IGEM in association with the National Radiological
Protection Board (NRPB) has produced this information to answer
some of the questions which you may have on the issue.
Introduction
Radon is a colourless, odourless gas with radioactive
properties. In the UK many people are aware that radon is present
in their homes. This radon arises naturally from the soil and rock
in the ground. The National Radiological Protection Board (NRPB) is
advisor to the government on radiation protection and provides a
service for householders to assess the level of radiation present
in their homes.
Very low levels of radon are also present in natural gas. The
radon enters the gas from the rock formations which surround the
gas reservoir.
The NRPB has carried out an assessment of the health impacts
from radon in UK natural gas and confirmed that they present a
negligible risk to health.
The Institution of Gas Engineers and Managers in association
with the NRPB has produced this information to answer some of the
questions which you may have on the issue.
Sources of Radioactivity
Wherever we are, whatever we do, we are surrounded by radiation,
which comes from many different sources, some natural, some
artificial.
The amount of radiation which a person receives is called the
dose. The average annual dose to the UK population is 2,600 units
from all sources.
Anyone who receives additional exposure to a particular source
of radiation will increase their annual dose. For example,
shellfish accumulate radioactive materials that are naturally
present in water, so that people who regularly consume large
quantities of mussles, cockles or winkles can receive a total dose
of radiation which is one fifth more than the average UK
resident.
In the same way, some jobs involve additional exposure to
natural sources of radiation. For example, airline pilots are
exposed to higher than average levels of radiation from cosmic
rays.
Units
One dose unit is called a microsievert.
A microsievert is one millionth of a sievert.
A sievert is an international unit which is used to express the
effective dose of radiation received.
Average Person in the UK
Annual dose 2,600 units from all sources.
Natural Sources
- 50% radon gas from the ground
- 14% gamma rays from the ground & buildings
- 11.5 food and drink
- 10% cosmic rays
Artificial Sources
- 14% Medical
- <0.1 nuclear discharges
- <0.1 consumer products
- <0.2 fallout
- <0.3 occupational
What is Radon?
Radon is a colourless gas with no smell. It originates from the
decay of minute quantities of naturally occuring uranium in the
rocks beneath us. The radon moves up through the soil or along
cracks in the rock until it reaches the surface. Once there, it
disperses into the atmosphere and becomes another part of our
background radiation.
Where does radon in natural gas come from?
Just as radon is present in the soil and rock of the UK mainland
it is also present in the rock from which coal, oil and natural gas
are extracted. This means that traces can be found in supplies of
coal, oil and natural gas.
How high are the levels of radon in natural gas?
The levels of radon in sources of UK natural gas have been
monitored since the 1970s and are very low.
The NRPB has shown that the radon in natural gas presents no
significant health risk to gas consumers.
The extra radiation which an average gas customer receives from
cooking and central heating over a whole year is less that half the
amount of radiation received during a plane flight to Spain.
Do other countries have radon in their natural gas?
The presence of radon in natural gas has been known for a long
time worldwide - since the early 1900s. According to an expert
committee of the United Nations, the levels found in the natural
gas extracted from the North Sea are much lower than those found in
gas supplies in other parts of the world.
How does this affect you?
To put things into perspective:
- Over a year the average person in the UK is exposed to 2,600
units in their everyday life.
- The extra yearly dose received by a domestic customer using gas
for cooking and central heating is 4 units. That is 650 times lower
than the dose from everyday activities.
The following diagram allows a comparision of those doses
received from various sources of radiation - both natural and
artificial.
20,000 maximum additional dose recommended
2,600 average dose from natural radiation in the UK
1,000 maximum additional dose recommended for a member of the
public
500 average dose from being a heavy consumer of seafood
70 approximate additional dose during a 15 hour flight, e.g. a
return flight from London to North America
20 dose from a single chest x-ray
10 approximate additional dose during a two hour flight e.g. to
Spain
4 Average annual dose to a domestic customer using natural gas
for cooking and central heating
0.0001 estimated annual dose to a member of the public from a
gas-fired power station (living in the vicinity of the station)
*maximum additional dose recommended in 1990 by the
International Commission on Radiological Protection.
Why have you not heard about this before?
The levels present in the UK have not required any special
precautions to be taken by gas customers and so additional
information about this subject was not produced.
There has been a recent change in European Legislation covering
sources of radiation. The European Union is harmonising its
legislation with international standards. It is in response to the
interest generated by these changes that this information is being
provided.
Do you need to do anything?
There is no significant risk to your health from radon in
natural gas. The levels of radon in gas are so low that there is no
need to take any special precautions.
There are regular checks in place by the NRPB and the gas
industry to ensure that the levels of radon in natural gas supplied
to you remain very low.
Further Information
If you wish to know more about this subject or have any concerns
please contact:
The National Radiological Protection Board
Chilton
Didcot
Oxon
OX11 0RQ
Tel: +44(0)1235 831600
Fax: +44(0)1235 833891
www.hpa.org.uk/radiation
The Institution of Gas Engineers and Managers
IGEM House
26-28 High Street
Kegworth
Derbyshire
DE74 2DA
Tel: +44(0)844 375 4436
fax: +44(0)1509 678198
