Abstract
Background:
Radon is the second leading cause of lung cancer in the U.S., the leading cause of lung cancer in nonsmokers, and is estimated to cause 21,000 deaths every year. Radon is especially prevalent in the upper Midwest. This study aimed to assess radon testing and mitigation practices among residential homeowners, landlords, and school districts in Wisconsin.
Methods:
Two survey sample datasets were used to assess radon testing and mitigation in residential homes: the Survey of the Health of Wisconsin (SHOW) and Wisconsin Behavioral Risk Factor Surveillance System (BRFSS) survey. Wisconsin landlords and school administrators were surveyed to assess radon testing and mitigation in rental properties and schools, respectively.
Results:
Approximately 30% of Wisconsin homeowners (22.1% from SHOW and 39.9% from BRFSS) have tested their properties for radon. Similarly, 31.0% of Wisconsin landlords (40/129) and 35.1% of Wisconsin school districts (78/222) have tested their schools for radon. Of homeowners with elevated radon, about 60% mitigated. School districts whose radon levels tested high most commonly did not mitigate, with costs and/or lack of funding cited as the most common barrier.
Discussion:
Radon testing and mitigation practices are inadequate in Wisconsin, and future work will seek to determine the best methods to increase testing and mitigation and reduce radon-induced lung cancer deaths in Wisconsin.
INTRODUCTION
Radon is a naturally-occurring, colorless, odorless, radioactive, carcinogenic gas that comes from the soil. Radon is the largest source of background radiation, making up 37% of Americans’ total annual radiation exposure.1 Radon exposure is the second leading cause of lung cancer nation-wide, causing about 21,000 deaths per year in the U.S. and about 500 deaths per year in Wisconsin.2 The initial evidence for radon causing lung cancer comes from studies of thousands of uranium miners carried out over 50 years world-wide,3,4 and further evidence has been provided from residential studies.5–7 Radon also poses a risk to smokers and may actually synergize with smoking to cause lung cancer;8,9 indeed, some estimates suggest that a majority of radon-induced lung cancers occur in smokers.7
Radon in the home is often assessed at the point of real estate transactions by a certified professional. Alternatively, radon can be assessed using self-test kits, which can be purchased for about $10 from a local health department or hardware store. In Wisconsin, there are 17 local health departments that serve as radon information centers for the general public and test kits are made available at reduced rates. Results from test kits are used to populate an online interactive map that illustrates radon risk potential in the state (https://www.dhs.wisconsin.gov/radon/index.htm). Although high levels of radon have been detected in every state, the upper Midwest has some of the highest levels of radon in the country.10 The Environmental Protection Agency (EPA) recommends taking action to mitigate radon levels once indoor concentrations meet or exceed 4 pCi/L. However, there is no “safe” level of radon exposure. In Wisconsin, 29 out of 72 (40.3%) counties have a predicted average indoor radon screening level greater than 4 pCi/L, and the remaining 43 (59.7%) counties have a predicted average indoor radon screening level between 2 and 4 pCi/L.11 However, these data do not necessarily indicate geographic areas of highest risk, and it is recommended that all homes be tested for radon.
Fortunately, elevated indoor radon levels can be prevented or mitigated with a variety of strategies. Radon-resistant construction techniques can be implemented at the time of building construction, and the cost to the builder of including radon-resistant features in a new home during construction is typically less than the cost to mitigate the home after construction. After construction, elevated radon levels can be easily reduced with an active mitigation system, which is usually installed by a professional and costs about $1000.
Herein, we sought to assess awareness and knowledge of radon in Wisconsin and to determine what percentage of residents, landlords, and school districts in the state of Wisconsin have ever tested for radon and mitigated their building(s) if radon levels were high.
METHODS
Survey of the Health of Wisconsin (SHOW)
The Survey of the Health of Wisconsin (SHOW), collected from 2008-2013, has been previously detailed.12 The question “Have you tested for radon in this home? (yes, no, refused, don’t know)” was used to assess prevalence of radon testing. If respondents indicated “yes” they were subsequently asked “What was the result of this test?” Response options included: positive but below recommended action levels, positive but about, positive, but don’t remember recommended action level, or negative. Data were analyzed using SAS (version 9.4). Rao-Scott Pearson Chi-square tests were used to test for significant differences. Multiple logistic regression modeling was performed to assess the relative importance of select demographic factors. Analyses accounted for the clustering and stratification in the sampling design and were weighted to the adult population of Wisconsin age 21 to 74.
