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Comment by nancyminusone | Hacker News Reader

Every time you look up something related to Radon, it's always cited as "the second leading cause of lung cancer after smoking"

I wonder if that's really true.

Radon is a big deal where I live. Most homes have a radon mitigation system which is a 20-watt fan that goes over your sump pump hole, and runs continuously to a vent on the roof.

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I bought an Airthings radon monitor because of that stat, and one thing that I have learned is that those mitigation systems do not necessarily work. I have a system that works, but initially, even though my house had a system, it did not reliably keep the radon levels below the federal action level.

Barometric pressure, temperature, and HVAC all seem to have some bearing - tightening the house for air leaks actually did a lot of good in keeping levels low. Also, sump pump failures or ground water levels can "push" radon into the house. I dug a deeper sump pit and also put a secondary radon fan to pull air out of my sub-foundation drain pipes to ensure the air below the house is cycled.

Still, in Boulder County, my house will fail its radon test after a 2 hour power outage.

I am an evangelist for continuous radon monitoring, alerts and tests.

I bought one of those because I have a couple radium clocks and a nice sample of uraninite, which is a tiny collection compared to the real enthusiasts but probably more radioactive stuff than the average person has. Radon is in the decay chain.

I've never seen above 0.7pC/L which is pretty good, although I don't know what proportion of the activity that is there is natural, or how much more it would be without the fan. I'm not sure what the natural radon levels even are in my area, I think the radon fan is just part of code here.

My house is a raised foundation and they covered all the ground underneath with plastic and put perforated pipes underneath that pull the air out. Radon went down 10x. The company has a 5 year guarantee.

> tightening the house for air leaks actually did a lot of good in keeping levels low

Wait, really? Intuitively I would expect the opposite, that a draftier house is better for radon levels indoors

There's probably a tipping point between the stack effect (hot air rising and pulling on the radon) and drafts bringing in fresh air diluting the radon.

A better seal maintains the pressure in the house better.

Drafts form either from temperature differential and wind outside pushing in.

Radon coming up from the ground is still heavier than air, so it won't mix in very well if it can't displace anything.

It's not a perfect solution, as air movement from circulation will help it mix in, but a good envelope will help a mitigation system out quite a bit.

If too much air can leak in from too many places your exhaust fan won't be able to keep up and maintain a pressure differential across the whole area and fully cycle through the air volume. Instead of the air mass as a whole flowing towards the exhaust you will instead get mixing of inside and outside air and then pulling of a fraction of that. Ultimately failing to properly cycle the contaminated air and also spending a lot of energy on exhausting what was previously clean exterior air.

With it more sealed so you can get a decent static pressure it is like flushing a clean fluid through a pipe and only really needs a little more than the pipe's volume of fluid to clear it, with it poorly sealed it is more like scooping one cup of water out of a contaminated bucket, then pouring a clean cup of water back in and letting it mix before repeating the process, with the hopeful goal of eventually having an uncontaminated bucket of clean water. It would eventually be clean enough sure, but you might have to go through 1000x the fluid volume to get to a clean enough point.

Technically you could just increase your exhaust fan's power until it creates decent static pressure in even a leaky home, but you would also be exhausting a lot of the energy you put into your climate control system.

I bought a house in the hills of Los Angeles and we tested for radon. Turned out it was very high, and LA is one of the few places in California that has high radon. We got it mitigated, and it wasn't that expensive. I talked to neighbors and real estate agents, and no one wanted to know anything about it. I was shocked. Everyone is pulling the wool over their own eyes here.

It’s knowledge that can only hurt you if you’re selling houses. Just like lead paint - it’s smart to be dumb.

If ignorance gives you cancer while you live there, maintaining it in the hopes of avoiding disclose requirements in the future is both dumb and evil.

And certainly people would not be dumb and evil?

I believe I have a significant body of counterevidence.

Nothing reveals the darkness in people's soul more than real estate.

> We got it mitigated, and it wasn't that expensive

What's the process, usually, adding some special ventilation system to the house?

