Radon

Question 1

Radon 222 is

Answer 1

a radioactive ( particles) gas which comes from uranium and occurs 
naturally in many rocks and soils. Radon can seep out of the ground and build up in 
houses and indoor workplaces.

Question 2

The health effects of radon

Answer 2

Breathing in radon is the second largest
cause of lung cancer in the UK (after
smoking). It accounts for 3-5% of all lung
cancers in the UK and around 2000 fatal
cancers per year. The risk from radon is
approximately 25 times higher for cigarette
smokers than for non-smokers.

Most radon gas breathed in is immediately
exhaled and presents little radiological
hazard. However, the decay products of
radon (radon daughters) behave more like
solid materials than a gas and are
themselves radioactive.

These solid decay products attach to atmospheric dust and water droplets which can
then be breathed in and become lodged in the lungs and airways. Some decay
products emit alpha particles which cause significant damage to the sensitive cells in
the lung.

Question 3

Radon is present in all buildings: the

average level in the UK is

Answer 3

20 becquerels 
per cubic metre of air. Some workplaces 
have  been  found  to  have  measured 
radon  levels  significantly  in  excess  of 
the 400 Bq/m
3
 action level. Worst cases 
have shown levels over 17,000 Bq/m
3
.

Question 4

Practical control of radon levels in buildings

Answer 4

New buildings can be protected
during construction by installing a
‘radon proof barrier/ membrane’
within the floor structure.

In existing buildings the best
approach is to prevent radon entering
the building by altering the balance of
pressure between the room and the
ground. Pressure inside the building
can be increased by blowing air from
the roof space with a small fan and
pressure under the floor is reduced
by connecting a low power fan to a
small sump and extracting the air.

Question 5

It is good practice to set a timescale after which re-measurement of the radon levels
will occur. The HSE suggests the following guidelines: 3

Answer 5

 where initial levels were significantly less than 400 Bq/m
3
re-measurement should
occur once every 10 years
 where initial levels were just below 400 Bq/m
3
re-measurement should occur
before 10 years
 where initial levels were above 400 Bq/m
3
and measures have been taken to
reduce radon exposures (such as engineered systems or occupancy restrictions),
the re-measurement periods may need to be significantly more frequent in order
to verify their continuing effectiveness.