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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Mean

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Pre building regs

Post building regs

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