Transcript Radioactivity in depth

Radioactivity is natural. On earth it comes
from rocks, but it also comes from space
as cosmic rays.
One of the sources of background radiation
is radon gas from uranium in the ground.
The two most common types of radon are
radon-222 and radon-220. concentrations
vary dramatically around the world.
New buildings in high radon areas are
built with vented floors. When
particularly high concentrations exist,
extractor fans are fitted to draw out the
gas before it can pass into the home.
Another way of reducing radon levels is
to use more impenetrable damp proof
membranes on the ground floor.]
Radon-220 has a half life of 55.6 seconds. This
means it is unlikely to be at risk as it decays
before it has a chance to enter buildings. But
radon-222 has a half life of just under 4 days.
This means it has time to enter buildings. There
are a total of 8 decays from radon-222 until a
stable isotope is reached. Half are alpha
emissions and half are beta. The emission of
alpha or beta particles inside the lungs can lead
to lung cancer. Around 5% of the 34,000 uk
deaths each year from Lung cancer are
attributed to radon.
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