Wisconsin Behavioral Risk Factor Surveillance System (BRFSS)
The Wisconsin BRFSS is part of the national surveillance system coordinated by the Centers for Disease Control and Prevention (CDC) to measure adult health risk behaviors and health outcomes by random-digit-dialed landline and cellular telephone survey of residents aged 18 and older. Prevalence estimates from the core survey questions and state-added optional radon module were analyzed. Respondents were asked: “Are you aware of the health risks associated with exposure to radon?”, “Has your household air been tested for the presence of radon gas?”, and “Were the radon levels in your household above the Environmental Protection Agency’s recommendation action level of four picocuries per liter?” If respondents reported a value greater than the EPA’s action level (4 pCi/L), then they were asked: “In response to a high radon test, did you take any of the following actions (respondents were allowed to choose as many of the following choices that applied: re-test, have a mitigation system installed, no longer go in basement, do nothing, or do something else). BRFSS core survey demographics were analyzed with the radon module, including age (categorized as 18-34, 35-64, or 65 and over), homeowner status (categorized as homeowners, renters, or other), and geographic location in Wisconsin (Northern, Northeastern, Western, Southern, or Southeastern; Supplemental Figure 1A). Annual Wisconsin BRFSS data from 2014–2016 were combined to increase precision of estimates. Data were analyzed using SAS (version 9.4). Rao-Scott Pearson Chi-square tests were used to test for significant differences.
Survey of Landlords
A list of landlords in Wisconsin was obtained using the Wisconsin Housing Search (WIHousingSearch.org) database, which compiles a listing of rental housing throughout Wisconsin. Lists of landlords were collected from the following metropolitan areas in Wisconsin: Milwaukee, Madison, Green Bay, Kenosha, Racine, Appleton, Oshkosh, Eau Claire, Janesville, La Crosse, and Fond du Lac. These areas were chosen because they represent the largest population centers in Wisconsin (combine for approximately 25% of Wisconsin’s total population) and are geographically dispersed throughout Wisconsin. The Dane County Tenant Resource Center (tenantresourcecenter.org) provides a list of Madison’s management and rental companies, and this resource was used to supplement the list of landlords contacted in Madison. We randomly selected a subset of landlords within each metropolitan area and called the following number of landlords from each area: 30 from Milwaukee (12 completed responses, 40.0% response rate), 89 from Madison (26 completed responses, 29.2% response rate), 13 from Green Bay (11 completed responses, 84.6% response rate), 17 from Kenosha (13 completed responses, 76.5% response rate), 8 from Racine (7 completed responses, 87.5% response rate), 9 from Appleton (1 completed responses, 11.1% response rate), 11 from Oshkosh (10 completed responses, 90.9% response rate), 63 from Eau Claire (19 completed responses, 30.2% response rate), 14 from Janesville (9 completed responses, 64.3% response rate), 14 from La Crosse (11 completed responses, 78.6% response rate), and 14 from Fond du Lac (12 completed responses, 85.7% response rate). This yielded a total of 282 landlords that were contacted. 151 (53.5%) refused to participate, did not answer the phone after three attempts, did not respond to voice mails, or did not respond to an email if an email address was given during the initial phone call. This yielded a total of 131 completed responses. The survey questions are available in Supplemental Materials.
Survey of School Districts
Finally, public schools were surveyed to assess potential risks of exposure to radon among school children. A publicly-available list of school administrators was obtained from the Wisconsin Department of Public Instruction (DPI). A survey was emailed three times to these public school administrators of all districts in the state of Wisconsin (n = 443 administrators). This yielded 174 responses (39.1% response rate). Subsequently, administrators that did not respond were called . This survey yielded a total of 231 completed responses (final response rate of 52.1% of school districts in Wisconsin). A response was considered completed if all survey questions except for the free response questions were completed. Fifty-three responses (22.9%) were obtained from superintendents, 81 (35.1%) from directors/managers of buildings and grounds or facilities, 52 (22.5%) from other district administrators, and 45 (19.5%) from other staff. The survey questions are available in Supplemental Materials.
