Same issue in Northern Nevada. Radon gas seeps in.

Indeed - radon checks are a standard part of pre-purchase home inspections, because remediation can be quite expensive

We had such a remediation done recently, in Alberta close to the rocky mountains.

Costs were around $2,000 CAD to install a sub-slab depressurization system (i.e. a fan that pulls air from below the house and vents it away from the house).

Radon values dropped from around 500 Bq/m3 to less than 20 Bq/m3.

Those systems must be new. The classic solution is to install drain pipes before pouring the slab, so one can imagine how difficult it would be using 1980's construction techniques to retroactively add piping below a finished house.

We also had to dig trenches to lay natural gas lines, but we have a way to do those with horizontal boring techniques (of course then people who didn't know what they were doing put them straight through sewer lines, causing backups, visits from the Roto Rooter man, and subsequent explosions due to dumping natural gas straight into the sewer main).

Is it safe to assume they're using something like that with perforated pipes to exhaust radon?

>Those systems must be new. The classic solution is to install drain pipes before pouring the slab, so one can imagine how difficult it would be using 1980's construction techniques to retroactively add piping below a finished house.

They didn't had diggers and drills in the 80's ?

It's easy to make a hole. Making a hole underground without making a hole aboveground is harder.

For instance, the first subway systems in London were installed via cut and cover. Dig a trench, build a roof. Usually those trenches were in the street, or a former canal, not under a building.

Using modern tunnel boring equipment, Seattle's attempt to move the downtown section of 99 into a tunnel ended up stalled for a year because the ground shifted and pinched the boring machine in place. Oopsie.

And of course if you're worried about gasses, puncturing a solid piece of concrete is just going to make that problem worse.

I had a side-job installing active, subslab depressurization systems in the 90s, and they were quite well established at the time. The EPA has quite clear and cogent guidance on radon, paraphrased as follows:

Before going with active depressurization, start by installing a sealed sump cover, caulking the basement wall-to-floor joint, and caulking all the cracks in the basement walls, in that order. If that doesn't get the number down where you want it, drill the subslab access hole and install the ventilation piping to the outdoors, but don't install the fan in the middle. Only of those fail to get adequate results, install the fan.

It's really simple and quite cheap. I don't think we ever did a job that was over $1000. Costs of running the fans were pennies a month, and Fantech still sells the classic FR-100 fan all these years later, though there are even quieter options now.

So make the interior of the house the path of most resistance, and see if it will passively vent itself, and if not bore a horizontal tunnel halfway under the house and install a fan to do the job?

No! There is no horizontal boring, at least not on any system I ever touched or heard of. I don't know where that idea came from.

There's typically enough gravel under the slab and around the foundation that there's plenty of soil-gas transport without doing anything more. So the install is just a simple vertical hole through the corner of the slab somewhere. Maybe you scoop out a few handfuls of soil before sticking the pipe in the hole, but there's no horizontal boring. Here's a very typical one:

https://www.flickr.com/photos/34878756@N04/9350845974

Here's another, including a side tap to a crawlspace:

https://science.gc.ca/site/science/en/blogs/science-health/e...

Not shown is the crawlspace portion of that system, which would use a horizontal perforated pipe _laying on the surface of the crawlspace floor_ and covered with a plastic membrane that's taped to the walls:

https://www.nachi.org/gallery/radon/crawlspace-radon-system-...

At no time is pipe tunneled horizontally under the house.

Most of the cost is the installation of equipment in the existing home. In areas of the country that have a lot of radon, it's not uncommon to install the equipment during construction of the house foundation, which then only adds a few hundred dollars to the total cost.

> Radon-resistant new construction (RRNC) typically costs a builder between $250 and $750. RRNC could cost less than $250 if the builder already uses some of the same techniques for moisture control.

https://www.epa.gov/radon/radon-resistant-new-construction-h...

Not uncommon as in it's building code in those areas.

Tricky bit I think is when you live in a state with small pockets of radon instead of broad regions. Then you're back into crapshoot territory.

Happens almost everywhere where basements exist.

