my book.  

Would be nice to have a "what kind of junk is  floating around in my crawlspace?" testing procedure, right? A little contraption you put down there that samples the air over time for all types of contaminants and sends it wirelessly to your smartphone. Who is going to invent that?

Perhaps in this case instead of detecting a gas a radiation counter, one that distinguishes types, some of these can be hooked up to IoT.

Also adding that the trouble with hot-particles in general isn't just breathing them, if they get into anything as food they can be lodged in the gut as well as breathed in.

The concentration of the radiation doesn't mean much compared to swallowing, breathing or having the skin absorb something that lodged next to a cell.

Once that happens getting a cancer is about 100% certain over time, "Diffusion is not the solution to radiation.", you have to get rid of the source, if there is a source it's an odds & circumstances situation.

very cool! energy impacts?

A popular, however poorly thought out, concept is “Well… one can never be too careful.”

In fact, one CAN be too careful, and as one attempts to mitigate vanishingly small risks, the cost associated with the practice rise exponentially. 


Thus, in a recent post, the idea that one has “improved indoor air quality” by making insignificant changes, buys into the idea that by making an insignificant change, one has achieved anything at all.  In reality, one has merely expended financial resources without benefit.  Or, as in the referenced case, one has expended financial resources and possibly disimproved indoor air quality, under the false concept that one has improved indoor air quality (IAQ).


Let’s take the first notion: Reducing radon in a residence has improved IAQ.  We will begin by making the argument easier by assuming that all monitoring and measuring discussed in the post is accurate and valid.   In this case, the unsupported argument is made that because one has reduced the radon, one has improved the IAQ.  However, depending on the model used, one has actually achieved one of two things: 1) Nothing at all (if one uses the generally unaccepted EPA linear no-threshold dose-response risk model); or 2) By reducing the radon concentration, one has increased the risk of cancer for the occupants (when using more realistic dose-risk curves that are supportable by science).  Therefore, by reducing the radon from 16 pCi/l to something less, the occupant cannot demonstrate that, based on radon, the IAQ has actually been improved.


Next, let’s look at methane.  Methane is a completely non-toxic, odorless, invisible gas.  One could breathe enormous amounts of methane and, as long as the O2 concentration is not affected, the individual would be completely oblivious to the fact.  The argument that one may have reduced the methane in one’s indoor air.  OK…. That would be rather like saying, “Today, I reduced the number of blue chairs I have seen by putting on special $200 glasses that block out all light for five minutes, therefore, my risk of contracting gall bladder disease caused by seeing blue chairs has been reduced.” 


Considering for a moment that seeing blue chairs does not increase the risk of gall bladder disease by even the slightest amount, how would one thus justify the expenditure of the $200 on special glasses meant for this purpose? 


I have been performing IAQ investigations for over 27 years, and I have never encountered a methane problem in a normal residence.  I have certainly encountered methane problems in residential structures that were built over landfills that were not properly designed.  In those cases, large civil engineering projects that cost millions of dollars were needed to vent-off the excessive methane.  The concern here was not IAQ issues, the concern was that there would be a massive explosion that would destroy entire neighborhoods. 


Therefore, if one argues that they managed to improve their IAQ by reducing the concentration of a non-toxic, colorless, odorless, gas from one insignificant concentration to another, equally insignificant concentration, then I would have to accept the decision criteria for the conclusion is irrational and not demonstrable and certainly not based on any evidence.


Next – Finding fungus in a crawlspace – any crawlspace – is not a surprise, it is the norm.  Every crawlspace in Colorado, has fungus.  Every crawlspace in every state of the Union and Canada, and Mexico has fungus.  It would be impossible to find a crawlspace that does not have fungus.  I have been involved in many fraudulent scams where a “Certified Mold Inspector” or other poorly trained “certified” consultant performs “testing” in a crawlspace, or produces photographs of fungal growth in a crawlspace, and then frightens the property owner or management team with utter nonsense about the need to remove the fungus.  Often, such schemes involve tens of thousands of dollars of useless “remediation” efforts, and very often (if not virtually  always) the work actually results in increased fungal exposures!


Next – vapor barriers, and fans.  Some time ago, a municipality was considering requiring vapor barriers and evacutory fans in crawlspaces to reduce moisture – The intuitive idea was that these practices would reduce moisture and therefore, reduce the occurrence of “toxic mold” in the crawlspaces.  Ignoring for a moment that there is no such thing as “toxic mold,”  the municipality approached a Section of the American Industrial Hygiene Association and asked the membership what we thought of the idea. 


The AIHA membership said it was a bad idea and if implemented, the practice could just as easily increase the moisture content of homes and as a result, result in higher levels of mould growth in crawlspaces. The municipality ignored the advice and implemented the requirements in their building codes.  The net result was not just overall increased moisture in crawlspaces, (rain forests in some crawlspaces) and a greater incident of mould in those areas, but also the increased appearance of wood destroying fungi such as Serpula lacrymans that caused catastrophic structural failure in some structures.  The fix? Well, remove the vapor barriers and fans, of course! 


When setting out to “fix” something and improve something in the field of human exposures, all too often we see the approaches are based not on sound, evidence-based, articulated and demonstrable goals, but rather on “feel-good” popular myths.   Occasionally, those “fixes” not only don’t “fix” anything at all, but rather bring with them an entirely new set of problems.


Just food for thought – I would be happy to address each of the above in detail, and separately, as I’m sure this has raised rather a lot of questions.

Couple thoughts:

-I don't see how a floor vapor barrier with sub-membrane depressurization could increase moisture.  I can tell you that simple depressurization has reduced the humidity levels in the crawl.

-It doesn't matter much to me a fungal growth is toxic or not, or methane is good for me or not, I still don't want to breathe air from my crawlspace, period.

-The financial impact on these improvements was minimal, and hardly worth getting worked up about.

-Without testing IAQ, I accept that it is speculative if it has been improved or not.  However a reduction in measured radioactivity is a positive indication of improvement, and there is no evidence IAQ has been harmed.  

-Finally, while discussion is fine and well, I'm not about to change my protocol based on the opinion of one person and an article on the internet.  I'm basing my recommendations on what the EPA says because frankly, I'm not a scientist and the simplest course of action is to follow what the majority say.  While the author of the above post is well spoken and sounds convincing, the arguments for doing something about radon are still more convincing to me than what I've read in this discussion.  I'm not taking a position here, but I think everyone ought to be wary about accepting this line of reasoning (just as we've been cautioned to accept the status quo).  

You don't need to be a weatherman to know which way the wind blows and you don't need to be a forensic industrial hygienist to know when your crawlspace is drier, cleaner, and smells better. Thanks for bringing some common sense to an increasingly silly debate Cameron. 

Well the point of this posting was to expose to this community the fact that the information "the majority" references for their data is simply not valid in real-world application. The EPA's action levels are based on false science. They admit it, and science proves it. And Caoimhin's article is not the only one in existence that points this out. So why would we--as pseudo-scientists, who have analytical thought capabilities--continue to follow the status quo when we know better? We are the ones who write the policies for the home performance industry, so let's take a really close look at this when doing so. This post's intent was not about how to dry up a crawlspace, it's merely a way of saying "Hey folks, something is wrong with what we've been told by the EPA!" (an all too frequent case, I'm afraid)


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