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Article

Contextualizing Radon Mitigation into Healthy and Sustainable Home Design in the Commonwealth of Kentucky: A Conjoint Analysis

by
Osama E. Mansour
1,2,*,
Lydia (Niang) Cing
1 and
Omar Mansour
3
1
School of Engineering and Applied Sciences, Western Kentucky University, Bowling Green, KY 42101, USA
2
School of Architecture Planning and Landscape, University of Calgary, Calgary, AB T2N 1N4, Canada
3
Department of Mechanical Engineering, Columbia University, New York, NY 10027, USA
*
Author to whom correspondence should be addressed.
Sustainability 2025, 17(14), 6543; https://doi.org/10.3390/su17146543
Submission received: 2 June 2025 / Revised: 4 July 2025 / Accepted: 12 July 2025 / Published: 17 July 2025
(This article belongs to the Section Pollution Prevention, Mitigation and Sustainability)
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Abstract

Indoor radon constitutes a public health issue in various regions across the United States as the second leading cause of lung cancer following tobacco smoke. The U.S. Environmental Protection Agency advises radon mitigation interventions for residential buildings with indoor radon concentrations exceeding the threshold level of 4 pCi/L. Despite considerable research assessing the technical effectiveness of radon mitigation systems, there remains a gap in understanding their broader influence on occupant behavior and preferences in residential design. This study aims to investigate the impact of residing in radon-mitigated homes within the Commonwealth of Kentucky—an area known for elevated radon concentrations—on occupants’ preferences regarding healthy home design attributes. The objectives of this research are twofold: firstly to determine if living in radon-mitigated homes enhances occupant awareness and consequently influences their preferences toward health-related home attributes and secondly to quantitatively evaluate and compare the relative significance homeowners assign to health-related attributes such as indoor air quality, thermal comfort, and water quality relative to conventional attributes including home size, architectural style, and neighborhood quality. The overarching purpose is to explore the potential role radon mitigation initiatives may play in motivating occupants towards healthier home construction and renovation practices. Using choice-based conjoint (CBC) analysis, this paper compares preferences reported by homeowners from radon-mitigated homes against those from non-mitigated homes. While the findings suggest a relationship between radon mitigation and increased preference for indoor air quality, the cross-sectional design limits causal interpretation, and the possibility of reverse causation—where health-conscious individuals are more likely to seek mitigation—must be considered. The results provide novel insights into how radon mitigation efforts might effectively influence occupant priorities towards integrating healthier design elements in residential environments.

1. Introduction

Radon is a naturally occurring, odorless radioactive gas recognized as a significant public health hazard [1]. Indoor radon exposure constitutes the second leading cause of lung cancer in the United States, responsible for approximately 23,000 deaths annually [2,3,4,5,6]. Although eleven states mandate radon testing and mitigation for specific building types, no state requires such measures for single-family homes. Research indicates that while general awareness of radon exists among Americans, a comprehensive understanding of associated health risks and appropriate testing methods remains limited [7]. This knowledge gap is particularly pronounced in areas with insufficient educational outreach and limited resources [8]. Conversely, higher levels of awareness typically correlate with historically elevated radon concentrations [9].
The U.S. Environmental Protection Agency (EPA) has established an action threshold for indoor radon at 4.0 pCi/L [4]. In Kentucky, the average indoor radon level significantly exceeds this benchmark, measured at approximately 7.4 pCi/L [10]. An estimated one-third of Kentucky homes surpass the EPA’s recommended action level, as illustrated by the Kentucky radon distribution map (Figure 1). The Kentucky radon map illustrates estimated radon potential across the state by county, categorized into three zones based on expected indoor radon levels (measured in Bq/m3). Zone 1 (>148 Bq/m3) indicates the highest risk, while Zone 3 (<74 Bq/m3) indicates the lowest. This zoning helps visualize areas where residents may be more likely to experience elevated radon exposure. Given Kentucky’s housing stock of roughly 1.6 million single-family homes, approximately 533,000 residences may exhibit elevated radon concentrations. Recent research by the Kentucky Geological Survey and the University of Kentucky’s BREATHE program identified over 70,000 homes with dangerously high radon levels, highlighting the critical necessity for ongoing testing and mitigation initiatives.
Modern radon mitigation systems use a source control strategy. They operate by creating a depressurized zone beneath the building, which captures radon gas. The collected gas is then vented outside through a system of pipes and a fan connected to this depressurized area [2,11], as illustrated in (Figure 2). Effective radon mitigation strategies have been demonstrated to substantially reduce radon concentrations, thereby enhancing residential safety. Nonetheless, given the current low frequency of home testing across Kentucky, there is an imperative need for increased public awareness and widespread testing campaigns to mitigate the health risks associated with radon exposure [7,12,13].
Sustainability 17 06543 g001
Figure 1. Kentucky radon map by county [14].
Figure 1. Kentucky radon map by county [14].
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Sustainability 17 06543 g002
Figure 2. Radon mitigation system in a house in Bowling Green, Kentucky (photographed by the author).
Figure 2. Radon mitigation system in a house in Bowling Green, Kentucky (photographed by the author).
Sustainability 17 06543 g002

