Radon in Nordic countries

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1 Radon in Nordic countries Tarja K. Ikäheimonen Radiation and Nuclear Safety Authority Finland

2 Outline Radon sources Health risk Radon concentrations Reference levels Radon remediation and prevention

3 Radon Radioactive noble gas Odourless, tasteless, invisible Formed from radium, which is a decay product of Uranium ( 238 U) Uranium and radium occur naturally in all soils and rocks, also in building materials Emanates from rocks and soils and tends to concentrate in enclosed spaces like houses Emanation of radon will never reduce nor run out Radon level can only be known by measuring Measurement of radon is easy and inexpensive

4 Radon sources of indoor air Most of the radon emanates from the ground Radon from building materials Usually in minor scale, e.g. in Finland, indoor radon level in apartment houses is on average 40 Bq/m 3 (dwellings in the 2 nd floor or higher) Sweden has problems with radon from building materials (blue concrete) in about dwellings Radon in water from drilled wells Usually in minor scale Transferred from water to indoor air A problem in about dwellings in Sweden, mostly single-family homes In Finland, a problem in households (10% of )

5 Health risk related to radon Radon in homes increases the risk of lung cancer In Nordic countries, the proportion of all lung cancers linked to radon is estimated to 10% (1300 cases / year) Radon is much more likely to cause lung cancer in people who smoke, or have smoked in the past, than in lifelong non-smokers Radon is the second most important cause of lung cancer after smoking in many countries Primary cause of lung cancer among people who have never smoked There is no known threshold concentration below which radon exposure presents no risk Even low concentrations can result in a small increase in risk. The risk increases linearly with concentration and exposure time. WHO Handbook on indoor radon 2009

6 Country Indoor radon concentrations Population (million) Arithmetic mean (Bq/m 3 ) Maximum value (Bq/m 3 ) Denmark Finland Iceland Norway Sweden * Worldwide (population weighted) 39 * Winter measurement without correction. Number of dwellings remediated: - Finland: Sweden: (rough estimate) Percentage over 200 Bq/m 3 (%)

7 Indoor radon maps: Norway and Finland Percentage >200 Bq/m 3 >25 % % 3 10 % 1 3 % <1 % <10 measurements Percentage >200 Bq/m 3 Indoor radon in low-rise residential buildings

8 Resultat av radonmålinger i Tromsø kommune

9 Indoor radon maps: Denmark

10 Reference levels Recommendation for old ones and mandatory for new construction Denmark: reference level of 200 Bq/m 3 for old and new houses Simple remediation measures are recommended when Rn > 100 Bq/m 3 Finland: 400 Bq/m 3 for old and 200 Bq/m 3 for new houses Norway: action level of 100 Bq/m 3, maximum level of 200 Bq/m 3 Mandatory for all schools, day-care centres and rental apartments, 2014 Sweden: same reference level of 200 Bq/m 3 for old and new houses WHO proposes a reference level of 100 Bq/m 3 to minimize health hazards due to indoor radon exposure If this level cannot be reached under the prevailing country-specific conditions, the chosen reference level should not exceed 300 Bq/m 3

11 Radon remediation in existing houses Radon remediation to reduce radon is easy in most cases Remedial measures should aim as low radon concentration as reasonably achievable, preferably below 100 Bq/m 3 Radon remediation should be done with cost-effective and validated methods House characteristics influence the choice of methods Main mitigation methods Sub-slab suction and radon well most effective Improving ventilation in the house, in cellar or in crawl space Sealing entry routes of radon Sub-slab suction

12 Radon prevention in new construction Aim should be to plan and construct so that the radon concentration will be as low as reasonably achievable Average less than 50 Bq/m 3 Base floor should be air tight, including pipe penetrations Crawl space provides low radon levels, if ventilated properly Monolithic concrete slab low radon levels, common in Sweden Sealing of the joint between slab and foundation wall polyester-reinforced bitumen felt (red line) in Finland