Lots of great comments here. It almost looks as if the device had been deliberately placed in an area to maximize(!?) the potential for interference (multiple appliances designed to produce air movement; likely pressure differential across doorway providing pathway for draft; unit in walking path). And there seems to be reason for concern whether this room should even be used as the testing location.

It appears there's unanimity on this thread that this device placement is clearly far from optimal, but the proper way to answer Wally's question "whether this radon monitor placement location meets ... Protocols" is simply to go through the applicable protocol(s) and compare this placement point-by-point. It either meets the standard or it doesn't. If it doesn't, it should be a straightforward matter to identify the point(s) where this placement fails.

I think that the ANSI-AARST MAH is written quite clearly, but as always, if there is any respect in which such an evaluation against that standard reveals any ambiguity in the language, please bring it to the reviewers' attention: https://standards.aarst.org/public-review/

Looking forward to the experts' commentary here, but in the meantime, a few items for the discussion:

Here is one study from 1990 that describes the relative effectiveness of air cleaning techniques, but bear in mind the constraints imposed by any experimental conditions lest one generalize too easily to real-world conditions: https://www.osti.gov/servlets/purl/6155991

This document https://www.epa.gov/sites/default/files/2018-07/documents/residential_air_cleaners_-_a_technical_summary_3rd_edition.pdf does include the statement "Note that EPA does not recommend air cleaning to reduce the health risks associated with radon and radon progeny." More detail is provided in that document.

The bottom line appears to be that although some air cleaning methodologies may, under certain conditions, reduce either radon itself (via use of adequate adsorbent media) or the PAEC of its airborne progeny (via HEPA filtration), the degree of reduction cannot be relied upon to be tantamount to effective mitigation via more classical means (e.g., SSD).

And even in those cases where PAEC is reduced somewhat as a result of lowering the concentration of airborne particulate matter (via removing those particles carrying radon progeny--the attached fraction), the result is likely to be an increase in the unattached fraction that has been understood for some time to pose a greater health risk: https://aarst.org/proceedings/1991/1991_02_Overview_of_The_Unattached_Fraction_of_Radon_Progeny.pdf

I support folks (both manufacturers and professional installers) bringing whatever quantified evidence they can to Mr. Snead.
While perhaps Mr. Thies's experience may not be dispositive for all scenarios nationwide, it might strike me as very close to it if he could also quantify the volume of installations he's done over the years, with data for installations with such mats compared with data for non-installation situations (the control group) in the same region. Add other practitioners from elsewhere in the country with similar datasets and affidavits, and that should be convincing for most.
This also leads me to ask:
- What level of proof do the Denver code officials say they need from those who are proponents of installing soil gas mat systems?
- What level of proof are they now satisfied with that demonstrates to them that gravel is effective and necessary?
It seems to me that the volume and quality of evidence for soil gas mat systems today might well match what was in place decades ago when the use of gravel originally became recognized as an effective solution.

Henri, if you could cite specific aspects where the current standards appear to be unclear and if you have specific recommendations for how that lack of clarity could be remedied, these are always the kinds of things that the standards committees appreciate learning about and want to address. As I'm sure you know, procedures and forms are available here: https://standards.aarst.org/public-review/

It also occurs to me that:
1) a client's resistance with respect to the need, in clearance testing, to retest units that previously tested low is probably common, and therefore
a) more education to practitioners about these requirements and
b) advance advice to clients about what they can expect regarding post-mitigation clearance testing
may be called for;
and
2) an explanation to the client of the rationale for the clearance testing requirements may also be helpful. I seem to recall that there were those mitigators who have described cases in large buildings of elevated radon levels that arose after the initial round of mitigation. The issues of
a) reasons for the appropriateness of full retesting,
b) rough likelihoods of what clients can expect, and
c) how further clearance testing is to be carried out if one or more units are found to be elevated after the first or subsequent round of mitigation
are all things that both professionals and their clients should have clarity about.

Thanks very much for the reviews!

To Chrys's question, we had made a decision to put the Resources tab up only in Module 3--which made reference to some items we posted there--but your comment does raise the question for us about whether we should simply show that tab no matter where one is in the course.

I'll admit that it is rather understated, but at the top right of the display screen when one is in Module 3 there is the "RESOURCES" tab with a few standard EPA items available via links in a drop-down menu. See the image attached that shows how that appears.

If there are any places where we direct people to the Resources section, but don't have it posted, please let me know at KevindotStewartatLungdotorg exactly which Module/page that's on. Thanks for bringing this up. And of course, for everyone, don't hesitate to use freely the opportunity for remarks in the Evaluation at the end of the course.