1.1. Health-Related Home Design Attributes

The healthy building concept advocates for the design and maintenance of indoor environments that enhance occupant health, well-being, and productivity [15,16]. This paradigm encompasses elements such as indoor air quality, lighting, thermal comfort, acoustics, and the utilization of non-toxic building materials. A healthy home integrates systems and materials that support respiratory health, safety, access to clean water, and overall wellness. Central features include mechanical ventilation systems, air purification units, humidity control, and the use of low-VOC (volatile organic compound) materials to limit exposure to indoor pollutants [16,17,18]. In radon-prone regions, incorporating radon-resistant construction methods and mitigation technologies is imperative. Access to safe drinking water—enabled through high-efficiency filtration systems—is also a key component of healthy housing [19]. Furthermore, thermal comfort, achieved through appropriate insulation and advanced temperature control, is a crucial determinant of residential health and satisfaction [20].
In Kentucky, the application of healthy building principles is particularly critical due to prevalent environmental pollutants. These include radon emissions from subsurface uranium decay, tropospheric ozone produced by industrial emissions, and airborne coal ash resulting from power generation. Implementing healthy building design in this context can mitigate exposure to these hazards. For instance, the integration of radon-resistant construction techniques and adherence to regular testing protocols can address elevated indoor radon levels. Educational programs led by institutions such as the Kentucky Geological Survey and the University of Kentucky’s BREATHE initiative serve to enhance public awareness and foster adoption of health-promoting building practices.

1.2. Non-Health-Related Home Design Attributes

In contrast, non-health-related home design attributes primarily focus on lifestyle preferences, spatial functionality, and aesthetic appeal. These factors are often shaped by cultural, economic, and demographic considerations. Home size, typically quantified in square footage, significantly influences both usability and comfort. Larger homes are generally associated with greater accommodation for families and activities, whereas smaller residences are valued for their efficiency and lower operational costs [21,22]. Architectural style—encompassing modern, traditional, and contemporary forms—plays a central role in personalizing the home environment and enhancing visual appeal [23].
Additionally, neighborhood quality is a critical determinant in home selection, encompassing access to educational institutions, green spaces, transportation infrastructure, and perceptions of safety. These community-level attributes contribute to overall residential satisfaction and social cohesion community [24,25,26]. While these elements do not directly influence indoor environmental quality, they remain integral to broader considerations of housing desirability and occupant well-being. This research aims to investigate the impact of residing in radon-mitigated homes within the Commonwealth of Kentucky—an area known for elevated radon concentrations—on occupants’ preferences regarding healthy home design attributes. The objectives of this research are twofold: firstly to determine if living in radon-mitigated homes enhances occupant awareness and consequently influences their preferences toward health-related home attributes and secondly to quantitatively evaluate and compare the relative significance homeowners assign to health-related attributes such as indoor air quality, thermal comfort, and water quality relative to conventional attributes including home size, architectural style, and neighborhood quality. The overarching purpose is to explore the potential role radon mitigation initiatives may play in motivating occupants towards healthier home construction and renovation practices.

