1. Large decrease of radon concentrations in new-built Swedish dwellingsby
Tryggve Rönnqvist, Radonova
2018 International Radon Symposium™

2. Large decrease of radon concentrations in new-built Swedish dwellings
Dependencies between building year and radon levels in Swedish dwellings were evaluated:
Data from measurements analyzed during
Dwellings with building years from 1950 until 2016
Dependencies of foundation and ventilation type were investigated
Data were compared against the Swedish reference level of 200 Bq/m3 (5.3 pCi/l)
2018 International Radon Symposium™

3. Large decrease of radon concentrations in new-built Swedish dwellings
Building year
Number of measurements
Average radon conc. (pCi/l)
Highest value (pCi/l)
Above 5.4 pCi/l
(all)
7495
5.0
116
33 %
(blue concrete)
1886
6.8 90
53 %
(no blue concrete)
2519
4.4
110
27 %
8099
2.4
123
11 %
2332
1.7 52
6.1 %
2255
1.1
165
2.0 %
Measurements in single-family houses
2018 International Radon Symposium™

4. Large decrease of radon concentrations in new-built Swedish dwellings
Building year
Number of measurements
Average radon conc. (pCi/l)
Highest value (pCi/l)
Above 5.4 pCi/l
(all)
10080
3.4
124
20 %
(blue concrete)
2824
5.2 48
38 %
(no blue concrete)
1568
2.5
10 %
8691
1.4 56
5.1 %
3170
1.3 38
3.9 %
3942
0.8 41
0.3 %
Measurements in apartments in multi-family houses
2018 International Radon Symposium™

5. Large decrease of radon concentrations in new-built Swedish dwellings
Single-family houses = ”Småhus”
Multi-family houses =
”Flerbostadshus”
Number of new-built dwellings in Sweden (source: SCB)
2018 International Radon Symposium™

6. Large decrease of radon concentrations in new-built Swedish dwellings
Measurement year
Number of measurements
Average radon conc. (pCi/l)
Highest value (pCi/l)
Above 5.4 pCi/l
988
1.9
136
6.6 %
967
106
5.7 %
551
2.1 43
8.5 %
240
2.3 46
10.4 %
227
1.8 18
9.7 %
154
2.0 52
6.5 %
New buildings: are radon levels increasing with time?
Measurements in single-family houses built
No statistical significant change can be seen, Kruskal-Wallis test (p-value = )
2018 International Radon Symposium™

7. Large decrease of radon concentrations in new-built Swedish dwellings
Crawl space
Basement
Split level
Slab on grade
Radon levels and foundation types in single-family and multi-family houses
2018 International Radon Symposium™

8. Large decrease of radon concentrations in new-built Swedish dwellings
Today, most Swedish single-family houses are built with Slab on grade as foundation type and very few new houses have Basements.
2018 International Radon Symposium™

9. Large decrease of radon concentrations in new-built Swedish dwellings
Slab on grade together with Basement are the dominating foundation types in multi-family houses
2018 International Radon Symposium™

10. Large decrease of radon concentrations in new-built Swedish dwellings
Multi-family houses
Single-family houses
New single-family houses with mechanical or balanced mechanical ventilation have in average much lower radon concentrations than houses with only natural ventilation.
Radon levels and ventilation types
2018 International Radon Symposium™

11. Large decrease of radon concentrations in new-built Swedish dwellings
Today, very few single-family houses have only natural ventilation, mechanical or balanced mechanical ventilation are dominating.
2018 International Radon Symposium™

12. Large decrease of radon concentrations in new-built Swedish dwellings
Today, most new multi-family houses have balanced mechanical ventilation.
2018 International Radon Symposium™

13. Large decrease of radon concentrations in new-built Swedish dwellings
Possible explanations for the decreased radon concentrations in new-built Swedish dwellings :
Better and more uniform building practice.
Mechanical or balanced mechanical ventilation are used in almost all new Swedish dwellings.
Very few new single-family houses are built with basement, the dominating foundation type is slab on grade.
2018 International Radon Symposium™

14. Tryggve Rönnqvist +46 706591708 tryggve.ronnqvist@radonova.com
THANK YOU !!
Tryggve Rönnqvist
2018 International Radon Symposium™