Radon exposure and health
In Australia, radon exposure is generally lower than the worldwide average. Increased exposure is associated with an increased risk of developing lung cancer.
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Radon is a naturally occurring radioactive gas, which has no smell, colour or taste. It comes from the radioactive decay of radium, which is present in small amounts in rocks and soil. Radon is chemically inert, so it can easily escape from the ground into the air where it can be inhaled.
Radon releases radioactive particles when it decays. When we breathe in radon these particles can cause damage to the lung tissue. Such damage can lead to lung cancer. There is a delay of many years between the initiation of a cancer by radiation and its growth to a size which can be observed clinically. The risk of developing lung cancer from exposure to radon depends on how much radon we breathe in. The more radon there is in the air, the bigger the risk. Similarly, the longer we spend breathing in that radon, the bigger the risk. There is also scientific evidence that smoking increases the risk associated with exposure to radon.
Radon is present in all air. In outdoor air, radon concentrations are very low. Indoors the concentration of radon can be higher, as buildings have the effect of trapping radon. Radon levels are highly variable, depending on the type of house and the flow of air through the home. There are places where radon levels can be very high: in some caves, for example, or in a poorly ventilated underground mine.
The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has conducted a nationwide survey of radon in homes. The results showed that the average concentration of radon in Australian homes is low, and is about one quarter of the worldwide average. Consequently, there is little cause for concern that the health of the population is at undue risk from radon in homes. However this survey did find that approximately one in a thousand homes may have high levels of radon. Generally, homes that are well ventilated, made of timber or built on stumps have lower radon levels compared to homes on concrete slabs with brick walls. However, the only way to be certain of radon levels in your home is to get it tested. Radon monitors are available for purchase from APRANSA.
ARPANSA recommends the following reference levels:
- 200 Bq m⁻³ for households
- 1000 Bq m⁻³ for workplaces.
Should the radon level exceed the above levels, the appropriate state, territory or Commonwealth radiation health authority should be contacted for advice. For those homes and workplaces that exceed this reference level, there are some simple measures that can be taken to bring radon levels down, such as increasing ventilation.