2. Method

This study employs the choice-based conjoint (CBC) method, a robust analytical tool frequently utilized in environmental design research to elucidate user preferences across a range of hypothetical design scenarios. CBC enables researchers to infer the underlying value participants assign to individual attributes by presenting respondents with a series of trade-off decisions among attribute bundles [27]. This approach has been widely adopted in various domains, including urban green space planning and sustainable building evaluation. For example, Alves et al. (2008) applied CBC to investigate elderly users’ preferences for park features in the United Kingdom [28], while Zieba et al. (2013) employed the method to assess demand for sustainable office spaces in Poland [29]. Similarly, Mansour and Radford (2016) used CBC to explore preferences for experiential versus environmental design elements in buildings varying in sustainability performance [30]. CBC’s strengths include its capacity to simulate real-world decision-making processes and capture interactions among attributes [31]. However, limitations such as task complexity, potential respondent fatigue, and the need for relatively large sample sizes have been identified [32].
Respondents evaluate alternatives based on decision rules that reflect varying degrees of importance placed on each attribute. From these evaluations, utility values are derived to quantify the relative importance of specific attributes within a given design set [32]. Compared to other preference elicitation methods such as rating scales and best–worst scaling (BWS), choice-based conjoint (CBC) analysis offers a more realistic representation of how individuals make decisions. Rating scales ask respondents to evaluate items independently, which can lead to scale bias and limited insight into trade-offs between attributes. Best–worst scaling improves on this by forcing respondents to make relative judgments, but it still does not fully capture the complexity of multi-attribute decision making. In contrast, CBC presents respondents with sets of options and asks them to choose the one they prefer, closely mimicking real-world purchasing or selection behavior where trade-offs are implicit. This approach yields richer data on how individuals value different features in combination, making CBC especially useful for modeling consumer choice and predicting market behavior.
On the other hand, there are known methodological limitations associated with choice-based conjoint (CBC) analysis. Although CBC is widely used for eliciting preferences in housing and health research, it is inherently based on hypothetical scenarios, which may not perfectly translate to real-world behavior. The cognitive load involved in repeated trade-off decisions can lead to respondent fatigue, particularly when multiple attributes and levels are presented. In our study, we limited the design to six attributes with three levels each to reduce complexity.
In the context of this study, healthy home design attributes include the use of low-emission construction materials, advanced heating, ventilation, and air conditioning (HVAC) systems, mitigation strategies for airborne contaminants (e.g., radon and asbestos), thermal comfort optimization, and access to clean drinking water [33]. These health-oriented features increasingly influence property values, particularly when considered alongside traditional design preferences such as home size, architectural style, and neighborhood characteristics.
The CBC experiment presented in this study was designed to assess the relative importance of three health-related home attributes—indoor air cleanliness, thermal comfort, and water quality—and three conventional attributes—square footage, building style, and neighborhood quality. These attributes were specifically selected because they align with the scope and context of the study. As a heavily industrialized state with a manufacturing-driven economy, Kentucky faces concerns related to air and water quality. Additionally, Kentucky’s subtropical climate—with hot, humid summers and cold winters—makes thermal comfort a critical factor in healthy building design. Furthermore, the design attributes most relevant to building occupants were identified based on a comprehensive review of the literature. The six attributes were chosen based on a review of the literature, expert input, and a balance between cognitive load and experimental efficiency. A pilot test was conducted with 20 participants to assess the clarity, relevance, and burden of the attributes and levels. Based on this feedback, we finalized the six most consistently understood and policy-relevant attributes. Participants were asked to self-report whether their home had a radon mitigation system installed.
The choice experimental design was generated using Sawtooth Software Lighthouse Studio version 9.15.0, hosted in the Environmental Design Laboratory at the School of Engineering and Applied Sciences at Western Kentucky University. A CBC survey was designed to collect responses from 300 Kentucky residents, evenly divided between occupants of radon-mitigated and non-mitigated homes. Each respondent had to complete ten choice tasks, with each task requiring a selection from three hypothetical attribute bundles. Data analysis was performed using hierarchical Bayes estimation, enabling detailed modeling of individual-level preferences.
The target subjects for the survey were intentionally selected to be diverse, aiming to reflect the broader population of Kentucky residents. To support this goal, the digital survey link was distributed through various listservs associated with organizations such as Western Kentucky University, the city of Bowling Green, and homeowner associations across different towns and smaller communities throughout Kentucky. However, in compliance with IRB requirements for confidentiality, the survey was conducted anonymously and did not collect any identifying information, including participant addresses or personal details. As a result, the inability to verify specific characteristics of the sample population presents a limitation of the study since no demographic data were gathered to confirm the diversity of the respondents.
Participants were introduced to a hypothetical scenario in which a developer is planning a new residential community in Kentucky, Table 1 shows the conjoint choice attributes and levels. Respondents were asked to select preferred building designs based on sets of six design attributes or to opt out entirely by selecting “none of the above”. Conjoint sets were generated using a randomized, computer-assisted design strategy ensuring orthogonality, level balance, and minimal overlap [34]. Sawtooth Software was employed for both survey generation and data analysis. A total of 300 unique versions of the survey were administered online, each containing 10 choice sets along with basic demographic data, only asking them to provide their gender and age. Distribution channels included organizational listservs and community groups, with a notable portion of responses sourced from faculty and staff at Western Kentucky University. At the beginning of the questionnaire, each participant declared whether his or her home is mitigated or non-mitigated against radon. Table 2 shows the participant’ characteristics.

