Domestic radon remediation of U.K. dwellings by sub-slab depressurisation: evidence for a baseline contribution from constructional materials

Chris J Groves-Kirkby, Anthony R Denman, Paul S Phillips, R Tornberg, Anne C Woolridge, Robin G M Crockett

Research output: Contribution to journalArticleResearchpeer-review

Abstract

To quantify the effectiveness of Sub-Slab Depressurisation, widely used in the United Kingdom (U.K.) to mitigate indoor radon gas levels in residential properties, a study was made of radon concentration data collected from a set of 170 homes situated in Radon Affected Areas in Northamptonshire and neighbouring counties, remediated using conventional sump/pump technology. A high incidence of satisfactory remediation outcomes was achieved, with 100% of the houses remediated demonstrating post-remediation radon concentrations below the U.K. domestic Action Level of 200 Bq m− 3, while more than 75% of the sample exhibited radon mitigation factors (defined as the ratio of radon concentrations following and prior to remediation) < 0.2. Two systematic trends are identified. Firstly, absolute radon concentration reduction following remediation is directly proportional to initial radon concentration, with a mean reduction factor of 0.96 and a residual component of around 75 Bq m− 3. Secondly, houses with lower initial radon concentrations demonstrate poorer (higher) mitigation factors. These observations support a model in which the total indoor radon concentration within a dwelling can be represented by two principal components, one susceptible to mitigation by sub-slab depressurisation, the other remaining essentially unaffected. The first component can be identified with radon emanating from the subsoil and bedrock geologies, percolating through the foundations of the dwelling as a component of the soil-gas, and potentially capable of being attenuated by sub-slab depressurisation or radon-barrier remediation technologies. The second contribution can be identified with radon emanating from materials used in the construction of the dwelling with a further contribution from the natural background level, and is essentially unaffected by ground-level remediation strategies. Modelling of a multi-component radon dependency using ground-radon attenuation factors derived from the experimental data, in conjunction with typical background and structural-radon levels, yields behaviour in good agreement with the observed dependence of mitigation factor on initial radon concentration
Original languageEnglish
JournalEnvironment International
Volume34
Issue number3
DOIs
Publication statusPublished - 1 Apr 2008

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slab
remediation
mitigation
indoor radon
dwelling
material
soil gas
background level
subsoil
bedrock
pump

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Groves-Kirkby, Chris J ; Denman, Anthony R ; Phillips, Paul S ; Tornberg, R ; Woolridge, Anne C ; Crockett, Robin G M. / Domestic radon remediation of U.K. dwellings by sub-slab depressurisation: evidence for a baseline contribution from constructional materials. In: Environment International. 2008 ; Vol. 34, No. 3.
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abstract = "To quantify the effectiveness of Sub-Slab Depressurisation, widely used in the United Kingdom (U.K.) to mitigate indoor radon gas levels in residential properties, a study was made of radon concentration data collected from a set of 170 homes situated in Radon Affected Areas in Northamptonshire and neighbouring counties, remediated using conventional sump/pump technology. A high incidence of satisfactory remediation outcomes was achieved, with 100{\%} of the houses remediated demonstrating post-remediation radon concentrations below the U.K. domestic Action Level of 200 Bq m− 3, while more than 75{\%} of the sample exhibited radon mitigation factors (defined as the ratio of radon concentrations following and prior to remediation) < 0.2. Two systematic trends are identified. Firstly, absolute radon concentration reduction following remediation is directly proportional to initial radon concentration, with a mean reduction factor of 0.96 and a residual component of around 75 Bq m− 3. Secondly, houses with lower initial radon concentrations demonstrate poorer (higher) mitigation factors. These observations support a model in which the total indoor radon concentration within a dwelling can be represented by two principal components, one susceptible to mitigation by sub-slab depressurisation, the other remaining essentially unaffected. The first component can be identified with radon emanating from the subsoil and bedrock geologies, percolating through the foundations of the dwelling as a component of the soil-gas, and potentially capable of being attenuated by sub-slab depressurisation or radon-barrier remediation technologies. The second contribution can be identified with radon emanating from materials used in the construction of the dwelling with a further contribution from the natural background level, and is essentially unaffected by ground-level remediation strategies. Modelling of a multi-component radon dependency using ground-radon attenuation factors derived from the experimental data, in conjunction with typical background and structural-radon levels, yields behaviour in good agreement with the observed dependence of mitigation factor on initial radon concentration",
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Domestic radon remediation of U.K. dwellings by sub-slab depressurisation: evidence for a baseline contribution from constructional materials. / Groves-Kirkby, Chris J; Denman, Anthony R; Phillips, Paul S; Tornberg, R; Woolridge, Anne C; Crockett, Robin G M.

