[Greenbuilding] Radon

[Lawrence Lile]

I've recently had to go through radon testing in some rental houses, and learned a lot in the process. 
 
Radon relates to Green building because radon is an insidious indoor air pollutant.  Tighter houses that began to be constructed in the 1970's began to concentrate indoor radon more than old leaky ones did.  Awareness of this problem is not more than 30 years old, and really in the last ten years has it been even considered widely. 
 
Radon was discovered as a problem in homes when a nuclear plant worker inadvertently wore his radiation dose badge home. His house was hot!  After the guys in moon suits, who figured he'd brought home some radioactive material fromt he plant, got done, they realized his house had a high level of naturally occurring radon, which is radioactive.  Then they tested his neighbors house, and it was hot, and tests houses throughout the town, and a big fraction were hot, and within a few years realized there was a national problem.  
 
OK how big a problem?  A smoker, who lives in a house with 20 pC/L of radon for many years, has a risk of 250 per 1000 of getting lung cancer.  That's pretty bad!  The risks go down for nonsmokers, and go down even more for lower levels of radon.  4 pC/L is the minimum action level, where lung cancer risks are not much different than where there is no radon.  
 
Any new construction *should* have at least a passive radon reduction system installed (so-called "radon-ready") and have a radon test after construction is complete.  There are no laws or codes about this, but it is becoming common to see buyers requiring radon tests.  It is a lot easier to build during construction than to retrofit.  I would consider it a vital part of a Green home.  
 
We installed an active radon reduction system last weekend.  It was actually quite simple - a pipe to the gravel under the slab, 4" PVC (shudder) pipe to a small, low power fan, and then an exhaust pipe to a bird screen up under the eaves.  Slap on a label, and there you go.   Contractors charge $1000 to $2000 for such a system, which uses about $200 in parts.  
 
I was surprised how much air was blowing out the top of the exhaust pipe.  There must be quite a number of cracks under a typical older slab, to allow air to flow so freely.  There is probably a big hole under the tub, and gaps at some plumbing penetrations, as well as cracks int he basement floor and around the edges.  
 
Lawrence Lile