2.1. Attribute Identification and Experimental Design

Perceptions of residential environments are shaped by a multitude of factors, including architectural style, size, and neighborhood context. Research indicates that homes function not only as physical structures but also as socio-cultural and psychological constructs influenced by environmental, technological, and social dimensions [35]. The built environment, particularly its design and spatial configuration, plays a substantial role in shaping individuals’ sense of security and overall quality of life [36].
In contrast, environmental design attributes such as indoor air quality, thermal comfort, and water quality may not be immediately salient to building occupants due to their often intangible nature. For example, indoor air pollutants such as radon are odorless and cannot be detected through human senses, which limits public awareness of their potential harm [37,38]. Nonetheless, building systems—including ventilation design and material selection—significantly influence pollutant concentrations [39].
Thermal comfort is similarly complex, shaped by a combination of physiological, environmental, and psychological variables including air temperature, humidity, air movement, clothing insulation, and metabolic rate [40,41]. Individual responses to thermal conditions may vary widely even within identical environments [42] and are often modulated by contextual and subjective factors [43]. Comfort-related perceptions have been linked to cognitive performance, overall health, and user satisfaction [44].
Water quality is frequently judged based on sensory cues such as taste, odor, and appearance. However, these perceptions may not accurately reflect the actual safety or cleanliness of drinking water. Public perceptions are often shaped by information availability, institutional trust, and prior experience [45,46]. Despite these limitations, water quality remains a critical concern for building users [47].
The aim of this study is to evaluate the relative importance of environmental attributes—namely indoor air cleanliness, thermal comfort, and water quality—in comparison to conventional design attributes such as usable area (square footage), architectural style, and neighborhood quality. Furthermore, this study investigates whether these attribute preferences differ between occupants of radon-mitigated and non-mitigated homes in Kentucky. In this context, utility refers to the perceived value or effectiveness of a specific design attribute in fulfilling occupant needs [48].
Perceptions of residential environments and the importance placed on health-related housing attributes are shaped by a range of individual and contextual factors. Past health experiences, for example, can significantly influence how residents prioritize specific design elements; individuals with asthma or other respiratory conditions may place heightened importance on indoor air quality and ventilation systems. Environmental awareness also plays a crucial role, as residents who are more informed about sustainability and climate-related issues may be more likely to value energy efficiency, natural lighting, and the use of non-toxic building materials. Additionally, socioeconomic status often determines both access to and expectations of housing quality. Lower-income individuals may prioritize affordability and basic functionality over more ideal health-promoting features, while higher-income residents may have the means to seek out or retrofit homes with advanced comfort and wellness systems. Together, these factors contribute to varied perceptions of what constitutes a “healthy” home and underscore the need for residential design strategies that are flexible, inclusive, and responsive to diverse populations.
In this research, attribute selection was guided by two primary criteria: (1) the attribute’s ability to confer tangible benefits to occupants and (2) the attribute’s status as an experience-based feature that can be meaningfully evaluated by end users. For environmental attributes, indoor air cleanliness was defined as a product of effective envelope tightness and HVAC performance; thermal comfort as the result of insulation quality and environmental control; and water quality as the perceived availability of safe drinking water. Conventional attributes included square footage as a proxy for spatial utility, architectural style as an indicator of aesthetic and socioeconomic preference, and neighborhood quality as a reflection of community amenities and prestige. Table 1 shows the conjoint analysis attributes and levels.

