Radon Gas


November is here.  Many people do not realise that November is radon awareness month.  Some people have not even heard of radon.  Bookmark this page as I will be offering lots of information and advice concerning this subject that will allow you to make an informed decision on what sort of testing you feel is necessary, and what things you might have to do should you find excessive amounts of Radon gas.

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These won’t help you

What is Radon?

Radon is a colourless, odourless, tasteless cancer causing radioactive gas. It is found naturally in the environment and is produced by the natural but indirect decay of heavier radioactive elements like uranium and thorium commonly found in soils and rocks.

 

Technical stuff about Radon.

An element is made up of Atoms, which in turn are made up mainly of Protons (positively charged sub-atomic particle), Neutrons (sub-atomic particle with no electrical charge and slightly bigger than a proton) and Electrons (sub-atomic particle, slightly greater than 1/2000th the size of a proton, with a positive electrical charge).

Each element is given a designation and placed in a specific position in the Periodic Table of Chemical Elements. It has the chemical symbol Rn and sits in the area of Noble Gases in the Periodic table. The atomic number of an element, also found in the periodic table is given by the number of Protons in the elements atom. The atomic number of Radon is 86.

Some Elements like Radon have variances in their construction, because although they have the same number of Protons in the atom, they have a different number of Neutrons. This doesn’t mean their atomic number, or their position in the periodic table, changes, but it does mean their atomic mass changes. When this happens, the result is what is known as an Isotope of the element and is signified by the Chemical symbol for the element and suffixed by its atomic mass.Radon has 39 known Isotopes, Ranging from 193Rn to 231Rn,  the most stable of which is 222Rn. This means it has 86 Protons, 86 Electrons and 136 Neutrons. (86+136=222)

1000px-Alpha_Decay All of these Isotopes are radioactive. Something that is radioactive when an atom of the element chooses randomly to decay by emitting ionizing radiation including alpha and beta particles and gamma rays. This transforms the atom into a different type of atom, where a Neutron, Proton or Electron are lost or gained through electrical and/or nuclear interaction to create a different Isotope or even a different Element. The rate of decay of a single Atom cannot be calculated, because the decay is random, so the decay of an element is based upon a whole bunch of them together, and then measure in the time it takes for the Radioactivity to be halved.

This is known as the half-life of a radioactive element. Radioactivity is today measured in Becquerels per cubic metre (Bq/m3) (Named after Henri Becquerel). This tells us how many atomic disintegration events occur each second because of a radioactive decay process. Before the Becquerel became the internationally adopted standard for representing atomic decay, the decay was measured in Curies (Named after Marie and Pierre Curie).  In the U.S. Radiation is still measured in picoCuries per Litre of Air (pCi/L).

Health Risks.

UN-Radioactive-warningMany world-wide health organisations and governments, including Canada and the U.S., now recognise that radon is the second leading cause of lung cancer.  Because radon is a gas, it can easily move through small spaces in soils and other materials, allowing it to enter the air we breathe, both outdoors and inside buildings. In the outdoors, radon mixes with large volumes of fresh air and is diluted to low concentrations. However, if radon enters an enclosed or poorly ventilated space in a building, it can accumulate to levels that can pose a risk to health.

In 2007, Health Canada announced a revised guideline for radon levels in indoor air.  According to Health Canada the new guideline of 200 Bq/m³ makes Canada’s guidelines lower than or equal to most every other major industrialized country.

Is this good enough?

The World Health Organisation indicates that radon exposure is a major and growing public health threat in homes and recommends that countries adopt reference levels of the gas of 100 Bq/m³.

The U.S. Environmental Protection Agency (EPA) recommends that interventions to address radon be instigated when the level of radon measured inside a building exceeds 150 Bq/m³.

A European study involved nine countries, more than 7,000 individuals with lung cancer, and a control group of more than 14,000 individuals. The European study concluded that every 100 Becquerels per cubic metre (Bq/m³) increase in radon increases the risk of lung cancer by 16 per cent, and that there is clearly an increased risk of lung cancer at radon concentrations below 200 Bq/m³.

The guideline of 200 Bq/m³ is out of date.  When having a guideline that is recognised by modern studies as being too high, pronouncing your are the same as others does not make it right.

200 Bq/m³ is the level of the radon guidelines established by many countries twenty years ago and only relatively recently adopted by Canada. Recent North American radon studies published in 2005 make it clear that there is a significant increase in the risk of lung cancer from exposure to radon at concentrations of 100 Bq/m³, agreeing with the European study.

The risk of cancer due to radon exposure under the current guideline continue to be far higher than the level of acceptable risk for other chemical and radiological hazards in Canadian society.

We disagree with Health-Canada.  When the recognised average surface background radiation in outside air in Canada is around 24 Bq/m³, having an indoor guideline that is nearly 10 times that is ludicrous, especially as testing is cheap and mitigation is not terribly expensive.

Now it get’s really weird!

The strangest thing is, it’s not the radon itself that is hazardous.  Because it’s a gas, it is breathed in and out of the body, and therefore in itself radon poses no major threat.