Higher amounts of granite in the soil make it worse. Depending on the area, it can be a severe health hazard to the point no one puts in basements - others, kinda meh.

Here is a map! [https://www.epa.gov/sites/default/files/2018-12/documents/ra...]

I would think you want basements (and ventilate them), since otherwise the radon comes directly into the living space.

It can be an issue everywhere, Radon is the second leading cause of lung cancer, after smoking.

I'm in the middle of moving from Texas to New England. In Texas, Radon is such a "not a problem", that I've never considered it before our move. In New England, our basement tested above the "safe" limit (iirc, 4 somethings), so we are having a venterlator installed for ~$1.4k.

In the south, Radon "can" be an issue, but it simply isn't an issue. In New England, it is often an issue.

Nobody in Texas has basements.

Heavy metals in the nearby earth are the obvious parameter here--you need something to decay into radon for there to be radon.

But I think another factor has to do with the water table. In some places the water table rises high enough to flood basements, so you don't usually have basements at all in those places, and subsequently you don't have large reservoirs of radon adjacent to living spaces. I know of some people here in CO (where we have decaying granite in the soil) that don't have a basement and still need a radon ventilator, but it's not very common.

My understanding on why this is, is because in New England there's a lot more granite in the ground. Granite is particularly annoying in that respect because the trace amounts of, i think, uranium and radium that the rock concentrated when it was formed will give off the radon gas when they decay.

and that can mean high outdoor radon levels... a home inspector back in early 2000 told me about a seller sneaking back in and opening basement windows to attempt to pass a radon test (sensors left in the basement over the weekend.) The inspector caught it but let the test run to completion - at which point it failed anyway because the adjacent "forest with exposed granite rocks" was a fine natural radon source...

> In the south, Radon "can" be an issue, but it simply isn't an issue.

There's more to the south than Texas, y'know. I can't recall if radon tests are required during a home inspection here in NC, or just highly recommended, but when I was buying a house last year I toured several homes that had radon mitigation systems installed.

See my other post in this thread, active ventilation is the last resort if passive methods don't get results. Perhaps in the middle of a real-estate transaction it's easier to just pull the trigger on the sure-fire method and get it over and done with...

...but if you ever get annoyed by the whir of the fan, unplug it for a month and do an alpha-track monitor. (Or get a continuous monitor, they're cheap now!) There's every chance that simply having the cracks caulked and the piping in place, might do the trick all on its own, with no need for active depressurization.

This claim (which ultimately came from the EPA) is suspect at best. It just comes from assuming a Linear No-Threshold model, which flatly contradicts the available body of medical evidence.

https://youtu.be/TYZglUjLE0Y

Thanks for posting this, I will check it out. As a Midwesterner with a basement I had once looked into those claims about radon as the second-highest cause of lung cancer with concern and found the evidence much weaker than I expected. Even by EPA estimates[0] almost 90% of the lung cancer deaths attributed to radon are smokers (i.e. who have already weakened lungs), and there didn't seem to be good evidence of damage from basement radon for non-smokers.

[0]https://www.epa.gov/radon/health-risk-radon

Let me preemptively disclaim that I do have nitpicks about the talk I linked, but IMO his main argument is sound.

In particular I think his scientific explanations aren't always fully accurate, and he worries about measurement minutia very strenuously. Also at one point he says you could breathe 80% radon/20% oxygen, which while chemically this is true, radiologically it would be suicidal.

Those nitpicks aside, his point about the EPA LNT model having no clothes is spot on. After "the scales fell from my eyes," now I can't not notice how all those same Party Line Claims get parroted in every piece of radon-related content.

Another glimpse down the rabbit hole is this interview with the late Dr Bernie Cohen, who studied the link between residential radon and cancer:

https://youtu.be/xhkBLhw-8pk

The alternative to LNT is to conservatively assume radiation has the maximum effect not ruled out by evidence (after all, radiation is not a criminal defendant that's innocent until proven guilty). This would make low level radiation more dangerous than predicted by LNT, not less.

>The alternative to LNT is to conservatively assume radiation has the maximum effect not ruled out by evidence

No, the alternative is to look at the actual data (including the actual dose-response curves), rather than fabricating fraudulent data to fit the LNT model (externally imposing a wrongly-shaped dose-response curve by fiat).