Very generous! You have certainly become one of those folks your Dad advised you to go to conferences to listen to. :-)

You ask a good question, Daryl. A few thoughts:
- This would be difficult to research, in part because we are only now learning some things about the disease process of COVID-19, and not least because the long latency period for lung cancer means that we would probably not have a clear idea of any actual change in risk for many years. But this is certainly something to keep paying attention to down the road.
- I would prefer to see proposed some physiological/radiological mechanisms by which COVID-19 might promote oncogenesis due to radon and its decay products, but for that I would need to defer to scientists and physicians who are familiar with everything needed to credibly make such hypotheses.

I remember Bill Brodhead had a situation in his high homes where a tiny doorway entry pad (only a couple? of square yards in area) needed to be addressed as the stubborn source. Hadn't seen that ruled out yet. And I like Henri Boyea's checklist. Really hoping that you can get some fast-responding grab results to give more "texture" to the airspace you're working with--for example, are there any gradients at all that might at least point you to the right wall to focus on?

This is good news, Chrys.
Every new step like this can allow us in the rest of the country to point and say, "Well, someone else is already doing that successfully, so anyone else with a similar idea wouldn't be stepping out into the void." :smile:
Curious about a few things:
- What are "short term dwelling rentals"? I.e., when is a dwelling rental not short-term? When is a short-term rental not a dwelling rental? Are hotels and motels included in any way?
- How do "short term dwelling rentals" differ from "vacation rentals?"
- What fraction of unincorporated Boulder County's rental property for human habitation is included in the two categories covered by the ordinance?
- Wondering what motivated BCPH to move forward with this effort? Wondering why the choice was made to limit this ordinance to the rental classes named? And wondering if there are thoughts in Boulder County about expanding it once this "pilot test ordinance" has a track record?

Reflecting my ignorance here:

Wondering if Randy's solution of "Draintile technique # 3" in the document to which he refers readers ( https://fixradon.com/wp-content/uploads/2016/08/RadonMitigationDraintile2014.pdf ) is (or might become) the (or among the) water control technique, recognized as consistent with possible future radon mitigation techniques, recommended (or even code-specified) for installation in new construction where it might reasonably be anticipated that water incursion has a fair potential to be a problem? (I live in such a house where I wish the builders had done more to so anticipate. :sad: )

My points in asking this are the following:
- By encouraging home-builders to preemptively follow technique #3 from the outset, such a thing could, in time, make mitigators' work, where it proves to be needed, so much less troublesome to carry out.
- Emphasis on this technique for water incursion control from the outset could also perhaps help establish it as an SOP for the water-control industry to follow should they be called to retrofit houses not so equipped.
- I know John could write a book, but maybe if there could be more steps made to get out in front of this issue in a cooperative way among the builders, the mitigators, and the water-proofers, maybe there wouldn't be the need for second volume 25 years from now. Is there any advantage in holding, say, a joint webinar to help those stakeholders hear one another and address this one issue? Let me know.

Nice thread. A good example of the high quality of the advice this listserv can give ... and the amazing stuff one might never have known!

This thread is a good time, I think, to call attention to the fact that the process by which ANSI-AARST standards are developed include, in addition to ensuring diverse stakeholder representation, a required stage of sharing draft standards with the public and the affected constituencies for their review and critique seeking their comments and recommendations for changes.

It has been my experience, having served on certain standards committees, that these calls for review and comment have always been made openly (through forums such as this listserv), and that all comments offered through the straightforward mechanism provided are given a full hearing and consideration by the relevant committee. This process is painstaking and may take some time to come to resolution, but it has the advantage of ensuring that opinions are widely sought, and that all voices are given fair consideration without fear or favor.

Finally, please note that, even once all comments with respect to a particular version of a proposed or existing standard are addressed, ANSI-AARST standards are not set in stone but are subject to continuing review. Everyone should know that the opportunity for making comments or requesting changes are always available through https://standards.aarst.org/public-review/

Thanks so much for posting! Congratulations to Dr. Burkhart on such a richly deserved honor! It's also great to learn from the write-up how multi-dimensional he is. Within the "radon bubble," one can be misled into thinking that radon is all we do. Bravo, Jim!

Thank you very much for sharing this work.
A few notes:
1) It was reassuring to see the confirmation of reasonable accuracy of the different new consumer radon units under the different test conditions, with no grade worse than C.
2) It was gratifying to see the authors' understanding of the factors involved. Their proposal for recognizing the inherent uncertainties is important for manufacturers to take into consideration in their communications with device users. Many device users do not understand the nature of radon variability or the randomness of radioactive decay, so educating them is worthwhile.
3) This note by the authors in the conclusions also reflects a critical need: "In this project the tests were conducted on newly purchased monitors, and it is possible that accuracy and precision may change over the lifetime of the monitor. Since there exists no framework currently for calibration of these consumer-grade radon monitors, it will be important to determine how they perform over time. It is the intent of the authors to continue this project by keeping the monitors that were evaluated this year so that they may be re-evaluated next year, along with a selection of new monitors." I was gratified to see this need anticipated so well.