I’m actually scheduled for an install next Monday. Mine has two components:

1. The ventilation isn’t really “in the house” - the fan pulls from below the slab (and exhausts outside) to prevent radon seeping through. 2. Based on the best guess about my home age/area and radon patterns in my house, the slab was probably poured around the furnace, so the mitigation will include disassembling/reassembling my furnace to seal underneath.

Drill a 6” hole through the concrete foundation and dig out about 15-20 gallons worth of material. Install a 3-4” PVC pipe into the hole (the end of the pipe should be a few inches below the bottom of the foundation) and seal the hole up with hydraulic cement. Continue the PVC pipe up out out of the house. There are lots of rules around distance of the outlet from windows and doors and how high above roof line. Inline install a radon fan. How big a fan you need depends on many factors like soil type, home dimensions, etc. The fan runs 24/7 creating a vacuum under the house.

Yes. I went into detail in another message in this thread. I neglected to mention that our garage is a slab foundation unlike the rest of the house so it involved drilling a hole and putting in a ventilation pipe into it, as others have mentioned.

Do you have a source for the high radon in LA? According to this county source it is pretty low in LA county but much more pronounced in Ventura county (1% homes with high levels vs 14%). I imagine there is some potential for accumulation effects but this is probably much worse in markets where the homes actually have basements.

http://www.publichealth.lacounty.gov/eh/safety/radon.htm

I found a map at some point. It was 5 years ago. I'm in the San Fernando valley area myself. I do believe there were hotspots in the hills here but perhaps it was mostly ventura county. I'd have to find the map.

Much of LA has some of the worst air in the country, so I think it selects for people who don't care about being poisoned by their environment.

> Every time you look up something related to Radon, it's always cited as "the second leading cause of lung cancer after smoking"

> I wonder if that's really true.

That claim is in fact based on extremely poor research methodology. It is made by combining the linear no-threshold model of radiation damage (which contradicts everything we know about cellular repair and hormesis) with evidence from "case-control studies", a kind of retroactive hand-waving that has nothing whatsoever to do with a "controlled trial", despite the name.

I have never heard of radon as a domestic health concern (40+, have owned multiple houses). Does this vary by country or relate to mitigation industries in a locale?

It varies by the amount of uranium underneath you. So yes, by country/state/province/etc.

Australia has the largest uranium reserves, but I've never heard radon mentioned here as a concern, so I assume it just comes down to the reserves being very specifically located.

I guess it's not much of a concern in Australia, I guess.

https://www.arpansa.gov.au/understanding-radiation/radiation...

>In 1990, ARPANSA conducted a nationwide survey of more than 3300 Australian homes to determine the radiation dose to the Australian population from exposure to natural background radiation, including radon. Based on this survey, the average concentration of radon in Australian homes is about 10 Bq m⁻³. This is less than in many other countries and compares to a global average indoor value of 40 Bq m⁻³. Average radon levels in Australian homes are only a little larger than the radon levels in outside air and are of minimal concern to health.

It's a concern for miners, but not normal homes. Also radon often concentrates in basements, and you don't have those.

I heard that even houses next door to each other can have different amounts of radon.

It varies with geology yes, produced by the radioactive decay chains of U-238 and Th-232.

https://www.pnas.org/doi/10.1073/pnas.2408084121

If I recall correctly it can accumulate more readily in basements, so that's another factor. The house I grew up in had an exhaust system installed due to elevated radon levels.

Varies by geography, so yeah, by country as well. It's a major issue in the US as per the comments in this thread, but here in Australia, almost the entire country[0] has indoor radon levels at 5% or less of the concern threshold level[1]. A few people near certain industries may need to be concerned, but it's not the issue it is in the US.

[0] https://www.arpansa.gov.au/understanding-radiation/radiation... [1] https://www.arpansa.gov.au/understanding-radiation/radiation...

An estimated 38% of homes in my county have elevated radon levels.

We tested for radon when we bought our house and found the levels to be very high.

Fortunately the builders had installed a passive mitigation system so all we had to do was install a fan.

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