World Health Organization (WHO)
Launches
International Radon Project
JUNE 21, 2005, GENEVA -- In an effort to reduce the rate of lung
cancer around the world, the World Health Organization (WHO) is launching
the International Radon Project to help countries reduce the health risks
associated with radon gas. The Project will identify effective strategies
for reducing the health impact of radon, promote sound policy options for
countries and increase public and political awareness about the
consequences of exposure to radon.
Radon is a natural radioactive gas that emanates from the ground into
the air. Radon gas in the air is present worldwide, its concentration
depending on the highly variable uranium content of the soil. It is the
second most important risk factor for lung cancer, causing between 6 and
15% of all cases Yet, there is little public awareness of radon as a
threat to human health, that can be mitigated with relatively simple
measures.
"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 ionizing radiation, and accounts for 50% of
the public's exposure to naturally-occurring sources of radiation in many
countries."
Although the average exposure to radon varies enormously, recent
studies have shown that, when exposed to a radon concentration of 100 Bq (Becquerels)/m3,
a non-smoker's risk of lung cancer by age 75 years increases by 1 in a
1000 compared to non-exposed persons. (Note: 100 Bq/m3 = 2.7 pCi/L) Among
those who smoke and are exposed to the same radon concentration, the risk
of lung cancer is about 25 times greater.
On a global level, tens of thousands of lung cancer deaths annually can
be attributed to radon. Most of the radon-induced lung cancer cases occur
among smokers. Radon is a chemically inert, naturally occurring
radioactive gas without odour, colour or taste. It is produced from radium
in the decay chain of uranium, an element found in varying amounts in all
rocks and soil. Radon gas escapes easily from the ground into the air and
emits heavily ionizing radiation called alpha particles.
These particles are electrically charged and attach to aerosols, dust
and other particles in the air we breathe. As a result, radon progeny may
be deposited on the cells lining the airways where the alpha particles can
damage the DNA and potentially cause lung cancer. Due to dilution in the
air, outdoor radon levels are usually very low.
Radon can also be found in drinking water, the concentration depending
on the water source, and this can sometimes present a hazard. Radon levels
are higher indoors, and much higher radon concentrations can be found in
places such as mines, caves and water treatment facilities, and an
increased lung cancer risk has been found in uranium miners.
For the average citizen, by far the greatest exposure to radon comes in
the home. The concentration of radon in a home depends on the amount of
uranium producing the radon in the underlying rocks and soils as well as
the routes available for its passage into the home and the rate of
exchange between indoor and outdoor air.
Radon gas enters houses through openings such as cracks at concrete
floor-wall junctions, gaps in the floor, small pores in hollow-block
walls, and also sumps and drains. Consequently, radon levels are usually
higher in basements, cellars or other structural areas in contact with
soil, and the radon concentrations in houses directly adjacent to each
other can be very different. Radon exposure in homes can be easily
mitigated during the construction of new homes, but existing buildings can
also be protected from radon.
Most measures such as increasing under-floor ventilation and sealing
cracks and gaps in the floor require simple alterations to the building,
but other approaches may have to be taken in areas with high radon
concentrations. Overall, reducing radon exposure is an important
contribution to the goal of good quality indoor air.
The project is initially expected to run for three years (2005-2007).
As a first step, the WHO International Radon Project is setting up a
global network of radon scientists, regulators and policy makers to
collaborate in the project. Coordination will be provided by WHO. Working
groups will focus on risk assessment, exposure guidelines, measurement and
mitigation of radon levels, investigations of cost-effectiveness and risk
communication.
WHO guidelines based on this work will help national authorities to
develop, promote and strengthen activities at country or regional level.
The WHO fact sheets produced in the course of the Project will be a
central communication tool to increase public awareness about radon. The
WHO International Radon Project also aims to create a global radon
database and provide improved global estimates of the disease burden
associated with radon worldwide.
Overall, together with global tobacco control activities and
initiatives on healthy indoor air, the Project is expected to be a key
step towards reducing lung cancer risk word wide.
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