Statistics
Prior to the study, R (V 3.3.1) was used to calculate expected half-widths of Wald 95% confidence intervals based on various combinations of possible sample sizes and response proportions for both school districts and landlords. Expecting that the response proportion of respondents (for both landlords and school districts) that tested for radon would be 0.25, it was found that a survey sample of at least 73 schools and 73 landlords would result in confidence interval half-widths of approximately 0.1 (Supplemental Figure 1B–C).
RESULTS
Radon awareness, testing, and mitigation practices among Wisconsin residents
The SHOW study surveyed 3381 participants from 2008-2013, of whom 2753 reported having a basement in their home. Of those with basements, 22.1% (95% CI 20.0-24.3%) reported that they tested their home for radon, 65.2% (95% CI 62.3-68.1%) reported that they had not tested their home for radon and 12.6% (95% CI 10.6-14.6%) responded that they did not know if they had tested their home for radon (Figure 1, Table 1). This percentage did not differ significantly based on gender or urbanicity (Table 1). There was a trend toward greater testing rates for older respondents (Table 1) Also, respondents with higher educational attainment and higher per capita household income were significantly more likely to test for radon (Table 1). Multivariate analysis revealed higher education and home built before 1900 to be associated with testing for radon.
Figure 1. Survey of the Health of Wisconsin assessment of radon testing by Wisconsin residents.
(A) Treemap demonstrating the percentage of Wisconsin residents in the Survey of the Health of Wisconsin (SHOW) that have tested for radon and whether their tests were positive or negative. (B) Treemap demonstrating the percentage of Wisconsin residents in the Wisconsin Behavioral Risk Factor Surveillance System (BRFSS) survey who tested for radon, and mitigated if radon levels were high based on whether they are homeowners or renters.
Table 1.
Survey of the Health of Wisconsin (SHOW) assessment of radon testing.
| Tested | Not tested | Don’t know | |||||||
|---|---|---|---|---|---|---|---|---|---|
| N | Pct* | N | Pct* | N | Pct* | Chi Square P-value | OR**** | Regression P-value | |
| All participants with basements** | 637 | 22.1 (20.0-24.3) | 1770 | 65.2 (6.23-68.1) | 346 | 12.6 (10.6-14.6) | |||
| Age | |||||||||
| 21-39 | 166 | 18.6 (15.5-21.8) | 507 | 61.9 (57.2-66.5) | 178 | 19.5 (15.7-23.3) | <0.001 | 1.03 (0.67-1.56) | 0.91 |
| 40-54 | 241 | 25.2 (21.6-28.8) | 625 | 65.6 (61.1-70.1) | 82 | 9.2 (6.3-12.1) | 1.22 (0.92-1.64) | 0.17 | |
| 55-74 | 230 | 22.6 (19.3-25.9) | 638 | 69.0 (64.9-73.0) | 86 | 8.4 (6.4-10.3) | Ref | ||
| Gender | |||||||||
| Male | 273 | 22.3 (19.4-25.2) | 802 | 66.6 (62.7-70.5) | 131 | 11.1 (8.3-13.8) | 0.11 | 0.95 (0.76-1.19) | 0.63 |
| Female | 364 | 21.9 (19.3-24.6) | 968 | 63.9 (60.6-67.2) | 215 | 14.2 (11.9-16.5) | Ref | ||
| Race / ethnicity | |||||||||
| Non-hispanic white | 532 | 22.6 (20.2-25.0) | 1537 | 66.2 (63.4-68.9) | 277 | 11.2 (9.4-13.1) | 0.04 | Ref | |
