Radon Mitigation & Filtering Air

15 Feb

This post will expand upon a topic I cover in the book in the chapter about air: The dangers of basement radon and how to deal with it. Radon is a natural product in the decay of underground uranium. In short, certain rocks create this crap, which then decays into other crap, which eventually emits alpha radiation.

Alpha radiation is a lot like a big 45 slug. It doesn’t penetrate deeply, but does quite a bit of damage to whatever it hits. The problem is that when you spend a lot of time in the basement in a high radon area, these alpha particles constantly bombard your lungs. Much of the damage to your lungs is repaired naturally, but every once in a while, your DNA gets messed up and the damage becomes lung cancer.

One of the best explanations of radon I’ve found is here (pdf). It illustrates the points with nice pretty pictures.

What should you know about radon?

1) It’s a regional problem. Inspect a radon map to see if you live in a high radon area. If you do, continue reading. If you live in a low radon area, congratulations. One less thing to worry about!

2) The effects of radon are determined by level of exposure over time and by statistics. Everybody knows one old codger who says he smoked a pack of cigarettes a day for forty years and didn’t get lung cancer: Ergo, smoking doesn’t cause lung cancer! What he misses, of course, is the huge number of smokers who died with their lungs draining out into a plastic bag.

It’s the same with radon. High exposure doesn’t mean you’ll get lung cancer. It only increases the probability you’ll get lung cancer. Low exposure doesn’t mean you won’t get cancer. It only means you have less likelihood of getting it.

3) If you live in a high-radon area, you can get test kits to measure the radon level in your basement. These are available from many sources. I’d suggest you google “Radon” and the name of your state, because many state governments provide low cost (or even free) radon test kits to their residents.

Radon is measured in pico curies per liter of air (pCi/L). We don’t really need to understand what pico curies are to understand the test. Just know that average outdoor levels are about 0.4 pico curies per liter. Consider that a baseline. You can’t do any better than this. Indoor air levels will vary. The experts deem that ten times this exposure or about 4.0 pCi/L or more is a level for concern.

If family members sleep in the basement and you have 16 pCi/L, you probably want to look into reducing radon levels. If you rarely go in your basement and you have a reading of 5.0 pCi/L, it’s not as big a deal.

4) If you decide that radon levels are too high for your family, you can have a radon mitigation system installed or install one yourself. Professionals usually charge between $1,000 and $2,500 to install an active sub slab depressurization system.

What seems like such a high cost to install some PVC pipes with a fan has led some to call radon mitigation a scam or a ruse.
There are many real conspiracies and scams. Radon mitigation isn’t one of them.

If you’re a do-it-yourself type, you can find some good information about installing one of these systems here. Scroll down to “Radon Reduction Techniques for Existing Detached Houses: Technical Guidance (Third Edition) for Active Soil Depressurization Systems” and then click on the text and there is a link to convert it to pdf. This text is about 300 pages and will provide more information than you really need.

The first step to minimizing the level of radon is to paint bare concrete surfaces in the basement and seal any obvious cracks. If you have a sump pit, you might use that as a starting point for designing your own mitigation system.

After sealing the basement as best you can, you could test again to see if you have reduced the level of radon. But I probably wouldn’t. Caulk alone usually doesn’t do the job, because air from the ground has a way of finding its way into your basement!

To understand an active mitigation system, think about the air below your house’s foundation. That air wants to go somewhere and will seep into your house. This is for several reasons. There is often a natural draw of air from lower levels into a house heated during the winter. This is called the Stack Effect.

Heated air rises and leaves the building from the top of the building. Air from lower levels must come in from somewhere. If it seeps in from tiny cracks in the basement, it will carry radon with it.

Sub slab depressurization means that we suck air out from underneath the foundation’s slab and exhaust it, usually above the roof. This carries the radon-laden air away. Just as importantly, it depressurizes the area below the foundation’s slab. So air is less likely to want to flow into the house from below. Think of this as offsetting the stack effect. The air beneath the foundation isn’t being pulled aggressively into the home anymore.

When building one of these systems, one thing to note is how easily air flows under your foundation. If you get lucky, you might not have to install any piping at all. If you have a drain pipe feeding into a sump pit, that might provide all the piping you need. Then, it’s just a matter of sealing the pit and running some PVC piping and a fan to exhaust the air. Call this your X1 system. Test the radon level to see if you need to do something more involved.

Keep in mind that you’ll win in the end. You can test, and if you’re not happy with the level of reduction, you can try something else. A successful system should reduce levels well below 4.0 pico curies per liter. Many achieve readings of under one pico curie per liter.

Filtering Air

As long as we broached the subject of the Stack Effect and sub slab depressurization, it’s only natural that we should say a few words about the daily effects of air pressure in the home and how this relates to some prepping situations.

The air pressure inside a home can be greater than or less than the outside air pressure. With exhaust fans, you can create a relative depressurization inside your home. This can be used to find air leaks increasing your energy bills.

One test is to use a powerful fan attached to the front door to depressurize your house (air blows outside). Then you can measure the level of depressurization you achieve or use smoke candles to seek out pesky air infiltration leaks that cost you money.

If you were to turn the fan around and blow air into your home, your house would be under relative positive pressure to the outside air. In this case, the smoke from the test candle would exit the house through cracks and other openings.

This technique is used for so-called “clean rooms.” If you want to assemble microchips and other sensitive components, to create a clean room, the room can be just slightly over pressurized relative to the outside. This way contaminated air isn’t drawn into the room from small imperfections in the building envelope. The air entering the room can be filtered and you can control it. A HEPA filter will help remove small particles.

A prepper can envision several scenarios. If you’re hit with a dust storm or smoke from a forest fire, a simple HEPA system like this will remove some of the offending material before it enters your home.

This advice of creating a slightly positive pressure inside your shelter is given for dealing with nuclear radiation too. (The link is to a page from a book on Google books titled Nuclear, Chemical, and Biological Terrorism: Emergency Response by Mark E. Byrnes, et. all., Page 108.) The Radiation is carried by small contaminated particles.

I’m not so sure how such a system would work against a chemical or biological terrorist attack, because of our limited ability to filter these agents. But if you had an adequate filter, with a powerful fan and power source and some PVC pipe you could create a basic system.

Charlie Palmer -author, The Prepper Next Door: A Practical Guide For Disaster And Emergency Planning

Here’s a pdf about building a new home with radon in mind.

EPA’s Consumer Guide To Radon (pdf)

Here an news article about radon in Minnesota.

Here’s a great blog post on TNgun.com about the difference between negligent and accidental discharge of a firearm.

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