The problem is that radon decays while it’s in the body and the isotopes have a relatively short half-life.  As part of the decay process the daughter elements that are formed are not gas, but heavy metals and are in themselves radioactive.   These radioactive metals are absorbed into the lungs as a process of breathing and once there decay further allowing the radiation to penetrate directly into the cells of the body that are unprotected by the skin.

The stRadson-decay-cycleuff spy films are made of

It is here, at decay stage of radon, that things get interesting.  The first daughter element of radon-222 is an isotope of polonium (218Po).  This is a highly toxic radioactive metal which absorbs into the body and has a half-life of 3.1 minutes.  For 3.1 minutes any polonium, including any absorbed into the lungs, emits large amounts of Alpha particles, for the next 3.1 minutes, half-as many, and the next 3.1 minutes half as much again and so on.  Alpha particles are natures radioactive bulldozers and will tear a fairly straight motorway clean through any organic tissue.  The cells damaged in this way either die or morph into something far more sinister, cells that are cancerous.  The problem is even after the polonium has broken down, it goes through a reciprocal stage of changing into radioactive isotopes of lead, then bismuth, back into polonium-214, and through the cycle again to polnoium-210. Each of the polonium cycles release more and more Alpha particles.

Indeed, it is believed that the Russian secret service have used polonium, maybe through radon dissolved in drinks or salad dressings and oils, to successfully assassinate more than one dissident.

What if radon is found?

You cannot stop radon from being produced.   It has been happening for millions of years, but there are ways of stopping it from coming into the home.  Unfortunately these are expensive one the house has been built.  Vapour barriers are not sufficient to stop radon which will permeate through.  A full air barrier is required, which means totally enclosing the crawlspace or basement in an impermeable membrane.  Obviously this is nearly impossible if your home has already been built.

So the next best thing is to ensure that where the radon is entering is restricted as much as possible to limit the entry of the gas, and then ensure that it is removed from the property as quickly as possible.

The fastest way to minimise radon concentration is to forcibly ventilate the areas where it might be entering the home.  This is usually from below, either in the crawlspace and the basement.  For homes with sumps and sump-pumps radon can enter through the underground water.  Providing a forced ventilation system that ejects the air in the basement out through ventilation pipes is the quickest, easiest and cheapest method to mitigate the hazards posed by radon and it’s derivatives.

A free PDF download is available from Health Canada and for your convenience you can download it here.

Health Canada Survey

RadonPotentialMapGH-NPIn a fairly recent Health-Canada survey, radon sampling devices were sent out to volunteers who wished to test their properties. In the area we service for Indoor Air Quality (IAQ) and Healthy-Home Inspections, the results were quite surprising.

In the areas of Oakville & Burlington almost 5 out of every 100 homes tested had Radon levels above the lower limit recommended by Health-Canada.  The same applied to the Hamilton Area.  In Brant county the findings indicated over twice that amount.  In Haldimand the count was lower at just under 3 in every 100 home.  In Niagara Region it was the same, but the Radon levels were much higher, in excess of the old recommended lower limit.

A summary of the full report which can be found here is shown in the table below.

Health Region Name %
Below
200
Bq/m3
%
200 to
600
Bq/m3
%
Above
600
Bq/m3
%
Above
200
Bq/m3
Halton Regional Health Unit 95.1 4.9 0.0 4.9
City of Hamilton Health Unit 95.0 5.0 0.0 5.0
Brant County Health Unit 89.6 9.4 1.0 10.4
Haldimand-Norfolk Health Unit 97.4 2.6 0.0 2.6
Niagara Regional Area Health Unit 98.0 0.0 2.0 2.0

Where does the radon come from?

To understand the radon – we need to understand a little about the genealogy of radon, where it forms, how it forms, how it moves.   For this we have to start at the ultimate source uranium and a little about geology (the study of rocks)

All rocks contain some uranium, although most contain just a small amount – between 1 and 3 parts per million (ppm) of uranium. In general, the uranium content of a soil will be about the same as the uranium content of the rock from which the soil was derived.  So if a rock formation was high in concentration with uranium, the likelihood is that soil derivative of those rocks would be high in uranium also.

In the table below we can see that the levels of uranium in soil varies depending upon the type of rock.
Uranium-originsHere in Canada, we can find uranium in a number of types of rock deposits.

Unconformity-related deposits.
An unconformity is time gap in the rock record between two rock units where the lower unit may be deformed, brecciated or altered and the overlying units are less deformed. Uranium deposits can occur in the underlying or overlying units. In the underlying units, there may be a weathering zone, fault zone or some other feature that increases the rocks porosity and permeability. In the overlying units, it maybe the sand-stones or some other features that allows the concentration of uranium.

Sandstone & Conglomerate deposits.
Normally found in the coarser fraction of sand-stones and conglomerates, these units are typically deposited in marginal marine to terrestrial environments. The largest deposits are found between impermeable units and contain abundant organic debris or other material to promote the reducing conditions to cause the uranium to precipitate out of solution.

