You raise two very good points:
Risk is a number, and that number is never “zero.” Risk is merely a probability of an occurrence. As such, each human in the US and Canada have a risk (probability) of 1E-7 of not living through this day. That is, the total combined causes of death (crime, motor vehicle accidents, disease, age, etc) means that any randomly selected human has a 1 in 10 million chance of dying today. Now, 1E-7 is a small number (0.0000001), but it is not “zero.” As such, there is never anything as “no risk.”
Consider the probability (risk) of getting hit by a meteor – it was reported that 1,000 people were injured on Feb. 15, 2013 around Chelyabinsk, Russia when a 7,000 ton meteor exploded on entry. Although I have not double checked the reference, it is reported that Phil Plait (a.k.a., “The Bad Astronomer”) calculated a risk of getting hit by a meteor was 1 in 700,000 (which is 1.4E-6)… again a small number but not zero. Now could you reduce the risk even further by wearing a steel hat and armor plate whenever you go outside? Could you reduce the risk even further by never going outside? Could you reduce the risk even further by living 4km deep within the Mponeng gold mine? Of course you could – but why would you, just to reduce the risk of getting hit.
Whereas risk is objective, then the number is low enough, we encounter a subjective threshold called “safety.” That is, “safety” is the attainment of an acceptable level of risk. Risk is objective, and safety is the irrational acceptance of a specified level of risk.
So, when someone wants to install a “radon mitigation system” to avoid the measly 225mrem/year of radiation, I would pose to them the following question: “Just how safe do you want to be?” And why, then, if you are worried about radon in your home, are you willing to drive to the grocery store and get milk (which carries five times more risk of death than radon in a home). Or indeed, why are you willing to live in South Carolina, instead of Tennessee, since living in SC carries ten times more risk of death than living in Tennessee. Why are you going to spend $2K dollars installing a radon mitigation system in your home, but you are doing nothing about removing the ambient benzene form your home, that carries far greater risk of cancer than does radon? What about the 100 mrem you are about to receive by flying out to California to see your great Aunt Agatha?
The answer lies in “fear.” People don’t fear driving to the store, because it’s a familiar risk – even though every one of us has driven by numerous horrific motor vehicle accidents (MVA), and each of us has personally seen the blood and guts and death, and probably personally know someone who has been killed in a MVA, yet probably none of us has see someone who was killed by radon – Similarly, one chooses to live in South Carolina or Georgia because those are nice places, and the fact that living in those states versus living in Nebraska, or Oklahoma increases the risk of death ten times greater than radon never enters people’s minds. Why? Answer: Awareness. The general public has been unnecessarily frightened out of their wits with irresponsible statements from various government entities wherein the risks are neither put into perspective and are not based on science.
If 4 pCi/l of PAEC (radon) results in a significant risk because a radioactive disintegration may occur at a cellular level, then consider this: If you are an average US adult, you have about 150 grams of potassium in your body right now. As you sit and read this post, you are irradiating about 4,400 Bq (120,000 pCi) of just the K40, (that equates to about 4,400 radioactive disintegrations per second). And that’s just from the potassium! And that occurs in your body each second you live.) At least 98 % of those disintegrations take place within body cells, and are potentially capable of altering the cell's DNA. So why aren’t you dead from cancer – indeed, why didn’t you die from cancer before the age of 2? Our own bodies irradiate us with ionizing radiation, at a rate of one fifth of that the average US citizen receives from radon (when we express the exposure as “dose” in mrems per year).
Answer – because, as of today, February 3, 2016, there has not been a single valid study ever performed on the face of the earth, devoid of confounders and unsupportable assumptions that has ever shown with confidence that radon, as typically encountered in homes increases the risk by an single iota. Indeed, most of the legitimate epidemiological studies performed thus far, show that the cancer rates in homes with low levels of radon are LOWER than the cancer rates in homes with no detectable levels of radon. To be clear, the majority of legitimate studies show that, at levels typically encountered in homes, as the radon concentrations go up, cancer rates go DOWN.
However, whether this is a statistical anomaly or not, I don’t care because either way, we are dealing with risks that are vanishingly small, and entirely insignificant, even if they are real.
So, as I sit here in my office in Bailey, Colorado, writing this post, I think of the poor souls in Denver where the cosmic radiation pours down some 2,000,000,000,000,000,000 high energy protons (each greater than one billion eVs) every second, and are receiving about 0.02 mrem every HOUR! Do I gasp at the fact that my office is at 9,000 feet elevation where my hourly dose may be as high as 0.04 mrem/hour? No. I don’t gasp – Indeed, later today, I will drive about 125 miles which will swamp the risk of NORMs in my environment. That’s risky. Indeed in my case, I also happen to be part-time police officer, and so later today I will don a ballistic vest, holster a gun and face the world as it presents itself to me. Should I worry about radon as I drive around in a marked patrol car? Probably not; currently I am much more concerned about the spider on the ceiling directly above me – now THAT’s frightening! But am I "safe"?
Perspective
Perspective
Perspective
Cheers!
Caoimhín P. Connell
AMDG