In: Environment International, Vol. 34, No. 3, 01.04.2008.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Domestic radon remediation of U.K. dwellings by sub-slab depressurisation: evidence for a baseline contribution from constructional materials

AU - Groves-Kirkby, Chris J

AU - Denman, Anthony R

AU - Phillips, Paul S

AU - Tornberg, R

AU - Woolridge, Anne C

AU - Crockett, Robin G M

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N2 - To quantify the effectiveness of Sub-Slab Depressurisation, widely used in the United Kingdom (U.K.) to mitigate indoor radon gas levels in residential properties, a study was made of radon concentration data collected from a set of 170 homes situated in Radon Affected Areas in Northamptonshire and neighbouring counties, remediated using conventional sump/pump technology. A high incidence of satisfactory remediation outcomes was achieved, with 100% of the houses remediated demonstrating post-remediation radon concentrations below the U.K. domestic Action Level of 200 Bq m− 3, while more than 75% of the sample exhibited radon mitigation factors (defined as the ratio of radon concentrations following and prior to remediation) < 0.2. Two systematic trends are identified. Firstly, absolute radon concentration reduction following remediation is directly proportional to initial radon concentration, with a mean reduction factor of 0.96 and a residual component of around 75 Bq m− 3. Secondly, houses with lower initial radon concentrations demonstrate poorer (higher) mitigation factors. These observations support a model in which the total indoor radon concentration within a dwelling can be represented by two principal components, one susceptible to mitigation by sub-slab depressurisation, the other remaining essentially unaffected. The first component can be identified with radon emanating from the subsoil and bedrock geologies, percolating through the foundations of the dwelling as a component of the soil-gas, and potentially capable of being attenuated by sub-slab depressurisation or radon-barrier remediation technologies. The second contribution can be identified with radon emanating from materials used in the construction of the dwelling with a further contribution from the natural background level, and is essentially unaffected by ground-level remediation strategies. Modelling of a multi-component radon dependency using ground-radon attenuation factors derived from the experimental data, in conjunction with typical background and structural-radon levels, yields behaviour in good agreement with the observed dependence of mitigation factor on initial radon concentration

AB - To quantify the effectiveness of Sub-Slab Depressurisation, widely used in the United Kingdom (U.K.) to mitigate indoor radon gas levels in residential properties, a study was made of radon concentration data collected from a set of 170 homes situated in Radon Affected Areas in Northamptonshire and neighbouring counties, remediated using conventional sump/pump technology. A high incidence of satisfactory remediation outcomes was achieved, with 100% of the houses remediated demonstrating post-remediation radon concentrations below the U.K. domestic Action Level of 200 Bq m− 3, while more than 75% of the sample exhibited radon mitigation factors (defined as the ratio of radon concentrations following and prior to remediation) < 0.2. Two systematic trends are identified. Firstly, absolute radon concentration reduction following remediation is directly proportional to initial radon concentration, with a mean reduction factor of 0.96 and a residual component of around 75 Bq m− 3. Secondly, houses with lower initial radon concentrations demonstrate poorer (higher) mitigation factors. These observations support a model in which the total indoor radon concentration within a dwelling can be represented by two principal components, one susceptible to mitigation by sub-slab depressurisation, the other remaining essentially unaffected. The first component can be identified with radon emanating from the subsoil and bedrock geologies, percolating through the foundations of the dwelling as a component of the soil-gas, and potentially capable of being attenuated by sub-slab depressurisation or radon-barrier remediation technologies. The second contribution can be identified with radon emanating from materials used in the construction of the dwelling with a further contribution from the natural background level, and is essentially unaffected by ground-level remediation strategies. Modelling of a multi-component radon dependency using ground-radon attenuation factors derived from the experimental data, in conjunction with typical background and structural-radon levels, yields behaviour in good agreement with the observed dependence of mitigation factor on initial radon concentration

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DO - 10.1016/j.envint.2007.09.012

M3 - Article

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JO - Environment International

JF - Environment International

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