Radon exposure to come under WHO's microscope
The effects of a radioactive gas on people living in 20 different countries will be studied by the World Health Organisation (WHO) over the next three years.Radon is a naturally occurring gas that seeps out of the ground and can be found in varying concentrations all over the world.
It is blamed for tens of thousands of deaths every year and is thought to be the cause of between six and 15% of lung cancers, making it the largest risk factor after smoking.
For most people, the greatest exposure to the gas comes when they are at home, as once outdoors it disperses and is rarely found in high concentrations.
It is produced by the decay of radium, which can be found in almost all soils, and emanates from the ground, so can usually be found at greater levels in basements or at ground level.
It is chemically inert, colourless and odourless but attaches itself to dust, aerosol particles and other airborne matter which is then breathed in.
It emits radioactive alpha particles which can be deposited on the cell linings of our airways and potential trigger lung cancer.
Although it is relatively simple to protect a property from the gas a lack of public awareness means this often does not happen.
"Radon poses an easily reducible health risk to populations all over the world, but has not up to now received widespread attention," said Dr Mike Repacholi, coordinator of WHO's Radiation and Environmental Health Unit.
"Radon is all around us. Radon in our homes is the main source of exposure to ionising radiation and accounts for 50% of the public's exposure to naturally-occurring sources of radiation in many countries."
The WHO project is expected to run until 2007 and will initially see a global network of scientists, regulators and policy makers from 20 countries established.
The network will set up working groups to look at risk assessment, exposure guidelines, monitoring and mitigation of radon levels and cost effective ways to raise public awareness.
WHO also hopes to set up a global radon database to map the concentration of the gas around the world and examine how this impacts on the levels of lung cancer.
Experts believe the key to reducing risk for the vast majority of people is to make sure they have healthy air indoors.
There are a number of ways to reduce radon concentration indoors, including better ventilation to stop it building up, sealing floors and walls against the gas or installing a radon sump in the basement.
By Sam Bond