Predictability of radon airborne measurements based on surrogate measures PDF
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University of Iowa Iowa Research Online Theses and Dissertations 2012 Predictability of radon airborne measurements based on surrogate measures Nirmalla Barros University of Iowa Copyright 2012 Nirmalla G. Barros This dissertation is available at Iowa Research Online: http://ir.uiowa.edu/etd/4570 Recommended Citation Barros, Nirmalla. "Predictability of radon airborne measurements based on surrogate measures." PhD (Doctor of Philosophy) thesis, University of Iowa, 2012. http://ir.uiowa.edu/etd/4570. Follow this and additional works at:http://ir.uiowa.edu/etd Part of theOccupational Health and Industrial Hygiene Commons PREDICTABILITY OF RADON AIRBORNE MEASUREMENTS BASED ON SURROGATE MEASURES by Nirmalla Barros An Abstract Of a thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Occupational and Environmental Health in the Graduate College of The University of Iowa May 2012 Thesis Supervisor: Professor R. William Field 1 ABSTRACT This research focuses on the evaluation of temporal and spatial variability associated with radon airborne measurements and the predictive utility of surrogate measures to estimate radon concentrations within the same environment as well as in other environments. This dissertation consists of three components. In Chapter II, “Evaluation of agreement of time-integrated basement residential radon measurements and correctness of further radon testing indicators”, we investigated the temporal variability between short-term and annual residential radon measurements collected on the lowest livable level and identified housing/occupant factors that influenced each measurement as well as their differences. The false negative rate of how often the short-term test incorrectly indicated that further radon testing was unnecessary was 12 percent at the action level of 148 Bq m-3, but dropped to two percent at a 74 Bq m-3 reference level. The foundation wall material of the basement was the only significant factor to have an impact on the absolute difference between both measurements. This study has the potential to significantly influence public health policy concerning radon testing protocols, specifically the need to re-assess the EPA’s current radon mitigation guidance level of 148 Bq m-3. In Chapter III, “Temporal and spatial variation associated with residential airborne radon measurements”, we investigated the temporal and spatial variability between basement winter short-term and annual radon measurements performed in upper floors of the home and identified housing/occupant factors that influenced each measurement as well as their differences. This study found that individuals would be falsely overestimating their potential exposure to radon half the time at the EPA’s action level of 148 Bq m-3 based on basement short-term tests and much more frequently (80 percent of the time) at a lower reference level of 74 Bq m-3. The 2 presence of a sump was the only factor that was significantly associated with the absolute difference between both these measurements. This study has the potential to influence public health policy in regard to exposure surrogate measures, specifically to encourage testing of radon in living areas of the home and not relying solely on a screening measurement to estimate the concentration of radon in the entire home. In Chapter IV, “Comparative survey of outdoor, residential, and workplace radon concentrations”, we investigated occupational radon concentrations in above ground workplaces in Missouri and compared them to above ground radon concentrations in nearby homes and outdoor locations and evaluated the utility of above ground annual home and outdoor concentrations to predict above ground radon concentrations at a nearby workplace. Employees at county agencies, schools, and businesses were recruited to participate in the study. Annual above ground workplace radon concentrations were found to be similar to annual radon concentrations in the upper floor of homes. Annual non-basement first floor home and outdoor radon concentrations were poor predictors of annual above ground radon concentrations at a nearby workplace. This study provides insights into the potential for above-ground radon exposures in the workplace and the potential agreement between workplace and residential radon concentrations. Abstract Approved: ____________________________________ Thesis Supervisor ____________________________________ Title and Department ____________________________________ Date PREDICTABILITY OF RADON AIRBORNE MEASUREMENTS BASED ON SURROGATE MEASURES by Nirmalla Barros A thesis submitted in partial fulfillment of the requirements for the Doctor of Philosophy degree in Occupational and Environmental Health in the Graduate College of The University of Iowa May 2012 Thesis Supervisor: Professor R. William Field Copyright by NIRMALLA BARROS 2012 All Rights Reserved Graduate College The University of Iowa Iowa City, Iowa CERTIFICATE OF APPROVAL _______________________ PH.D. THESIS _______________ This is to certify that the Ph.D. thesis of Nirmalla Barros has been approved by the Examining Committee for the thesis requirement for the Doctor of Philosophy degree in Occupational and Environmental Health at the May 2012 graduation. Thesis Committee: ___________________________________ R. William Field, Thesis Supervisor ___________________________________ Renee Anthony ___________________________________ David Osterberg ___________________________________ Mary Kathryn Cowles ___________________________________ Lucie Laurian ___________________________________ Daniel Steck ACKNOWLEDGMENTS I am grateful to many people who supported me to complete this project. Thank you to my committee members for their collaboration and guidance. I am also appreciative of assistance from Dan Olson of the Iowa Cancer Registry, Dan Field, Phil Jalbert, Paul Kotrappa, Mark Salasky, and Michael Kitto. I am grateful notably to Paul Skinner for his endless assistance with geocoding and numerous other aspects of this project. I am especially thankful to my advisor, Dr. Bill Field, for his expert advice, inspiration, and exceptional support. Finally, I am grateful to my family for their constant encouragement and endless reassurance. ii ABSTRACT This research focuses on the evaluation of temporal and spatial variability associated with radon airborne measurements and the predictive utility of surrogate measures to estimate radon concentrations within the same environment as well as in other environments. This dissertation consists of three components. In Chapter II, “Evaluation of agreement of time-integrated basement residential radon measurements and correctness of further radon testing indicators”, we investigated the temporal variability between short-term and annual residential radon measurements collected on the lowest livable level and identified housing/occupant factors that influenced each measurement as well as their differences. The false negative rate of how often the short-term test incorrectly indicated that further radon testing was unnecessary was 12 percent at the action level of 148 Bq m-3, but dropped to two percent at a 74 Bq m-3 reference level. The foundation wall material of the basement was the only significant factor to have an impact on the absolute difference between both measurements. This study has the potential to significantly influence public health policy concerning radon testing protocols, specifically the need to re-assess the EPA’s current radon mitigation guidance level of 148 Bq m-3. In Chapter III, “Temporal and spatial variation associated with residential airborne radon measurements”, we investigated the temporal and spatial variability between basement winter short-term and annual radon measurements performed in upper floors of the home and identified housing/occupant factors that influenced each measurement as well as their differences. This study found that individuals would be falsely overestimating their potential exposure to radon half the time at the EPA’s action level of 148 Bq m-3 based on basement short-term tests and much more frequently (80 percent of the time) at a lower reference level of 74 Bq m-3. The iii presence of a sump was the only factor that was significantly associated with the absolute difference between both these measurements. This study has the potential to influence public health policy in regard to exposure surrogate measures, specifically to encourage testing of radon in living areas of the home and not relying solely on a screening measurement to estimate the concentration of radon in the entire home. In Chapter IV, “Comparative survey of outdoor, residential, and workplace radon concentrations”, we investigated occupational radon concentrations in above ground workplaces in Missouri and compared them to above ground radon concentrations in nearby homes and outdoor locations and evaluated the utility of above ground annual home and outdoor concentrations to predict above ground radon concentrations at a nearby workplace. Employees at county agencies, schools, and businesses were recruited to participate in the study. Annual above ground workplace radon concentrations were found to be similar to annual radon concentrations in the upper floor of homes. Annual non-basement first floor home and outdoor radon concentrations were poor predictors of annual above ground radon concentrations at a nearby workplace. This study provides insights into the potential for above-ground radon exposures in the workplace and the potential agreement between workplace and residential radon concentrations. iv
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