Here's one of the more relevant timestamps from the talk, a section which then runs on into Part 3.[0]

However to know what's going on, you really should just watch the whole thing prior to formulating your next counterpoint. Otherwise this immediately devolves into a very long and boring comment thread, where I laboriously digest the points from the video and feed them to you through an HN comment-sized straw. ;)

[0] https://youtu.be/37pCurE0nxo?t=1671

The LNT is consistent with the real world data, cherrypicked bullshit from pseudoscientists notwithstanding.

This is why the NRC recently rejected a call to stop using LNT in setting regulations. Their responses to the details of the petitions are pretty damning.

https://www.regulations.gov/document/NRC-2015-0057-0671

Now, at the very low doses typical of large scale exposure from nuclear accidents, it's true that the evidence does not directly require LNT. That's because the effect predicted by LNT is so small at those doses that it's swamped by noise and unmodelled biases. No practically obtainable data could do the trick.

But note what this means: the data at those low doses is so poor that it's consistent with an effect greater than from LNT. It cannot rule this out.

I'll add that a favorite pseudoscientific claim from the radiation apologists, radiation hormesis, would imply a larger effect from radiation at low doses than predicted by LNT. That's because hormesis putatively acts by inducing repair mechanisms above some dose, bending the curve downward. Below that putative threshold, the curve has a high slope (and thus more damage per increment of dose) than the linear curve of the LNT.

My mistake. You're right.

Go back and read about the malfeasance of the petitioners there. They do things like cite a study, neglecting later data from the same study where the effect they want no longer shows up in the better data.

Policy has to go beyond what is rigorously demonstrated. It's not like criminal law. Technologies are not innocent until proven guilty. Just because LNT cannot be demonstrated at the doses relevant to nuclear accidents doesn't mean regulators should assume no effect.

Claims of malfeasance go in both directions.

>Policy has to go beyond what is rigorously demonstrated.

Thanks. I can see we're done here.

Yes, indeed. We are done. You are living in a fantasyland, not in the real world of how regulation and politics actually work.

But at least you can admit LNT is consistent with the evidence? The claim to the contrary is an outright lie.

Sure why not? If it makes your day get any brighter: you're always right and good, and I'm always wrong and bad. :)

Cheers.

Indeed, it's good to be cautious of such claims. Low level radiation could be worse than predicted by the LNT.

It feels like this is something that should be easily amenable to statistical analysis.

Large numbers of people get diagnosed with lung cancer; smoking rates vary widely and smoking is typically recorded in patient histories; typical radon levels vary widely with geography and are recorded / known. This looks like a near perfect natural experiment, no?

That research was done. The results weren't what regulators expected, so you never got to hear about them.

https://youtu.be/xhkBLhw-8pk

Some places in Czechia have a huge problem with radon emanating from the ancient bedrock below. These places, even though rural and not polluted, tend to have more deaths from lung cancer than the rust belt in northern Moravia, where air quality in general is worse, but the radon problem is almost non-existent.

Newly built houses are required to be radon-proofed, AFAIK.

I remember that "radon killer" story being vastly overblown / debunked. Apparently anything up to 150Bq/m3 is fine or even beneficial for your health. [0]

Has the debunking itself been debunked? It's hard to keep track.

[0] https://www.osel.cz/3436-radon-neskodi-a-mozna-i-prospiva.ht...

Because the rock formations in some areas are more prone to production of Radon gas which slowly diffuses through the soil. Basements in those areas tend to have Radon infiltration. It is obviously very slow but the basement is a low point and often not well ventilated which can allow the Radon to accumulate.

Poured slabs are less permeable, not a low point, and tend to have better ventilation either intentionally or unintentionally.

It is a myth that radon collects in "low points", concentrations are low and it diffuses as the molecules bounce around. However, as you said radon is entering into those areas primarily, which means it will naturally be higher in those areas. Secondly basements often have poor ventilation, which is not to say that the radon cannot otherwise escape, but ventilation can disperse it much more rapidly than diffusion.