2.2. Data Collection and Analysis

Of the more than 3000 individuals who received the survey link via institutional and community email listservs, 276 respondents initiated participation. Following data cleaning, 47 responses were excluded; responses were excluded if they contained incomplete choice tasks or exhibited patterns indicative of random or inattentive answering, for example, selecting the same option repeatedly or completing the survey in an implausibly short amount of time. This yields to the final sample of 229 valid responses. Among these, 79 participants were homeowners residing in radon-mitigated houses, while the remaining 150 respondents were occupants of non-mitigated houses. Table 2 shows the participant’ characteristics.
The choice-based data were analyzed using hierarchical Bayes (HB) estimation, implemented via the Sawtooth Software platform. This approach enables the estimation of individual-level utility parameters despite a limited number of observations per respondent, thus improving the precision and robustness of inferred preferences relative to aggregate models [30]. HB estimation facilitates the computation of individual-level part-worth utilities and attribute importance scores across the sample population.
The CBC/HB model employed in this study operates at two levels. At the population level, it assumes that individual-level part-worth vectors (βi) are distributed according to a multivariate normal distribution defined by a mean vector (α) and a variance–covariance matrix (D):
βi ~ Normal (α, D)
where βi = vector of part-worth utilities for respondent i; α = vector of means of the population distribution; D = covariance matrix of the population distribution.
At the respondent level, the likelihood of selecting a specific design alternative within a choice task is modeled using the multinomial logit function:
Pk = exp(xk′βi)/Σj exp(xj′βi)
where Pk = probability that respondent i selects alternative k; xk = attribute vector describing alternative k; xj = attribute vectors for all other alternatives in the task.
The HB algorithm iteratively estimates the parameters α, D, and βi through Bayesian updating, yielding both aggregate and individual-level estimates of preferences. This modeling framework allows for the accurate quantification of the relative importance participants assign to each design attribute, facilitating detailed interpretation of preference heterogeneity within and across respondent subgroups.

3. Results

Part-worth utilities and attribute importance scores are key outputs of a conjoint analysis that help interpret how individuals value different features of a product or decision scenario. Part-worth utilities represent the estimated preference or utility that respondents assign to each level of an attribute. Higher utility values indicate greater preference, while negative values suggest lower desirability relative to the baseline. These scores are typically scaled so that the sum of utilities within each attribute is zero, allowing for meaningful comparisons within attributes.
Attribute importance scores, on the other hand, indicate the relative weight or influence of each attribute in the overall decision-making process. They are calculated by taking the range of part-worth utilities within each attribute and expressing it as a percentage of the total utility range across all attributes. This provides insight into which attributes had the greatest impact on participants’ choices. Together, part-worth utilities and importance scores help identify not only which features matter most but also how different levels within those features are perceived—making them valuable tools for prioritizing design, policy, or product development decisions.
