Radon is a radioactive gas with the designation Rn-222. It is formed when radium decays. Radium is formed from uranium that is naturally present in the bedrock and soil. Radon has a half-life of 3.8 days, which is long enough for radon to be transported to indoor air. When radon decays, other radioactive substances are formed, known as the radon progeny. Radon cannot be smelt, tasted, or seen. The only way to detect radon is to measure it.
Long-term exposure to high levels of radon increases the risk of lung cancer. After smoking, radon is the most common cause of lung cancer. If you smoke or have previously smoked, your risk from radon is even greater than for non-smokers. The risk of lung cancer increases linearly with radon levels. This means that the higher the radon content, the greater the risk of developing lung cancer. In the UK, an estimated 1,100 people are affected each year by lung cancer due to radon in indoor air.
It can take 15 to 40 years to detect lung cancer after initial exposure to radon. By lowering radon levels in homes with radon values above 200 Bq/m3 to levels of around 100 Bq/m3 or lower, it is estimated that around 400 cases of lung cancer could be avoided in the UK in the long term. Lung cancer is the only known health risk of radon.
A good first measure in protecting yourself against radon is to measure the presence of radon in your home and workplace. In this way, you can identify if you are in an environment with high levels of radon. If it transpires that you are in an environment with excessive radon levels, it is important to lower them. In the United Kingdom, the target value for radon in the indoor air is no more than 100 Bq/m3.
If radon levels in your home or workplace are too high, you should enlist a radon consultant to identify the source of the radon. You can then take action to reduce the level of radon. It is important to use a company that specialises in lowering radon levels and has staff with documented expertise.
It is primarily radon’s short-lived decay products, known as radon progeny, which are harmful to health and damage the lungs. The decay products attach themselves to other particles in the air to form small particle clusters of varying size. These particles are then inhaled and get stuck in the lungs, where they decay before the body can clear them out.
Radon and its decay products emit alpha radiation, making them harmful when they enter the body. If there is radon in the air, there are also short-lived decay products there. Although it is the decay products that are most harmful, it is the radon gas content that is measured as it is easier to measure.
Radon can get into our indoor air from three different sources: the soil around and below the property, building materials, and household water. Ground radon is the predominant source of radon in apartment buildings, workplaces, and single-family homes. The air in the soil in the UK almost always has high levels of radon, typically between 5,000 and 200,000 Bq/m3. Indoor radon content depends on several factors, including the radon content of the air in the soil, the air permeability of the soil, the pressure difference between the indoor and outdoor air, and the penetrability of the building vis-a-vis the ground.
The measurement of radon in indoor air should be performed:
Radon can have one or more sources, so there are various means of reducing radon levels. In some cases, minor intervention is enough to bring about a reduction. Sometimes, several different measures need to be combined.
If the radon source is the ground, in some cases it may be enough to seal cracks and other sources of penetration in the basic structure of the building. If this is insufficient, negative pressure beneath the house can be created so that air in the soil is not sucked in. There are different methods to achieve this, including radon suction and radon pits. These measures may be combined with improvements in the building’s ventilation. Radon suction is probably the most common measure against ground radon. A unit is installed that reduces the air pressure in the ground under the house so that air is not drawn in from the soil. This negative pressure is created using a fan that sucks air out from one or more points under the concrete floor. Radon pits are primarily intended for use in air-permeable land, such as gravel ridges. The radon pit reduces the air pressure in a large volume of ground, meaning that the whole unit can be placed underneath the building.
If you need to reduce radon levels, you should enlist a radon consultant to identify where the radon is coming from and then suggest which measures are best.
To comply with Public Health England’s regulations, radon detectors from an independent, accredited (ISO 17025) laboratory should be used to measure radon. The radon measurement process should last for at least three months. The longer the measurement period, the more accurate the results. Measurement is the only way to detect radon. Levels often vary greatly day by day and season by season. Variations depend on such variables as temperature and wind conditions, ventilation systems, and how often you change the air. Consequently, long-term measurement periods of at least two months are required in order to estimate the annual average value.
If you need to conduct a quick radon measurement for an approximate value, such as when selling your home, you can perform a short-term measurement. This will measure radon levels for a shorter period of time. Measurements using a radon detector must last for a minimum of seven days. Short-term measurement is only advisory and cannot be used for any official decision.
A radon measurement should always be conducted when buying or selling a house. Since radon is not considered a hidden fault, the buyer must find out if the house has high levels of radon. Ensure that the measurement is conducted before buying the house and that you have access to the report.
If a quick radon measurement is needed, a short-term measurement can be carried out giving you an analysis response within two weeks. A short-term measurement is only advisory, however.
If there is no time for a radon measurement, request the insertion of a clause in the contract stating that you will conduct a radon measurement afterwards and specifying that the cost of any intervention is to be shared. If you have previously conducted a radon measurement, you have a duty to disclose this when selling.
Even in areas classified as having low-risk soil, radon is present in sufficiently high concentrations to pose a problem in indoor air. The air contained in the soil always has high radon levels. If the fabric of your home or workplace is penetrable and large amounts of radon in the air can get in, you may have high levels of radon in your indoor air. Note that there may be very large local variations and so two adjacent houses may vary considerably.
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