| Non-hispanic black | 56 | 19.5 (12.7-26.4) | 120 | 57.7 (47.1-68.3) | 36 | 22.7 (12.0-33.5) | 1.60 (0.83-3.07) | 0.16 | |
| Hispanic | 17 | 20.5 (11.4-29.6) | 47 | 57.7 (37.1-78.3) | 13 | 21.8 (3.3-40.3) | 1.40 (0.68-2.92) | 0.36 | |
| Other | 32 | 18.7 (9.2-28.2) | 62 | 63.7 (53.4-74.0) | 20 | 17.6 (8.0-27.2) | 1.38 (0.65-2.94) | 0.40 | |
| Education | |||||||||
| High school degree or less | 148 | 17.0 (13.4-20.5) | 524 | 66.0 (60.7-71.4) | 116 | 17.0 (12.4-21.6) | <0.001 | 0.45 (0.32-0.64) | <0.01 |
| Some college or associate’s degree | 217 | 20.3 (17.2-23.4) | 680 | 66.8 (62.7-70.9) | 132 | 12.9 (10.0-15.9) | 0.67 (0.51-0.89) | 0.01 | |
| Bachelor’s degree or higher | 272 | 28.2 (24.2-32.2) | 565 | 62.9 (58.8-67.1) | 97 | 8.9 (6.7-11.1) | Ref | ||
| Poverty | |||||||||
| < 200% FPL | 125 | 15.2 (11.8-18.6) | 456 | 61.9 (57.3-66.5) | 159 | 22.9 (18.0-27.8) | <0.001 | 0.87 (0.56-1.36) | 0.54 |
| ≥ 200% FPL | 487 | 24.6 (21.8-27.5) | 1248 | 67.1 (63.7-70.5) | 159 | 8.3 (6.6-9.9) | Ref | ||
| Urbanicity (2010 Census)*** | |||||||||
| Urban | 407 | 22.0 (19.5-24.6) | 1107 | 63.9 (60.4-67.4) | 241 | 14.1 (11.4-16.8) | 0.05 | 1.00 (0.72-1.38) | 0.99 |
| Rural | 230 | 22.4 (18.2-26.6) | 663 | 68.1 (63.3-72.8) | 105 | 9.5 (7.3-11.7) | Ref | ||
| Wisconsin health region | |||||||||
| Southeastern | 230 | 23.9 (20.0-27.8) | 538 | 62.5 (56.7-68.2) | 117 | 13.6 (9.4-17.8) | 0.56 | 1.10 (0.72-1.67) | 0.66 |
| Southern | 124 | 21.2 (17.6-24.7) | 352 | 64.4 (59.7-69.1) | 75 | 14.4 (10.9-18.0) | 0.91 (0.60-1.36) | 0.64 | |
| Western | 63 | 19.5 (13.3-25.8) | 240 | 67.3 (59.6-75.0) | 54 | 13.1 (6.3-19.9) | 0.86 (0.51-1.46) | 0.57 | |
| Northern | 86 | 21.8 (15.8-27.8 | 250 | 69.9 (64.2-75.6) | 34 | 8.3 (5.6-11.0) | 0.92 (0.56-1.53 | 0.75 | |
| Northeastern | 134 | 22.0 (16.5-27.4) | 390 | 67.6 (61.2-74.0) | 66 | 10.4 (7.4-13.5) | Ref | ||
| Year of home construction | |||||||||
| Before 1900 | 51 | 15.8 (11.4-20.1) | 197 | 67.3 (60.8-73.7) | 41 | 17.0 (11.5-22.5) | 0.0003 | 0.61 90.39-0.94) | 0.03 |
| 1900 - 1950 | 133 | 20.5 (16.6-24.4) | 406 | 69.1 (64.7-73.5) | 67 | 10.4 (7.4-13.3) | 0.70 (0.47-1.05) | 0.09 | |
| 1951 - 1978 | 186 | 26.8 (22.2-31.5) | 416 | 62.5 (56.6-68.3) | 65 | 10.7 (7.0-14.4) | 1.08 (0.75-1.56) | 0.68 | |
| 1979 - 1990 | 82 | 28.8 (21.5-36.0) | 177 | 63.5 (56.1-71.0) | 28 | 7.7 (4.4-11.0) | 1.13 (0.69-1.85) | 0.62 | |
| 1991 - present | 138 | 26.6 (21.7-31.5) | 355 | 65.6 (60.4-70.9) | 49 | 7.8 (5.1-10.5) | Ref | ||
| Duration at current residence (years) | |||||||||
| < 1 | 38 | 13.7 (8.5-19.0) | 159 | 66.1 (58.8-73.4) | 56 | 20.2 (14.2-26.2) | <0.001 | 0.78 (0.42-1.47) | 0.44 |
| 1-4 | 132 | 21.3 (16.7-25.9) | 365 | 60.6 (54.8-66.4) | 105 | 18.1 (13.8-22.4) | 1.06 (0.68-1.67) | 0.79 | |
| 5-9 | 133 | 23.3 (18.3-28.2) | 377 | 67.5 (62.5-72.6) | 58 | 9.2 (6.7-11.7) | 0.84 (0.56-1.26) | 0.40 | |
| ≥ 10 | 332 | 24.3 (21.3-27.3) | 856 | 66.5 (62.4-70.6) | 121 | 9.2 (6.8-11.6) | Ref | ||
Row percentages weighted to represent the civilian, non-institutionalized population of WI age 21 to 74. The estimates also account for the stratification and clustering in the complex survey design.