Surficial deposits.
The uranium here is concentrated in young sediments or soils near the earth’s surface. Uranium minerals precipitate out onto the finer-grained particles or are transported particles. This is associated with soil formation.

Volcanic deposits.
These are deposits are that associated with fault, fracture and shear zones in acidic volcanic rocks.

Intrusive deposits.
These are found in intermediate to acidic igneous rocks and pegmatites, the uranium-rich minerals are direct precipitates

rockformationNiagara Falls and the Niagara Escarpment.

The Niagara Escarpment is recognized as one of the world’s unique natural wonders. Essentially, it is a land-form — a ridge of rock several hundred metres high in some locations — stretching 725 kilometres (450 miles) from Queenston on the Niagara River to Tobermory at the tip of the Bruce Peninsula. Today, in Ontario, the escarpment contains more than 100 sites of geological significance including some of the best exposures of rocks and fossils of the Silurian and Ordovician Periods (405 to 500 million years old) to be found anywhere in the world.

Uranium deposits are frequently found in It is likely that many of the Silurian rocks contain uranium deposits in some quantity to produce radon, but not sufficient to be considered worth mining.

The recent Health-Canada Survey, which although not exhaustive does show that this hypothesis is possible as the level of radon in the Niagara Region was found to be in the 200-600Bq/M3 bracket.

How does uranium become radon and then into your home?

Uranium doesn’t move except when there’s a volcanic reaction, or an Earthquake and the rocks from well below the surface are pushed up.  But uranium, being radioactive does stay as uranium.   It changes through nuclear decay into other elements.  And it doesn’t do this overnight.  Uranium will eventually turn into lead, but in order to get there it has to go through many stages of decay, each cycle releasing alpha and beta particles, and gamma radiation.  the first stage is from uranium238 into thorium234 and that takes 4,500 million years to only change half of it. Each subsequent half of the uranium takes another 4,500 million years to change the next 1/2, and so on.

But then what?

Well the next set of processes happen relatively fast.  From thorium to radon it only takes 317,600 years or so.  Yet again each new element is a solid, and doesn’t move from where it was formed, billions of years ago.

Here’s the problem.  Radon is a gas, and the isotope of radon that comes next (radon222) is still radioactive.  This gas, although heavier than air, is still less dense than the rocks around it, and is driven, quite rapidly, to the surface by a combination of pressure and advection.

Studies have shown that at or around 3m below the surface the pressure and advection currents pretty much balance the atomic weight of the radon222 and it’s ascent slows to a trickle.

Stack EffectThat is until we dig a hole in the ground and put a basement into it, and a house on top!

Then we are not only lowering the resistance to the radon by digging down into the balanced area, but we are adding what is essentially a vacuum cleaner on the top of the soil which literally sucks the radon from the soil by the stack effect of the house.

Get tested!

As can be seen from the radon potential map of Ontario radon can appear anywhere.  The tighter and more energy efficient your home, the more likely it is to have higher concentrations of radon where it exists.  In parts of countries such as the U.S. and U.K. mandatory testing by sellers is already in place, and it is only a matter of time before this permeates to Canada.

To quote the David Suzuki foundation

“In an era where international harmonization is recognized as an important Canadian objective, particularly in the North American context, there is no justification for failing to match the American guideline. There is no reason why Canadians should receive an inferior level of protection than Americans.”

It makes sense.   Radon is a known cause of lung cancer and represents a major public health burden, both in human and economic term.

Health-Canada only approves long-term testing to initiate mitigation of radon.   At Future Proof Property Inspections we believe this is wrong.   The surveys instigated by Health-Canada used short term devices.   The U.S. use short-term devices for realty transactions, the U.K. and the rest of Europe approve short-term devices to indicate the presence of radon.   Here in Ontario the Ministry of Government and Consumer Services, working with the Tarion corporation have approved the use of short-term devices to initiate a claim against the Tarion warranty program, backed up by a long-term sampling.

It is wrong to expect Canadians to have to wait 3 months or longer to find out if they are possibly exposed to radon concentrations that are considered more dangerous than need to be.

Our services

At Future Proof Property Inspection we offer our client both short-term and long-term testing.  The short-term allows us to provide you with a faster answer to your questions “Do I have radon in my home and is it dangerous?”.  The long-term satisfies Health-Canada’s dubious policy but takes at least 3-moths to complete.

No conflict of interest!

As with our Mould sampling services, we do not provide  mitigation services, and therefore our tests are completely independent of any profit that could be made by telling you the levels are high, and then getting the job to fix the problem.

You can be sure, if you follow the protocols we advise you of during our consultancy session, you will always get an accurate response from us with no conflict of interest possible or otherwise.

CA-LS Device-sml

Dual canister short-term sampler

Our short-term measurements are always carried out using twin devices.

You get a two-for one solution, with the sampling being performed by a qualified inspector and tested via an approved laboratory with guaranteed results.

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