Australian Radon Action Plan

Why does Australia need an Action Plan?

The International Commission on Radiological Protection (ICRP) has reviewed recent epidemiological studies of the association between lung cancer and exposure to radon and observed significant associations at elevated radon levels (ICRP, 2010). The World Health Organization (WHO) estimates around 4% of lung cancer deaths worldwide are attributed to exposure to radon found in homes and workplaces (WHO, 2017). The International Atomic Energy Agency (IAEA) recommends that governments 'establish and implement an action plan for controlling public exposure due to radon indoors' (IAEA, 2014).

The Australian Radon Action Plan presents a long-range strategy for reducing radon-induced lung cancer in Australia. This plan will initiate actions in four key areas:

1. Raising awareness
2. Assessing radon levels
3. Providing advice
4. Minimising radon exposure

What is Radon?

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 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. There are places where radon levels can be very high: in some caves, for example, or in a poorly ventilated underground mine.

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. 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.

What is the risk posed by Radon in Australia?

Relative to most other countries, the levels of radon in Australia are very low. Figure 1 indicates that mean indoor radon levels in Australia are the lowest amongst member countries of the Organisation for Economic Co-operation and Development (OECD). Therefore, on average, radon contributes less than one third of the total dose due to all sources of radiation in the Australian environment.

Based on the ICRP observation of a significant association between lung cancer and radon exposure at levels of approximately 200 Bq/m3 (ICRP, 2010), the following reference levels are recommended in Australia:

• 200 Bq/m³ for households
• 1000 Bq/m³ for workplaces

Figure 1: Average indoor radon concentration in OECD countries.

In most workplaces, radon exposures of workers is not a result of their work activities. Therefore, they are not considered to be occupationally exposed. It is recommended for action to be considered if radon levels are above 200 Bq/m³ for most workplaces. This is the same for households. Where these reference levels are exceeded, action should be taken to reduce the concentration of radon or the exposure of people to the radon.

An extensive survey, conducted by ARPANSA in 1990 (ARL, 1990), indicated that almost no Australian homes need to consider reducing levels of radon. Most workplaces are above-ground buildings with good ventilation. So, similar to homes, it is expected that most Australian workplaces would have very low radon levels. In the Australian context, there are only a limited set of scenarios that might give rise to  elevated radon levels:

• Highly energy efficient buildings in areas of high radon potential; or
• Underground workplaces; or
• Workplaces with elevated radon concentrations, such as spas using natural spring waters; or
• Enclosed workspaces with limited ventilation.

How will the risk posed by Radon in Australia be addressed?

The risk posed by radon in Australia will be minimised by taking action in four key areas:

1. Raising awareness and encouraging action
2. Assessing workplaces and public buildings that may have elevated radon concentrations
3. Providing advice and guidance to those workplaces and public areas that have radon concentrations exceeding the reference levels
4. Minimising radon concentration in new buildings in areas with high radon potential

1. Raising awareness

The potential health impacts from exposure to radon in the mining and milling of uranium ores and mineral sands have been of concern since the 1950s. Therefore, authorities responsible for radiation protection have regulated the exposure to radon of workers in those industries. However, the legislation regulating exposure to radiation does not extend to people exposed to naturally occurring levels of radiation. 

Previous assessments of the risk to people exposed to naturally occurring levels of radiation have determined that the risk posed by radon in Australia was very low. Therefore, the range of regulatory authorities responsible for public and workplace health do not currently consider controlling exposure to radon. However, the International Commission on Radiological Protection have recently re-evaluated its estimates of lung cancer risk for radon progeny and doubled its estimate of risk from exposure to radon (ICRP, 2010).

The regulatory authorities responsible for public and workplace health already have direct engagement with the broad spectrum of stakeholders that can manage public and workplace exposure to radon. Therefore, it is these bodies that should be engaged, through this Action Plan, to promulgate public and workplace awareness of the potential risks of radon exposure.

In particular, the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) will collaborate with Safe Work Australia, the Australian Government statutory body established to develop national policy relating to Work Health and Safety, to develop and publish a guide on radon exposure in the workplace.