The housing characteristics questionnaire only asked the radon test question to respondents who reported having a basement in their residence.
Urbanicity defined using Census 2010 urban rural classification; urban includes both urbanized areas and urban clusters and rural is comprised of all remaining areas.
Multiple logistic regression model of the response “Tested for radon,” adjusted for all of the variables in the table, as well as stratification and clustering in the complex survey design. Respondents who reported “Don’t know” are not included in this multiple logistic regression model.
Based on estimates from the 2014-2016 BRFSS sample, 73.4% of Wisconsin residents report being aware of the health risks associated with exposure to radon (Figure 1B). 80.4% of Wisconsin residents who own their home are aware of radon risks, compared to 54.7% of renters and 47.5%of those who reported living in other arrangements (Table 2). 39.9% of Wisconsin residents have tested their households for the presence of radon, which translates to approximately 1.34 million residents. Again, the testing rate was higher for homeowners (41.9%) compared to renters (33.9%) and residents who reported other living arrangements (28.7%) (Table 2). Of the Wisconsin residents who tested for radon, 12.5% found elevated levels of radon gas (above 4 pCi/L). Of those residents who reported elevated radon levels, 51.9% retested, 63.2% mitigated, 6.8% avoided the basement, 21.7% did nothing, and 20.4% did something else (respondents could select more than one choice). Twice as many homeowners as renters mitigated if they found an elevated test result (67.7% of homeowners versus 30.2% of renters and 51.7% of those in other living arrangements) (Table 2).
Table 2.
Wisconsin Behavioral Risk Factor Surveillance System (BRFSS) survey of radon awareness, testing, and mitigation.
| Radon Awareness | Radon Testing | Tested and Radon Was Elevated | Elevated Radon and Mitigated | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| N (weighted) | Pct | P Value | N (weighted) | Pct | P Value | N (weighted) | Pct | P Value | N (weighted) | Pct | P Value | |
| Age | ||||||||||||
| 18-34 years | 526,950 | 55.3 (52.6 - 58.0) | <0.001 | 344,326 | 39.8 (37.1 – 42.5) | 0.102 | 34,379 | 11.10 (8.4 – 13.9) | 0.347 | 19,241 | 60.2 (47.4 – 73.0) | 0.118 |
| 35-64 years | 1,438,601 | 79.2 (77.9 - 80.5) | 719,213 | 40.8 (39.3 – 42.3) | 89,963 | 13.20 (11.7 – 14.8) | 60,520 | 67.2 (61.4 – 73.1) | ||||
| 65+ years | 616,136 | 81.8 (80.3 - 83.3) | 273,668 | 37.6 (35.7 – 39.5) | 29,883 | 12.20 (10.1 – 14.3) | 15,683 | 54.6 (45.7 – 63.5) | ||||
| Region | ||||||||||||
| South | 686,735 | 72.7 (70.3 – 75.0) | <0.001 | 342,006 | 37.9 (35.5 – 40.4) | 0.001 | 31,982 | 10.10 (7.8 – 12.3) | 0.001 | 22,043 | 69.5 (59.2 – 79.9) | 0.047 |
| North | 254,969 | 81.1 (79.0 - 83.2) | 121,914 | 40.4 (37.9 – 43.0) | 12,236 | 10.80 (8.0 – 13.6) | 6,585 | 53.9 (39.2 – 68.5) | ||||
| West | 373,408 | 74.2 (71.7 - 76.7) | 175,830 | 36.5 (33.9 – 39.1) | 17,599 | 10.80 (7.9 - 13.7) | 8,624 | 48.4 (34.4 – 62.4) | ||||
| NE | 595,243 | 76.3 (74.2 - 78.3) | 321,721 | 43.3 (40.9 – 45.6) | 35,381 | 11.70 (9.6 – 13.9) | 23,673 | 70.4 (61.6 – 79.1) | ||||
| SE | 689,163 | 68.9 (66.6 – 71.1) | 382,789 | 40.5 (38.3 – 42.8) | 57,406 | 16.70 (14.0 – 19.4) | 34,519 | 62.0 (53.4 – 70.5) | ||||
| Living Situation | ||||||||||||
| Own | 2,094,690 | 80.4 (79.3 – 81.5) | <0.0001 | 1,069,648 | 42.0 (40.7 – 43.3) | <0.0001 | 131,405 | 12.9 (11.6 – 14.2) | 0.1908 | 88,531 | 67.7 (62.7 – 72.8) | <0.0001 |
| Rent | 444,974 | 54.7 (52.1 – 57.2) | 243,233 | 33.9 (31.4 – 36.5) | 19,693 | 10.0 (7.1 – 12.9) | 5099 | 30.2 (16.1 – 44.2) | ||||
| Other | 59,854 | 47.5 (40.8 – 54.2) | 31,380 | 28.8 (22.9 – 34.7) | 3507 | 12.7 (5.5 – 19.8) | 1814 | 51.7 (22.0 – 81.5) | ||||
P values are from Rao-Scott chi-square tests.
