Alan,
Below are some notes I made at a districts meeting Oct 2009, hope they are of use to you.


Radon was also highlighted at the meeting as an issue to the general workforce especially in the midlands as indicated in attached map.

Radon - England and Wales
This map (go to web site) is taken from the Indicative Atlas of Radon in England and Wales (HPA-RPD-033).
The estimated radon potential for an individual home can be obtained through a website, www.UKradon.org [outside link].
Radon is a natural occurring radioactive gas. You cannot see, hear, feel or taste it. It comes from the minute amounts of uranium that occur naturally in all rocks and soils. Radon is present in all parts of the UK, although the gas disperses outdoors so levels are generally very low. We all breathe it in throughout our lives - for most UK residents, radon accounts for half of their total annual radiation dosage. However, geological conditions in certain areas can lead to higher than average levels. This can be found where natural ground levels have been noticeably altered as per the rear car park. Some of the highest radon levels have been found in the southwest, but levels well above average have been found in some other parts of the UK. Exposure to particularly high levels of radon may increase the risk of developing lung cancer.
The HPA has advised that indoor radon above an Action Level of 200 Becquerel’s per cubic metre should be reduced. Most homes in the UK have fairly low radon levels, with an average of about 20 Becquerel’s per cubic metre. The HPA conducts radon surveys for government departments, local councils, other organizations, and private householders.
Small radon detectors can be sent directly to householders/ companies by post, and returned at the end of a three month period. Radon causes invisible damage to the plastic inside the detector. This damage can be measured and used to calculate the radon level. The householder is sent the result by letter.
The HPA has advised that indoor radon above an Action Level of 200 Becquerel's per cubic metre should be reduced. Most homes in the UK have fairly low radon levels, with an average of about 20 Becquerel’s per cubic metre. The HPA conducts radon surveys for government departments, local councils, manufacturing organizations, and private householders.
Small radon detectors can be sent directly to householders by post, and returned at the end of a three month period. Radon causes invisible damage to the plastic inside the detector. This damage can be measured and used to calculate the radon level. The householder is sent the result by letter.
The only reliable guide to the level of radon in a building is a measurement over a period long enough to average out short-term variations in radon levels - this should ideally be three months. The procedure recommended by the HPA is to use passive monitors as they are reliable, simple to use and can be sent by post. The individual result for each site is confidential and will not be given to anyone else without the prior consent of the site holder at the time of the measurement. This service is available to any site holder in the UK. This includes the supply of two radon detectors, their subsequent analysis and the reporting of the result. All packaging and return postage are also included.
A radon detector with improved performance has been introduced by the HPA, replacing the previous yellow detector. The replacement monitor is black because the outer shell is made of carbon-loaded plastic which reduces uncertainties caused by the build-up of electrostatic charge. The detector increases the efficiency and reliability of the measurement service.
Radon screening
There may sometimes be a need for rapid information about radon, for example to test the effect of mitigation work or when planning structural changes to a building. In such cases, screening tests can be helpful provided they are conducted in addition to the standard three-month test. This service provides an early indication of the likely result after only a couple of weeks. As with all short-term measurements, the result will be inconclusive in some cases. In such cases, the second set of detectors, returned after three months, will provide further information and a numerical value. The result is expressed in units that are directly comparable with the Action Level.

Result of screening measurement Conclusion, in relation to the Action Level Value provided
Less than 100 Bq m-3 Unlikely the AL is exceeded. Yes
Between 100 Bq m-3 and 400 Bq m-3 Uncertain, need longer test. No
More than 400 Bq m-3 Likely the AL is exceeded. Yes

A radon detector pack can be ordered from the www.UKradon.org website for approximately £65.00. The effect of ventilation, in principle, radon may be prevented from accumulating in premises with particularly high influx of fresh air, but a measurement is still required unless a risk assessment can show that the radon level at a particular location is necessarily low at all times when it is occupied. Furthermore there will often be adjoining or linked places, such as an office, store, computer area or access duct, with quite different conditions where a measurement would be required.


Badger