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What is radon?

Radon-222, commonly called radon, is a naturally occurring inert,radioactive gas. It is colourless, odourless and tasteless and can

be detected only using specialist equipment. Radon is producedfrom uranium, which is present in small quantities in all rocks andsoils. As it is a gas, radon can move easily through the soilenabling it to enter the atmosphere or seep into buildings. Whenradon enters the atmosphere it is quickly diluted to harmlessconcentrations, but when it enters a building it can sometimesaccumulate to unacceptably high and unsafe concentrations.

What are the risks from radon?

Radon is classified as a Class A carcinogen by the InternationalAgency for Research on Cancer, a part of the World HealthOrganisation. Being a Class A carcinogen means that radon hasbeen shown to be a cause of cancer on the basis of humanepidemiological studies.

The risks from exposure to radon depend on the time for whichone is exposed and the concentrations to which one is exposed.While smoking is the primary cause of lung cancer worldwide, therisk of contracting lung cancer due to radon exposure issignificant. Radon is linked to 10-15% of the approximately 1500lung cancers deaths in Ireland each year. A synergisticrelationship, greater than additive and less than multiplicative,exists between radon exposure and smoking.

Detection of Radon

Radon concentration, which is measured in units of becquerels percubic metre (Bq/m3), can be determined by placing one or morepassive radon detectors in an area for three months. The

detectors are unobtrusive, being about 6 cm in diameter, and canbe placed on a desk or shelf or affixed to a wall.

In homes, twodetectors are placedin the house for athree-month period.One detector isplaced in the livingarea and the otherin a bedroom. Theradon concentrationis determined usingthe average of these

two measurements.

For workplaces, one detector per office or classroom is sufficient.In open-plan workplaces, one detector per 200 m2 of floor-space isconsidered adequate to properly measure the radonconcentrations present. A radon measurement service forworkplaces is available from a number of companies on acommercial basis.

Indoor Radon in Ireland

Radon in Homes: Between 1992 and 1999 the RadiologicalProtection Institute of Ireland (RPII) conducted a comprehensivesurvey the National Radon Survey - of radon in homes in Ireland.This survey was carried out to identify areas most at risk fromindoor radon. The survey enabled the designation of High RadonAreas, defined as those areas where it is predicted that 10% ormore of houses will have radon concentrations greater than theReference Level of 200 Bq/m3. High Radon Areas have been foundin every county in Ireland though they are predominantly found in

the west and southeast. The average indoor radon concentrationin Irish homes is 89 Bq/m3 while, nationally, approximately 7% ofall homes are estimated as having radon concentrations greater

than 200 Bq/m3. The RPII encourages all householders,particularly those in High Radon Areas, to measure radonconcentrations in their homes.

Radon in Workplaces: In 1996, the European Council Directive96/29 Euratom required Member States to implement legislationto control exposure to natural sources of radioactivity, includingradon, in the workplace. This Directive was enacted into Irishlegislation by the Radiological Protection Act, 1991 (IonisingRadiation) Order, 2000, Statutory Instrument No. 125 of 2000 (S.I.125 of 2000). S.I. No. 125 sets a Reference Level for workplacesof 400 Bq/m3 averaged over any three-month period. This ishigher than the Reference Level for homes because of loweroccupancy rates in workplaces. If workplaces have concentrationsabove this specified value employers must evaluate whetherremedial action to reduce the radon concentration to less than400 Bq/m3 is justified. S.I. No. 125 of 2000 also empowers the RPIIto direct employers to have radon measurements carried out intheir workplace.

The Safety, Health and Welfare at Work Act, 1989, requiresemployers to identify the hazards in the workplace, assess the riskto health and safety from these hazards and put in place measuresto eliminate or reduce the risk. The Health and Safety Authorityinterprets the identification of workplace hazards from radon tomean that all indoor workplaces in High Radon Areas must haveradon measurements carried out.

Radon in Schools: In 1998 the Department of Education andScience (DES) commissioned the RPII to carry out a survey of radonconcentrations in all schools in the country. To date 85% of schoolsin the voluntary, community and comprehensive sectors have beentested for radon. Of these, 898 schools have one or more groundfloor rooms with radon concentrations above 200 Bq/m3. Aprogramme to remediate all affected schools was initiated by DESand is nearing completion. All remediated schools are tested bythe Institute to ensure that the remedial systems are workingsatisfactorily. A full report on the Radon in Schools survey is beingprepared for publication by the RPII.

The Institute is currently working with the DES to encourage thesome 600 schools that did not participate in the initial survey to

now measure radon. It is planned to issue radon detectors tothese schools in January 2004.

Conclusions

There is direct evidence of a link between exposure to high levelsof radon and an increased risk of lung cancer. Measurement ofradon is straightforward, relatively inexpensive and in everyonesinterest to carry out both in homes and workplaces. A radonmeasurement is the only way of checking if indoor radonconcentrations are below the Reference Level. Results showinglow concentrations provide reassurance to the building occupants.Where high concentrations are present, remediation is normallyeffective and easy to implement and a number of specialistremediation companies are already operating in Ireland.

Further information on radon, as well as maps showing thelocation of High Radon Areas, can be obtained from the RPII

website at www.rpii.ie

P H Y S I C A L S C I E N C E S M A G A Z I N E

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Radon Gas in Ireland

David Fenton, Radiological Protection Institute of Ireland