This study next assessed if there were differences in radon awareness based on age and geographic location (Supplemental Figure 1). Adults 65 years and older reported the greatest radon awareness (81.8%) compared to younger age groups, but there were no significant differences in testing and mitigation practices based on age (Table 2). When assessing potential differences based on geographic area, radon awareness was greatest in northern Wisconsin (81.1%) and lowest in southeastern Wisconsin (68.9%) (Table 2). Additionally, those from northeast Wisconsin were the most likely to report testing for radon (Table 2). Interestingly, those from southeast Wisconsin were most likely to report elevated radon levels yet were not the most likely to report mitigation if radon levels were high (Table 2). Those from south and northeast Wisconsin were the most likely to mitigate if radon levels were elevated (Table 2).
Radon testing and mitigation practices among landlords in Wisconsin
Next, this study assessed radon testing and mitigation practices by lessors/landlords/management companies in Wisconsin (Figure 2A). We find that 31.0% of surveyed landlords reported that they had ever tested at least one of their buildings, while 49.6% reported that they had never tested and 19.4% were unsure (Figure 2B). There is no significant trend in likelihood to test for radon based on the size of the landlord or management company (Supplemental Figure 2A). A majority of tests were performed using self-test kits (53.2% self-test kits versus 31.9% professional testing versus 14.9% unsure; Supplemental Figure 2B). 12.4% of landlords reported that their buildings have mitigation systems, while 43.8% reported that their buildings do not have mitigation systems (Supplemental Figure 2C). Lastly, 6.7% of landlords reported that their properties were built with radon-resistant construction compared to 36.5% who reported they did not use radon-resistant construction and 56.7% who were unsure (Supplemental Figure 2D).
Figure 2. Survey of radon testing and mitigation by landlords in Wisconsin.
(A) A map of Wisconsin demonstrating the distribution of landlords from which responses were obtained. The sizes of the red circles correlate with the number of completed responses that were obtained from each of the indicated metropolitan areas. (B) Percentage of landlords that have tested at least one of their buildings for radon.
Radon testing and mitigation practices in schools in Wisconsin
Lastly, this study assessed radon testing and mitigation practices by public school districts (Figure 3A). Of 231 completed responses, 35.1% of districts reported that all of their schools had been previously tested for radon, 8.1% of school districts reported that a subset of their schools had been previously tested for radon, 19.8% of school districts have not tested for radon, and 36.9% of school districts were unsure (Figure 3B). By examining school district size based on number of buildings and by enrollment, there is no significant difference in propensity to test for radon based on size of the district (Supplemental Figure 3A–B). Of 32 districts that reported elevated radon tests, 25.0% took some sort of action (e.g. mitigation, fresh air ventilation, or retested) while 46.9% of schools did nothing in response to a high radon test (Figure 3C). We also asked whether or not school districts installed radon mitigation systems in their schools, either during construction of the school or ex post facto. 79.2% reported no mitigation system, while only 2.1% reported a mitigation system in place.
Figure 3. Survey of radon testing and mitigation in schools in Wisconsin.