2. Assessing workplaces and public buildings

In line with best practice in radiation protection and workplace health and safety, the strategy for dealing with radon in workplaces and public buildings should involve a graded approach to risk and a careful targeting of resources.

In the first instance, radon should be recognised as yet another potential hazard in the workplace and public buildings. Those responsible for the workplaces or public buildings should be encouraged to measure the concentration of radon to determine if it approaches the reference levels.

In Australia little is known about radon levels in public buildings. This presents an opportunity for the education sector to conduct radon measurement surveys in schools and preschools to better understand radon exposure and to introduce learning material into the classroom to raise awareness.

In Australia some underground show caves have been recognised as workplaces that have elevated radon levels. In 2019 ARPANSA undertook a reassessment of inhalation radon doses to Australian underground show cave workers (Solomon, 2019). Although the total number of show cave workers in Australia is very small, the reassessment indicates that radon exposure remains a significant radiation protection issue for operators and workers of show caves. 

ARPANSA has commenced work with the operators and workers of show caves to optimise protection against radon exposure for tour guides. This has involved site visits to educate workers and collaboration with operators to develop protection strategies and monitoring programs. ARPANSA will also explore cooperative arrangements with the mining industry to assess the levels of radon in underground mines.

3. Providing advice and guidance

Australians generally have a high level of anxiety about exposure to radiation. Therefore, managers of workplaces and public buildings found to have elevated radon concentrations will require carefully considered advice and guidance on the potential health impact of past exposure and methods to minimise future exposure.

This advice should be developed in conjunction with state and territory radiation safety regulators and be packaged such that managers have access immediately upon being advised of elevated radon levels.

In Australia, most remediation of elevated radon levels will comprise increasing ventilation in the building or workplace. However, there will be some cases where this is not possible or cost-effective. In such cases, a radiation protection specialist will need to work with the management of the workplace or building to develop specific strategies to minimise radon exposure. As community awareness increases and if there is a need control radon exposure, then regulatory authorities responsible for radiation protection will need to work with the radiation protection community to increase the number of services that can provide advice on radon exposure. By working with Safe Work Australia, ARPANSA can support the development of national uniform advice and industry-specific guidance on radon mitigation.

Through the development of a radon potential map, ARPANSA can display radon zones in Australia to identify areas with potential for elevated indoor radon levels in homes and workplaces. The map is intended to help governments and other organisations target risk reduction advice and guidance. Radon potential maps are developed using a combination of data on indoor radon measurements, geology, aerial radioactivity and other geological information.

4. Minimising radon levels in new buildings

Almost all of the houses surveyed in the 1990s had very low radon concentrations (ARL, 1990). This was due to two main causes, viz.:

1. Compared with that in some other nations, the geology in most areas of Australia does not produce very much radon. 
2. Most Australian houses built before the mid-1990s favoured a high inflow of outside air to cool the residents during summer.

With the advent of widespread air-conditioning, Australian building design is now favouring energy efficiency. A significant part of the efficiency gained is produced by restricting the exchange between the building and the air outside. This reduction in air exchange could lead to elevated levels of indoor radon in new buildings, particularly in those areas where the geology produces greater amounts of radon.

ARPANSA is committed to communicating with local governments in areas with high radon potential. This will alert local governments that new housing which aims to minimise air exchange to achieve energy efficiency may inadvertently elevate indoor radon levels.

Additional resources

Advisory Note - Exposure to Naturally Occurring Radon in the Workplace

References

ARL. (1990). A Nation-Wide Survey of Radon and Gamma Radiation Levels in Australian Homes. Australian Radiation Laboratory.

IAEA. (2014). Radiation protection and safety of radiation sources : international basic safety. Vienna: International Atomic Energy Agency.

ICRP. (2010). Lung Cancer Risk from Radon and Progeny and Statement on Radon.

Solomon, S. (2019). Reassessment of inhalation doses to workeres in Australian Show caves. Radiation Protection Dosimetry, 184(3-4), 298-301.

WHO. (2017). Preventing non-communicable diseases (NCDs) by reducing environmental risk factors. Geneva: World Health Organization.