Thanks for the additional perspectives and to Mark for explaining his concerns. While I leave it to the author of the blog post to describe the circumstances under which the information was gathered, I must also recognize the appropriateness of some review of radon management being conducted in military housing.

I haven't looked at the details of the OIG report, but it would not surprise me to learn that only the GO-GC housing (i.e., not privately owned, privately managed) would be subject to their review processes, in which case 41% of such housing is much more likely to represent a fair sample of that subset, if that is indeed all that is within OIG's purview.

Mark emphasizes some points that are worthwhile to help put this study into context, and would be worthwhile amendments to the blog post to demonstrate the much larger need that exist beyond GO-GC military housing, but the fact that an investigation and analysis has been done on some small subset of the universe of military housing does not detract from its value as far as that investigation goes, and as long as readers are not led to draw conclusions beyond the scope of the study.

As for the title, it is not uncommon to give blog posts such brief headings, not intending to communicate what might be done by a more academic approach, such as "A Review of Radon Management Practices in a Sampling of United States Government-Owned and Government-Controlled Military Housing." Given that the post was not entitled "Radon in All U.S. Military Housing" and based on the contents of the article, I don't read the brief title used as an attempt to mislead readers. The context and limitations of the analysis soon become plain to the reader.

I would be interested, too, in hearing what Mark Perry identifies as issues with the report, and what Lucy Lim might suggest may potentially be worse environmental health risks than radon in GO-GC military housing. For instance, could occupants there perhaps be subject to certain exposures to toxins not common in civilian housing?

In any case, however, the problem of radon as a major environmental health hazard (if not necessarily always "the worst" in every situation) should be given its due, at least where building structure and operation interact unfavorably with significant source strength and sub-foundation permeability.

There are many areas in the United States and in buildings around the world where radon remains a significant health risk, and the OIG's review does call attention to the great variability in how well the radon hazard is managed, and provides a service worthy of proper attention.

Agreeing with following the science, of course. Would that we had more of it.

* Since not all houses are the same, I'm most interested in what the science says about
- houses with subslab soil gas concentrations / volume production rates in the higher orders of magnitude. This raises the question of whether an installer (climate-permitting) may need to make use of some thresholds for decision-making--i.e., certain values above which they really ought to do exterior fan / above roof discharge. (I make no prejudgment here; I'm only asking a question, and would someday like to know what the science tells us.)
- certain geometries where ground-level exhaust points may create greater propensity for local build-up outdoors or opportunities for re-entrainment. (Certain row-house arrangements come to mind.)

* It's important to pay attention to the "sociological and political science" in the States vs. Canada: When "somebody who doesn't have [good practitioner's] skill set and knowledge gets in the industry" and uses poor piping, poor techniques, for interior fan and/or sidewall discharge and causes problems, how will that perception affect the perception of the industry as a whole for the public and lawmakers? How will not wanting to risk ending up with such a problem affect the public's perception of even the basic value of testing for radon and mitigating it? (Again, I don't prejudge the answer. This is not a rhetorical question. I'd honestly like to know what any scientific approach to the sociology and psychology of risk perception might have to say here.)

Hello, George
In addition to what Larainne and others have written, I want to emphasize some things in response to a premise at your original inquiry

Macon, NC where according to the EPA the radon levels are between 2.0-3.9%pCi — George

1) The units of concentration of radioactive material per volume, picoCuries per liter (here, of radon in air) are admittedly an unfamiliar thing to most. Although the abbreviation "pCi/L" does bear a little similarity to "pct." or "percent", it actually has nothing to do with percentages. Unfortunately, this can be a source of confusion. The numbers on the EPA Zone maps are not percentages.
2) Another important thing to understand is that the EPA Zone Map does not say that radon levels are within certain ranges, only that--based on the preliminary information available at the time the maps were constructed (nearly three decades ago)--the predicted countywide average screening level in the lowest livable area of the building was expected to be in the given range. Therefore, it must be recognized that radon levels in specific buildings in Macon, NC may be less than 2.0 pCi/L or they may be greater, even in some cases much greater, than 4.0 pCi/L.
3) As Larainne said, the radon maps have emphasized, from the start, that they were not to be used to decide whether to test. Their purpose was only to help decision-makers allocate limited resources in a manner likelier to have more benefit.
4) Also, from the start, EPA clearly recognized the preliminary nature of the maps and encouraged the development of better information over time.

Curious what changed between "RP265 running at 0.5" static pressure" and "GX5 which is nearly maxed out at 4.7" static." You sealed off the short-circuiting of air flow present in the original configuration?
Also curious how you reached below the "14 to 22 inches of concrete" to nonchalantly "excavat[e] a couple 5 gallon buckets of soil"