(A) A map of Wisconsin demonstrating the distribution of schools from which responses were obtained. Each red circle represents one district. (B) Percentage of schools that have tested at least one of their buildings for radon. (C) Actions that were taken by school districts who reported an elevated radon test. The absolute number of districts in each category is shown above each bar. Total n = 32. (D) Percent of school districts that reported the following barriers to radon testing and mitigation. Respondents were allowed to choose multiple barriers, if applicable. Total n = 188. Throughout the figure, bars represent percentages ± 95% confidence intervals, and the absolute number of response is shown above each bar.
Finally, potential barriers to radon testing and mitigation in schools were assessed (Figure 3D). The most common response was that no barriers exist (36.2% of respondents). The next most common reported barrier was cost or lack of funding (27.7% of respondents).
DISCUSSION
The results of this study demonstrate that approximately 30% of residential homeowners (22.1% from SHOW and 39.9% from BRFSS), 31.0% of landlords, and 35.1% of public school districts have tested for radon. Furthermore, of the buildings that have been tested, our data demonstrate that approximately 12.5% of buildings have elevated radon. Lastly, of those that reported elevated radon, 63% of residential homes and 25% of public school districts took actions to mitigate (unable to draw conclusion from landlords based on low number of tests with known results). As 73.4% of residents reported being aware of radon in the BRFSS data, it appears that awareness may not be the biggest barrier to testing in the residential setting. Previous studies have cited lack of perceived threat and cost as the biggest barriers to testing and mitigation.13 With regard to landlords, the biggest barrier to radon testing and mitigation appears to be awareness, as many landlords we surveyed were not aware of radon or were unsure of whether their buildings had ever been tested and/or mitigated. Additionally, some landlords reported that radon testing and mitigation was not their responsibility and thought the state or local government was responsible. Interestingly, of school districts that reported elevated radon levels, only about 25% took some sort of action. The most commonly cited barrier to radon testing and mitigation was lack of funding, suggesting that providing funding to public schools to test and mitigate could improve radon testing and mitigation. It may be particularly impactful to intervene in schools and protect children, as longer, less-intense exposures to radon are generally more carcinogenic than shorter, more-intense exposures.14 These results are similar to a recent study of radon testing practices in Minnesota schools, which found that 53 of 331 (16%) school districts report that they have tested classrooms for radon since 2012.15 Furthermore, the aforementioned EPA study of 927 schools nationwide estimated that over 70,000 classrooms in the U.S. were likely to have radon concentrations above the EPA’s action level of 4 pCi/L.16 These results add to existing literature by providing a relatively comprehensive assessment of radon testing and mitigation practices in residential dwellings and schools in an upper Midwest state with high radon levels and demonstrate potential areas of intervention to increase radon testing and mitigation.
A major barrier to radon testing and mitigation is a general lack of awareness and concern surrounding radon, and research and remediation programs have stalled.17 In fact, a recent review of CDC-funded National Comprehensive Cancer Control Programs found that approximately one-third of these grantees still do not include radon in their cancer control plans.18 In addition, survey data suggest that even among people who are aware of radon as a health hazard, only a small fraction live in a home that has been tested.19 A major challenge to communicating radon risk and promoting radon remediation is that the radon threat is inherently perceived as either being low or simply non-existent. Furthermore, the lack of sensory cues to alert people that radon is an immediate threat prevents people from taking action.13 Several studies around the U.S. have demonstrated a lack of radon awareness and action. Data from New York state suggest that about 1/5 of New York residents are aware of radon, and only 15% of this 1/5 had their homes tested.20 Similarly, a survey of Madison County, Alabama, demonstrated that 70.2% of households had heard of radon, but only 7.3% of houses had been tested for radon.21 Lastly, a study of Vermont residents who tested for radon and had elevated radon levels demonstrated that 43% mitigated.19 It is unclear how well these survey data can be extrapolated to the upper Midwest where radon levels are highest, and such a survey in Wisconsin has never been reported.
Current radon testing practices and cost of mitigation may increase health disparities. The risks of radon have traditionally only been mentioned with home sale or transfer, making renters less likely to be aware of such risks.22 Nearly twice as many renter-occupied households are below the poverty line (e.g. minorities, low income individuals) compared to owner-occupied households. The homeownership rate among white Americans is about 71% compared to about 41% for black Americans and about 47% for Hispanic Americans.23 Furthermore, those who rent may not have the financial resources to install a mitigation system and also do not own the property and may not have the authority to install a mitigation system. This radon disparity may also be true among homeowners, as a study in Illinois found that lower income and more rural households were less likely to have tested their homes for radon.24 One potential strategy to reduce disparities is to require landlords to test their properties for radon and mitigate if levels are elevated.
