Costs of radon mitigation in Finnish dwellings

This study considers the mitigation methods and costs for dwellings exceeding the indoor radon concentration of 400 Bq/m3. It is based on a 1990-91 radon survey of 3074 randomly chosen dwellings and also takes into account the results of special mitigation and air exchange studies. The number of dwellings exceeding the annual average radon concentration of 400 Bq/m3 was 66 000: 59 000 low-rise residential houses and 7 000 flats. Subslab suction and radon wells prevent radon entry into houses and are the most effective methods. Typical radon reductions for these methods are 80-99% with properly designed installations. Ventilation techniques that reduce indoor radon concentrations were considered adequate if the air exchange rate is less than 0.25 H-1 and the radon concentration less than 600 Bq m-3. The estimated need for mitigation methods in low-rise houses was as follows: 40 000 subslab suction installations, 5 000 radon wells, 4 000 crawl space ventilation repairs, 4 000 basement ventilation repairs and 6 000 other repairs based on ventilation. The total cost of the programme was estimated at 445 million, the average cost for one dwelling is thus FIM 7 500, i.e. USD 1 250 (1 USD=FIM 6). The total cost would be FIM 500 million if the installations in blocs of flats were taken into account. The average annual operating costs were estimated at FIM 270. (orig.). (20 refs., 1 fig., 9 tabs.)