Predictability of radon airborne measurements based on surrogate measures

222 Pages·2015·5.07 MB·English

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