Wisconsin law currently requires disclosure of known prior radon testing during real estate transactions but does not require testing and/or mitigation at real estate transactions, by landlords, or by schools. Given the magnitude of the problem, current testing and mitigation policies and efforts are insufficient, but there are several solutions for this problem. Firstly, communities could implement a multipronged, collaborative approach to increase radon testing, similar to an approach employed by Iowa.25 This approach in Iowa involved establishing a coalition of stakeholders including the University of Iowa, the American Lung Association, local public health, lung cancer survivors, radon testers and mitigation specialists, among others. As a result, from 2009-2014, the number of radon tests completed in Iowa increased by 20%, and the number of mitigations completed by certified mitigators increased by 108%. Secondly, policy changes could help address the radon problem. Fourteen states in the U.S. have no laws regarding radon, radon testing and disclosure to and from homeowners. Twenty-three states (including Wisconsin) require disclosure of previous radon testing during real estate transaction, four states require radon testing in schools, and two states require radon mitigation in schools if radon is elevated.26 However, no states require homes to be tested for radon during a real estate transaction. Furthermore, there is a dearth of policies protecting renters from radon. Two states have laws that address the subject of radon in rental housing directly. Maine requires landlords to test for and disclose radon levels in their properties when requested by the tenant, and Illinois requires landlords to disclose known elevated radon levels.26 Given that one-third of the nation’s housing units are occupied by renters and that the risks of radon have traditionally have only been disclosed with home sale or transfer, renters are less likely to be aware of the risks of radon. Wisconsin could make significant progress in increasing the prevalence of testing for and mitigation of radon gas through a combination of the policy changes implemented in other states and community-based initiatives to raise awareness of the health risks and the effectiveness of mitigation. Lastly, physicians could address this problem by asking their patients about radon, ensuring that radon is emphasized in undergraduate and graduate medical education, and by distributing radon test kits in primary care clinics, which represents an intriguing area of future research.
This study has several limitations. The data are based on survey responses, which are subject to multiple biases. BRFSS and SHOW are carefully designed to be representative, whereas the landlord and school district surveys have more potential for bias. The wording of the radon question in SHOW (i.e. have you tested for radon in this home?) may pose limitations in estimating the prevalence of radon testing in all residential dwellings. For example, if the respondent focuses on the “you” in the question, they may have reported “no” if someone else did or coordinated the testing. This may explain way the estimate is lower. Also, only SHOW participants who reported having a basement in their home were asked about radon testing, which may affect the prevalence estimate. Response bias may have influenced the results of the school district and landlord surveys, as those school districts and landlords that have tested for and/or mitigated radon are more likely to respond and complete the survey. This would artificially increase our measured percentage of school districts and landlords that have tested for and/or mitigated radon. While we can speculate that many of the “unsure” responses about testing and mitigation probably indicate a lack of awareness of radon and therefore a lack of testing and/or mitigation, we could not categorize these as such.
In conclusion, these results demonstrate that current levels of radon testing and mitigation in residential homes, landlords, and school districts in the state of Wisconsin are inadequate. Implementation of innovative strategies will be required to improve awareness, mitigation, and testing of radon, which could help prevent about 500 unnecessary Wisconsin deaths every year.
Supplementary Material
ACKNOWLEDGEMENTS
The authors thank: Bill Field for helpful discussions; Colin Longhurst for assistance with power calculations; Xiao Zhang and Natalia Arroyo of the University of Wisconsin-Madison Cancer Prevention and Outcomes Data Shared Resource (C-POD) for critique of the landlord and school district surveys; Elizabeth Fracica for helpful discussions; and all of the landlords and school district administrators that participated in our surveys. The project described was supported by: the Clinical and Translational Science Award (CTSA) program, through the NIH National Center for Advancing Translational Sciences (NCATS), grant UL1TR000427; the University of Wisconsin Carbone Cancer Center Support Grant P30 CA014520. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
ABBREVIATIONS
- BRFSS
Behavioral Risk Factor Surveillance System
- CDC
Centers for Disease Control and Prevention
- EPA
Environmental Protection Agency
- SHOW
Survey of the Health of Wisconsin
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