Radon - frequently asked questions

What is radon and where does it come from?

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. As a gas, radon can easily escape from the ground into the air where it can be inhaled.

How does radon affect health?

When we breathe in radon, it decays releasing radioactive particles. These particles can cause damage to the lung tissue. Such damage can lead to lung cancer many years after exposure. The risk of developing lung cancer from exposure to radon depends on two factors. How much radon we breathe in and how long we spend breathing in that radon.

What is my risk of lung cancer from exposure to radon in Australia?

Globally exposure to radon is the second leading cause of lung cancer, and the risk is significantly higher for tobacco smokers than for non-smokers. The risk of lung cancer from radon exposure is estimated to be 25 times greater for persons who smoke tobacco, as compared with those who have never smoked.

The World Health Organization (WHO) estimates that radon causes between 3% and 15% of lung cancers worldwide. The low levels of radon in Australian homes means that radon is likely to cause a few percent of lung cancers. The best way of reducing the risk of developing lung cancer is to never take up smoking, or to quit smoking as soon as possible. For the non-smoking Australian population, the risk for lung cancer associated with radon exposure is very small or manageable.

Why is tobacco smoking a concern?

Tobacco smoking remains the most important cause of lung cancer. There is now sufficient evidence that a smoker who is also exposed to radon has a much higher risk of lung cancer. The best way of reducing the risk of developing lung cancer is never to take up smoking, or to quit smoking as soon as possible.

Where can I be exposed to radon?

Day-to-day life at home and at work inevitably leads to some exposure to radon. 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 vary depending on the type of house and the flow of air through the home. There are places where radon levels can be high: in some house basements, tourist caves, or in poorly ventilated underground mines.

Why is the risk assessment approach changing?

Our understanding of health effects from radon exposure began as early as the 16th century when a wasting disease in miners was first recognised. Today we know that this was due to very high levels of radon in poorly ventilated environments. Over the last 50 years, significant research has allowed continuous improvement of how health impacts from radon exposure are estimated. The recent changes in the dose assessment methodology for radon has resulted in the risk from radon exposure approximately doubling. See ARPANSA advice on changes to dose assessment approaches for radon.

Are children more at risk from radon exposure?

Yes. Children are more sensitive to radiation than adults. Children also have faster breathing rates than those of adults. Therefore, the risk of lung cancer in children resulting from exposure to radon is higher when compared to adults exposed to the same amount of radon. If children are also exposed to tobacco smoke, the risk of getting lung cancer further increases.

What are the radon levels in Australian homes?

A nationwide survey of radon in homes in the 1990s showed that the average concentration of radon in Australian homes is low, and is about four times less than the worldwide average. Consequently, there is little cause for concern of health effects from radon in homes. However, this survey did find that approximately one in a thousand homes might 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. The only way to be certain of radon levels in your home is to get it tested. Radon monitors are available for purchase from ARPANSA's Personal Radiation Monitoring Service.

For more information on radon levels in Australian homes, contact the radiation regulatory authority in your state or territory.

Can I measure radon in my home?

Yes. Our senses cannot detect the presence of radon, it is odourless. Measuring radon is the only way to determine levels. Radon monitors are used to measure average radon levels. Monitors are placed about 1 to 1.5 metres above the floor and away from walls in the area of the home where people spend most of their time. These radon monitors must remain in place for a minimum of 3 months to a maximum of 12 months. These monitors will not display a value in real-time. The monitor is analysed upon return to ARPANSA and a test report is issued. Radon monitors are available for purchase from ARPANSA.

For more information on radon levels in Australian homes, contact the radiation regulatory authority in your state or territory.

Can I reduce radon levels in my home?

Yes. The level of exposure is highly dependent upon individual behaviour. The role of self-help protective actions is therefore crucial. Stopping tobacco smoking or avoiding tobacco smoke will reduce your risk of lung cancer. If measurements of radon in your home are above levels of concern, then some simple measures can be considered. Radon levels in existing homes can be reduced by:

- increasing under-floor ventilation;
- avoiding the passage of radon from the basement into living rooms;
- sealing floors and walls; and
- improving the ventilation of the house

For more information on radon levels in Australian homes, contact the radiation regulatory authority in your state or territory.

When should I take action to reduce radon levels in my home?

The ARPANSA radon test report will provide advice on the level of radon in your home and compare it to a derived reference level for action to be considered. ARPANSA recommends action to be considered it radon levels are above 200 Bq m⁻³ for households. This also applies to most workplaces.

For more information on radon levels in Australian homes, contact the radiation regulatory authority in your state or territory.

How do I manage radon in my workplace?

In most workplaces, radon exposures of workers is not a result of their work activities. Therefore, they are not considered to be occupationally exposed. ARPANSA provides detailed guidance on how to treat radon in the workplace in the following Guide for Radiation Protection in Existing Exposure Situations, RPS G-2. The guide describes when you need to make a decision to manage your radon levels. ARPANSA recommends action to be considered if radon levels are above 200 Bq m⁻³ for most workplaces. This is the same for households.

If radon levels exceed 200 Bq m⁻³, the preferred option is to reduce the level of radon, for example, by improving ventilation. If this is not possible, optimising protection is recommended, for example, by reducing occupancy.  

For exposures in workplaces that persist above the derived reference level of 1000 Bq m-3, workers should be considered as occupationally exposed. In such cases, the application of the relevant clauses for occupational exposure in planned exposure situations as described in the Code for Radiation Protection in Planned Exposure Situations, RPS C-1 apply.

For more information on radon levels in workplaces, contact the radiation regulatory authority in your state or territory.

How do I measure radon in my workplace?

ARPANSA provides a radon monitoring service to assess occupational exposure to radon. Radon monitors can be used as an area monitor or worn as a personal monitor. If used as a personal radon monitor, they are worn like a badge on the chest. If used as an area monitor, they are simply placed on a flat surface 1 to 1.5 metres above the floor in the area requiring to be monitored for the entire monitoring period. ARPANSA provides advice on ‘Who needs to be monitored’ and further service information can be found on our Personal Radiation Monitoring Service webpages.

For more information on radon levels in workplaces, contact the radiation regulatory authority in your state or territory.

What are the radon levels in Australian underground uranium mines?

Miners’ long-term exposure effects to radon are well known. In Australia, radon levels in underground uranium mines are typically low because of good engineering controls and ventilation practices. When all ionising radiation exposure pathways are considered, including inhalation of radon, radiation doses to workers are low and are well below limits.

There is always a need to remain vigilant on radiation exposures of uranium mining workers. Changes in the dose assessment approach for radon represents an improvement in the overall risk assessment to workers. However, the implications for workers’ health are minimal at the current radon exposure levels in Australian underground uranium mines. See ARPANSA advice on changes to dose assessment approach for radon.

For more information on radon levels in workplaces, contact the radiation regulatory authority in your state or territory.

What are the radon levels in Australian show caves?

An Australia-wide survey of radon levels in underground show caves found that about one fifth of the caves measured had elevated radon levels. At the time of the survey in 1996, the radiation doses to the tour guides in these caves from exposure to radon were assessed to be low. Changes in the dose assessment approach for radon represent an improvement in the overall risk assessment to workers. This means that radon inhalation doses for some show cave tour guides in the original study may exceed the derived reference level.

Consultation with the affected workers, employers and relevant regulators is needed to better understand the current situation and, if required, to devise strategies to minimise potential health risks while maintaining worker livelihoods.

While the radon levels in these show caves are relatively high, short-term exposure to members of the public during a guided tour of the cave represents negligible health concern.

For more information on radon levels in workplaces, contact the radiation regulatory authority in your state or territory.