In this research, attribute importance scores were derived from the range of part-worth utilities within each attribute category and indicate the relative weight that respondents placed on different home design factors during the decision-making process. These scores are normalized to collectively sum to 100%, thereby enabling comparison across attributes and subpopulations. Table 3 presents the computed importance values for each attribute among three groups: residents of radon-mitigated homes, residents of non-mitigated homes, and the total sample.
Across all groups, indoor air cleanliness emerged as the most influential attribute, followed by house size, water quality, and thermal comfort. Building style and neighborhood quality were consistently ranked as the least important factors. These findings suggest that within regions subject to elevated indoor radon exposure, homeowners assign considerable value to health-promoting design features, particularly those associated with air and water quality, in addition to conventional priorities such as usable square footage.
Specifically, indoor air cleanliness was assigned the highest relative importance by both subgroups, with respondents from mitigated homes attributing substantially more weight to this attribute (mitigated = 45.01%) compared to those from non-mitigated homes (33.97%). This disparity may reflect the heightened awareness among individuals who have undergone radon mitigation, or alternatively, it may indicate that individuals with greater awareness are more likely to pursue mitigation interventions.
House size (mitigated = 16.35%; non-mitigated = 19.14%) was the second most important attribute across both groups. Combined, indoor air cleanliness and house size accounted for more than 50% of the total decision weight in both cohorts.
Interestingly, water quality (mitigated = 11.91%; non-mitigated = 16.77%) and thermal comfort (mitigated = 11.38%; non-mitigated = 15.16%) were ranked as the third and fourth most important attributes, respectively. Meanwhile, building style (mitigated = 9.03%; non-mitigated = 8.74%) and neighborhood quality (mitigated = 6.32%; non-mitigated = 6.22%) received the lowest importance scores, suggesting that these aesthetic and contextual features are less influential in occupant decision making relative to environmental health considerations.
A notable finding of this study is that respondents living in radon-mitigated homes assigned lower importance to water quality and thermal comfort compared to their non-mitigated counterparts. One potential explanation is that individuals who have already taken action to address a significant indoor environmental hazard—such as radon—may perceive their homes as generally healthier or safer, thereby reducing concern for other environmental factors. This sense of proactive mitigation may foster a perception of overall residential adequacy, leading to diminished sensitivity to other health-related housing attributes. Alternatively, these respondents may prioritize air-related issues due to heightened awareness of indoor air quality risks, inadvertently placing less emphasis on water quality or thermal comfort. This finding suggests that residents’ past experiences with environmental interventions can shape their perceptions and priorities in complex ways. Future research could explore how specific mitigation actions influence risk perception and attribute valuation across diverse environmental domains as well as investigate whether similar patterns emerge for other interventions, such as mold remediation or energy efficiency upgrades. Table 4 shows the aggregate results of the conjoint analysis. The part-worth utilities of building design attributes for occupants of mitigated and non-mitigated houses and a mixed population are illustrated in Figure 3. The degree of importance of building design attributes for occupants of mitigated and non-mitigated houses and a mixed population are illustrated in Figure 4.

