Tag Archives: radon gas

Radon Safety Inspections: More Interesting Facts You Didn’t Know

Some of you are aware from reading my blog or elsewhere that radon gas exposure is estimated to cause 15,000 – 20,000 deaths in the United States but is even more likely to affect smokers.

But how much more?

As of this writing it is estimate that radon is responsible for 3-5 % of all fatal lung cancers, but specifically up to 10-15 % for smokers.

In the chart below, you can see that radon gas contributes the majority (over 1/2) of the harmful radiation that an average person is exposed to over their lifetime including medical X-Rays.

Radon Gas Overall Contribution Chart

Radon Gas Overall Contribution Chart

Where does the radon gas come from?

Much of it is from soil exposure, but a sizable contribution within indoor dwellings comes from building materials such as brick, concrete, etc. and particularly stone such as mildly radioactive granite and marble which are found in kitchen and bath counter-tops. (ScanTech can test natural stone materials for excess radioactivity) Other potential sources are in the water and natural gas supplies; even in burning coal.

Radon is soluble in water, particularly cold water and can be released while cooking, bathing and cleaning. It can also find it’s way into the breathable atmosphere through commercial activities such as ore processing, burning of coal in power stations and the use of agricultural fertilizers.

Radon Safety Inspection Inspector Dallas

Radon Safety – Indoor Dwellings Contribution Pie Chart

One interesting property of note with radon is that is has a rather strong diffusion ability, which means that it spreads out and infiltrates air and water easier than many other substances. The official diffusion coefficient is 0.12 cm^2/sec in air and 1.37 * 10^-5 cm^2 in water at 25 C. (roughly room temperature)

The solubility coefficient is the measure of gas solubility in water. It is defined as the ratio of the radon concentration in water to that in air. At 20 C, the solubility coefficient is 0.25 which means that radon is distributed preferentially in air rather than in water. (a ratio of 4:1) The radon solubility is 510 cm^3/L at 0 C as the solubility of radon goes up in colder water. (this is rather the opposite of most other chemical substances where the solubility tends to go up the warmer the water)

More Interesting Facts About Thorium and Radioactivity

While the radon decay series is well documented on the Internet, the thorium radioactive series is hardly mentioned so I have included it here for convenient reference.

 

Thorium-232 Decay Series

Thorium-232 Decay Series

Incidentally, alpha particles are the most effective ionizing agents but generally cannot penetrate very far into any material (even in air it loses energy at the rate of about 1 MeV per cm) so that must be internalized in the body to do harm. An alpha particle would require at least 7.5 MeV of energy to penetrate skin due to the top layer of the epidermis being composed of dead cells.

Only Polonium 214 at 7.69 MeV emits alpha particles energetic enough to penetrate the skin. (it is suspected of being the cause of skin cancer in miners) However once inside the body (such as through inhalation) a 5.5 MeV ejection energy can penetrate about 40 um into soft tissue which is about the length of 4 cells.

But the alpha particle would have produced about 160000 pairs of ions before it loses all of its energy. In comparison, this is about 40000 ion pairs per cell versus an average of about 60 ion pairs produced by a 2 MeV beta particle.