Data from local authority radon measurement programmes ...Data from local authority radon...
Transcript of Data from local authority radon measurement programmes ...Data from local authority radon...
Data from local authority radon measurement programmes – observations on the effectiveness
of radon prevention in Ireland
Alison Dowdall
What am I going to talk about?
Background on local authority measurement programmes
Summarise the local authority data
Look at the effectiveness of building regulations using local authority data
Radon and Cork County Council
High radon levels found in homes and workplaces in north Cork
Over 4,500 homes measured by Cork co.co
6.5% above 200 Bq/m3
Highest measurement 3,300 Bq/m3
All homes have been remediated
RPII guidance for local authorities
Produced in consultation with Cork county council
Covers all aspects of a radon measurement programme
Issued to all local authorities and on www.rpii.ie
Predictive map of radon in Irish dwellings
National Radon Survey
For each 10 km grid square the percentage of houses above 200 Bq/m3 is predicted.
Squares with > 10% are designated High Radon Areas (HRA)
Estimated 7% of homes in Ireland have radon levels above 200 Bq/m3
1997 Building Regulations
All new buildings -potential means of extracting radon from the substructure such as a standby radon sump
In addition, in HRAs -fully sealed membrane of low permeability over the entire footprint of the building
Summary of local authority results to date
Measurement and remediation programmes rolled out successfully
Approx. 20,000 social homes tested in 37 local authorities and town councils
1144 (6%) homes above 200 Bq/m3
93 of which were above 800 Bq/m3
Maximum level found was 4542 Bq/m3
Remediation of local authority homes Most homes remediated successfully
Mainly by a fan assisted sump
Cork - mean reduction of 92%
One local authority used passive sumps in 8 homes
- Radon concs. between 220 – 284 Bq/m3
- Successfully reduced to 12 – 110 Bq/m3
What can we learn from the local authority data?
Look at the effectiveness of the radon barrier in local authority homes
Data from HRAs
Pre and post building regulations
Minimum of 5 measurements to compare
Local authority data matching these criteria
County No. of grid squares
No. of homes pre 1998
No. of homes post 1998
Clare 4 155 184
Cork 7 183 136
Sligo 1 178 140
Waterford 5 113 174
Wicklow 6 138 293
Total 23 758 918
Location of grid squares analysed
Building regulations – effectiveness?
Reduction in mean radon concentration:
- Mean concentration in pre-98 homes 134 Bq/m3
- Mean concentration in post-98 homes 88 Bq/m3
- 34% reduction in mean concentration
- Reduction ranges from 0-76%
Reduction in no. of homes >200 Bq/m3
- 9% of pre-98 homes >200 Bq/m3
- 4.5% of post-98 homes >200 Bq/m3
- Max conc. pre-98 2133 Bq/m3 vs post-98 864 Bq/m3
Previous studies on effectiveness of the radon barrier
Studies of private homes in Ennis, Tralee and Kilkenny and more recently, larger study of local authority data in Co. Cork
Effectiveness of the barrier about 50% (ranging from 0% to 70%)
International studies - effectiveness ranges from 0% to 90%
Reduction in the no. of homes > 200 Bq/m3 ≈ 50%
Comparison of pre-98 and post-98 analysis by grid square 15 grid squares (65%) - reduction in mean
radon concentration post-98
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Comparison of pre-98 and post-98 analysis by grid square
Pre-98 mean radon conc. above ≈ 70 Bq m-3 a reduction is seen
Pre-98 below ≈ 70 Bq m-3 reduction more difficult to demonstrate
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70 Bq/m3
Requirement for barrier and mean radon concentration
Current requirement for barrier in HRA
In NRS, mean radon conc. in all HRA grid squares >70 Bq m-3
Mean radon conc. in 31% of grid squares (not HRA) >70 Bq m-3
NRS estimated 3% of all homes in grid squares (not HRA)> 200 Bq m-3
Use of mean radon concentration in future radon prevention policy?
Conclusions
Effectiveness of the barrier found to be 34% (ranging from 0% to 76%)
Reduction in no. of homes exceeding the reference level and in max. concentration measured
Emergence of a mean radon concentration below which barrier effectiveness is difficult to demonstrate
Consider using mean radon concentration in future radon prevention policy?
Acknowledgements
Acknowledge the radon measurement programmes by local authorities in particular Clare, Cork, Waterford and Wicklow County Councils and Sligo Borough Council
Thank them for the invaluable dataset
Local authority programmes of testing and remediation of social housing should be continued
Thank you for your attention