4. Study Limitations

This study has several limitations. First, its cross-sectional design and reliance on stated preferences limit causal interpretation. While differences in preferences between mitigated and non-mitigated households were observed, these may reflect self-selection—health-conscious individuals may be more likely to install mitigation systems and value air quality features. Mitigation status was self-reported and verified through follow-up questions but remains subject to recall bias. Renovation history, which could influence awareness and preferences, was not captured.
Second, generalizability is limited due to the sample composition. A large proportion of participants were university-affiliated, likely skewing the sample toward higher education and health literacy levels. Although recruitment included urban and rural outreach, the final sample is not fully representative of Kentucky homeowners. Demographic variables such as income, education, and homeownership duration may confound results, and although exploratory analyses were performed, the study was not powered to fully control for these factors.
Finally, it is important to note that, due to the cross-sectional nature of the study and the self-selection of participants, causality cannot be inferred. The observed preference for indoor air quality among mitigated homeowners may reflect pre-existing health awareness that prompted mitigation rather than being a direct outcome of the mitigation experience itself.

5. Conclusions

Kentucky has implemented several radon mitigation initiatives to address high radon levels in homes statewide, spearheaded by organizations such as the Kentucky Radon Program, the University of Kentucky’s BREATHE program, and the Kentucky Geological Survey. The Kentucky Radon Program prioritizes public education through campaigns and provides residents with affordable or free radon testing kits. Additionally, the program collaborates closely with local health departments and community organizations to enhance awareness and inform homeowners about radon risks and effective mitigation measures.
This study explored an additional benefit of radon mitigation efforts in Kentucky, focusing on how mitigation influences homeowner preferences regarding healthy home attributes. Specifically, it examined preferences for indoor air cleanliness, water quality, and thermal comfort in comparison to conventional attributes like house size, building style, and neighborhood quality. Using choice-based conjoint (CBC) analysis, the study compared responses from homeowners in mitigated homes versus those in non-mitigated homes, providing fresh insights into how radon mitigation impacts homeowner priorities related to building design.
The findings revealed a strong preference for indoor air quality, specifically air cleanliness, among both homeowner groups. House size was ranked as the second-most important attribute, followed by thermal comfort and water quality. Home style and neighborhood quality were considered least important. Notably, respondents from mitigated homes expressed a significantly higher preference for indoor air quality than those from non-mitigated homes, suggesting an increased awareness and appreciation for this attribute following mitigation. Surprisingly, homeowners of non-mitigated homes placed relatively higher importance on thermal comfort and water quality.
These results offer valuable insights for developers, home designers, construction professionals, and public health officials, highlighting an added benefit of radon mitigation initiatives in Kentucky. While mitigation efforts effectively raise awareness of indoor air quality, they appear less influential in motivating interest in other healthy home attributes. Therefore, additional educational programs are recommended to inform homeowners comprehensively about various healthy building choices that enhance productivity, improve well-being, and ultimately save lives.
Whether heightened awareness of indoor air quality among homeowners is a result of living in mitigated homes or due to pre-existing awareness prompting mitigation efforts, the implication is clear: increasing radon mitigation efforts will elevate homeowner appreciation of indoor air quality as an essential aspect of a healthy living environment.
To build on these findings, actionable strategies should be implemented to integrate health-promoting features into residential design and housing policy, particularly in high-radon-risk areas. Local governments and planning agencies could incentivize the incorporation of radon-resistant construction techniques and enhanced ventilation systems in new housing developments through building codes or tax incentives. Design professionals should prioritize healthy indoor environments by incorporating air purification technologies, low-emission materials, and real-time air quality monitoring into home design standards. Moreover, policy efforts could require mandatory radon testing during home sales and rentals, especially in Zone 1 areas, alongside public campaigns that link radon mitigation with broader indoor health benefits. By embedding these features into both public policy and residential construction practices, Kentucky can promote healthier living conditions while reinforcing the value of radon mitigation as part of a comprehensive approach to occupant well-being.

Author Contributions

Conceptualization, O.E.M.; Methodology, O.E.M.; Validation, O.E.M.; Investigation, L.C.; Resources, L.C.; Data curation, O.E.M. and O.M.; Writing—original draft, O.E.M.; Writing—review & editing, O.E.M.; Visualization, O.M.; Project administration, O.E.M. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the United States Environmental Protection Agency [EPA Grant Number: SU840410, 2022] and Western Kentucky University.

Institutional Review Board Statement

This research has been reviewed and approved by the Western Kentucky University institutional review board (WKU IRB # 20-111) on 8 November 2023.

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

The data presented in this study are available on request from the corresponding author.

Acknowledgments

The authors would like to express their gratitude to the United States Environmental Protection Agency and Western Kentucky University for their financial support of this research. This support has been instrumental in advancing studies aimed at promoting health in the built environment. The authors also extend their sincere thanks to all participants who generously contributed their time to complete the survey; without their involvement, this study would not have been possible.

Conflicts of Interest

The authors declare no conflict of interest.

