e-Services and the Built Environment: Radon Gas

Radon gas occurs naturaly by the radioactive dacay of Uranuim, which is present in small quantities underneath houses and in some building materials. The gas, like Carbon Monoxide, is colourless, odourless and tasteless but has been identified as the second largest cause of lung cancer after smoking. Radon levels vary widely in the UK, but the gas is particularly prevalent in areas of granite or limestone. Epecially where these rocks make up the building materials, for example, in “the Granite City” of Aberdeen.
Concentrations in the open air are very low. Radon in soil and rocks mixes with air and rises to the surface where it is quickly diluted in the atmosphere. However, Radon that enters enclosed spaces and buildings, can reach relatively high concentrations in some circumstances, especially in buildings with insufficient ventilation.

Health Effects of Radon Inhalation.

Breathing high concentrations of radon can cause lung cancer. The risk is neverless small because the gas is radiologically not very active, with a half-life of 4 days. Unfortunately, the decay products of radon itself are more hazardous isotopes of solid elements with an active 30 minute half-life. These particles, such as Polonium, irradiate the lungs more effecitvely upon inhalation and can be especially dangerous since they can attach to other natural aerosols and subsequently become lodged in the lining of the respiratory system. It is therefore important to reduce indoor radon concentrations as low as reasonably practicable.
In addition, smoking and exposure to radon are known to work together to greatly increase the risk of developing lung cancer. Smokers may be several times more likely to contract lung cancer from a lifetime radon exposure at 200Bqm-3 than the general population (SOURCE: the 6th Committee of the Biological Effects of Ionizing Radiation of the American National Academy of Science)
It is believed that environmental radon accounts for between 2000 and 3,300 lung cancer deaths in the UK annually, which is 3 - 5% of the total lung cancer deaths.

Radon Detection.

Radon levels in homes vary on both a dayly and yearly basis. This is mainly because of temperature differences between indoors and outdoors. Concentrations of Radon are generally higher at night and during the winter. Even in a home with good draught proofing and double-glazing, the air changes several times a day. Increasing the ventilation, especially on the ground floor, will in most cases cause a moderate reduction in the radon level.
There are four main categories of detectors: -

Etched-track detectors - The most popular and cost effective detector. Alpha particles leave tracks in a plastic over a three-month period. The detectors are sent to labs, processed to reveal the pitting made by alpha particles. The pits are microscopically counted permitting a radon level to be computed.

Electret detectors - These can be used for measurements over periods from days to months; operates by gauging the loss of electrostatic charge which is neutralised by alpha particles emitted by radon and its decay products over the period, from which radon concentration can be calculated. These detectors are extremely delicate and must be handled carefully for accurate results.

Charcoal detectors - Not suitable for long-term measurement; least accurate and used when a rapid measure is required. Activated charcoal absorbs radon, and the laboratory can determine a rough estimate of radon concentration.

Active monitors - The most effective and expensive Radon detector. Provides an electronic continuous measure of radon or its decay products; permits figures to be obtained over consecutive hours.