ENG GEO

RADON


General Information:


Radon is a natural radioactive noble gas that is colorless, odorless and tasteless. It is a product of the radioactive decay of uranium that is present in soil and rocks. Every year people receive a certain dose of radiation and a share of radon represents 55% of the total. Radon can escape relatively easily from soil and rocks and accumulate in buildings. When radon gas is inhaled, densely ionizing alpha particles emitted by deposited short-lived decay products of radon can interact with biological tissue in lungs and can ultimately lead to lung cancer. According to the World Health Organization radon is classified as a carcinogenic substance. Studies also showed that radon and its decay products are the second leading cause of lung cancer after smoking.

Indoor Radon Concentrations:

There are several factors affecting radon indoor concentrations, such as air exchange, state of the building and geological characteristics of the area. Natural ventilation has always been considered as a way of reducing radon levels in houses. Ventilation reduces the radon concentration through dilution. Another fundamental factor affecting indoor radon concentration is a permeability of the building to soil gas. Proper diagnosis of radon entry routes and an understanding of building construction are important for effective control of radon. Measuring radon levels, reviewing building construction plans and checking building tightness, conducting investigation to determine possible radon entry routes are the steps typically taken when conducting diagnosis. There have been studies of soil gas measurements for indicating potential indoor radon concentrations. However, no strong correlation has been found between the overall radon concentration in soil gas and inside the home.

Measurement Techniques:

Long term radon measurements are more often carried out using passive devices ,such as alpha track detectors also known as nuclear track detectors, or etched track detectors, or solid state nuclear track detectors. The most commonly used materials in passive radon detectors are plastics known as CR-39 and LR-115. The closed detector excludes radon decay products and records only those alpha particles generated by the radon entering the device container. Alpha particles cause damages to the sensitive plastic that become optic visible as tracks after chemical processing of the plastic and therefore can be used for determining radon levels.  

For more information on radon please follow the links below:

http://www.who.int/ionizing_radiation/env/radon/en/
http://www-ns.iaea.org/tech-areas/radiation-safety/public-radiation-protection.asp?s=3