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Sustainability 17 06543 g003
Figure 3. The part-worth utilities of building design attributes for occupants of mitigated and non-mitigated houses and a mixed population.
Figure 3. The part-worth utilities of building design attributes for occupants of mitigated and non-mitigated houses and a mixed population.
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Figure 4. The degree of importance of building design attributes for occupants of mitigated and non-mitigated houses and a mixed population.
Figure 4. The degree of importance of building design attributes for occupants of mitigated and non-mitigated houses and a mixed population.
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Table 1. Conjoint Choice Attributes and Levels.
Table 1. Conjoint Choice Attributes and Levels.
Main AttributesLevels of Attributes
Level 1Level 2Level 3
Air CleanlinessA house with indoor air quality lesser than your current house; there is a potential of high level of indoor radon and history of harmful construction materialsA house with indoor air quality similar to your current houseA house with indoor air quality better than your current house; the house is mitigated against radon gas; the house is built with healthy construction materials
Thermal ComfortA house that provides you with less thermal comfort than your current house; it is not well insulated, with lower-quality heating and cooling systemsA house that provides you with thermal comfort similar to your current houseA house that provides you with better thermal comfort than your current house and is well insulated, with higher-quality heating and cooling systems
Water QualityA house with drinking water quality less than your current houseA house with drinking water quality similar to your current houseA house with drinking water quality better than your current house
House Size (square footage)Smaller-sized house; it has the same number of rooms, bathrooms, and service spaces, with less total square footageSame-sized house; it has the same number of rooms, bathrooms, and service spaces, with total square footage similar to your current houseBigger-sized house; it has the same number of rooms, bathrooms, and service spaces, with more total square footage
Building StyleA house that is designed with materials, colors, and style less desirable to you than your current houseA house that is designed with materials, colors, and style desirable to you same as your current houseA house that is designed with materials, colors, and style more desirable to you than your current house
Neighborhood QualityA house located in a neighborhood with open spaces, sidewalks, and landscape design quality less than your current neighborhoodA house located in a neighborhood with open spaces, sidewalks, and landscape design quality similar to your current neighborhoodA house located in a neighborhood with open spaces, sidewalks, and landscape design quality better than your current neighborhood
Table 2. Conjoint analysis survey participant characteristics.
Table 2. Conjoint analysis survey participant characteristics.
Mitigated Houses
N = 79		Non-Mitigated Houses
N = 150
FrequencyPercentageFrequencyPercentage
Gender
Male5873.4%9462.7%
Female2126.6%5637.3%
79100150100
Age
18–30810.1%2718.0%
31–403544.4%6543.3%
41–502227.8%4630.7%
51–601417.7%128.0%
>6000.0%00.0%
Prefer not to answer00.0%00.0%
79100150100
Table 3. Attributes importance scores for radon mitigated versus non-mitigated house occupants.
Table 3. Attributes importance scores for radon mitigated versus non-mitigated house occupants.
Design AttributeAverage Importance
for Mitigated House Occupants (N = 79)		Average Importance
for Non-Mitigated House Occupants (N = 150)		Average Importance
for Mitigated and Non-Mitigated House Occupants (N = 229)
Clean Indoor Air45.0033.9738.83
Thermal Comfort11.3815.1613.58
Water Quality11.9116.7714.75
House Size16.3519.1418.29
Building Style9.038.748.34
Neighborhood Quality6.326.216.21
Table 4. Aggregate Results of the Conjoint Analysis (N = 229).
Table 4. Aggregate Results of the Conjoint Analysis (N = 229).
Mitigated Houses
N = 79		Non-Mitigated Houses
N = 150		Combined
N = 229
AttributeLevelAverage UtilitiesRelative ImportanceAverage UtilitiesRelative ImportanceAverage UtilitiesRelative Importance
Clean Indoor AirHigh126.1145.01%95.1333.97%106.6538.83%
Medium10.095.649.18
Low−136.2−100.76−115.82
Thermal ComfortHigh16.4011.38%28.8315.16%24.7113.58%
Medium13.6717.8416.50
Low−30.07−46.68−41.21
Water QualityHigh16.8711.91%37.3816.77%29.0914.75%
Medium3.983.856.21
Low−20.85−41.23−35.31
House SizeHigh28.8816.35%40.7719.14%37.6818.29%
Medium18.045.149.33
Low−46.92−45.91−47.01
Building StyleHigh22.949.03%16.378.74%18.888.34%
Medium5.616.995.59
Low−28.55−23.35−24.46
Neighborhood QualityHigh58.836.32%27.446.22%10.956.21%
Medium2.11−1.710.42
Low−12.66−6.53−11.36
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Mansour, O.E.; Cing, L.; Mansour, O. Contextualizing Radon Mitigation into Healthy and Sustainable Home Design in the Commonwealth of Kentucky: A Conjoint Analysis. Sustainability 2025, 17, 6543. https://doi.org/10.3390/su17146543

AMA Style

Mansour OE, Cing L, Mansour O. Contextualizing Radon Mitigation into Healthy and Sustainable Home Design in the Commonwealth of Kentucky: A Conjoint Analysis. Sustainability. 2025; 17(14):6543. https://doi.org/10.3390/su17146543

Chicago/Turabian Style

Mansour, Osama E., Lydia (Niang) Cing, and Omar Mansour. 2025. "Contextualizing Radon Mitigation into Healthy and Sustainable Home Design in the Commonwealth of Kentucky: A Conjoint Analysis" Sustainability 17, no. 14: 6543. https://doi.org/10.3390/su17146543

APA Style

Mansour, O. E., Cing, L., & Mansour, O. (2025). Contextualizing Radon Mitigation into Healthy and Sustainable Home Design in the Commonwealth of Kentucky: A Conjoint Analysis. Sustainability, 17(14), 6543. https://doi.org/10.3390/su17146543

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