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Radon in Colorado
These maps show estimates for radon levels in indoor air in Colorado counties based on three different sources.

Figure 1, adapted from the Environmental Protection Agency (EPA) and United States Geological Survey (USGS), shows radon potential in Colorado counties. Radon potential is defined as having an indoor air radon level over the EPA action limit of 4 picocuries per liter (pCi/L). Radon potential is determined based on a model that includes the bedrock geology, soil characteristics, construction types, aerial radiation measurements, literature review and indoor radon testing. Based on the assumption that all of these inputs remain fairly constant except for the availability of indoor radon testing results the original model was augmented with more robust and current data. The original 1218 samples taken from 48 of Colorado’s 64 counties were replaced with approximately 20,000 pre-mitigation samples collected from all 64 counties in 2011 and 2012.

Figures 2 shows the average concentration of indoor air radon for each county in Colorado based on results of radon tests that are voluntarily conducted and reported to the Colorado Department of Public Health and Environment (CDPHE) Radon Outreach Program. Some counties average radon value is below the predicted value (Figure 1). This is attributed to the fact that Figure 1 represents an inclusive model with five variables, including indoor radon test results, while Figure 2 is a summary of indoor radon test results only.

Figure 3 shows the percent of indoor air radon tests above the EPA action level of 4 pCi/L for each county in Colorado based on results of radon tests that are voluntarily conducted and reported to the Colorado Department of Public Health and Environment (CDPHE). The majority of counties had a high percentage of tests above the EPA action level.

Figure 4 shows Colorado residents’ awareness of radon as reported by the 2012 BRFSS survey results. More than 5,300 Colorado residents were asked “Do you know what radon is?” About 80% of whites participating in the survey knew what radon was, compared to less than 50% of blacks and Hispanics. Only 30% of those with less than a high school education were aware of radon risks, compared to 90% of college graduates.

Figure 5 shows Colorado residents’ responses to questions about the level of radon in their homes as reported by the 2012 Behavioral Risk Factor Surveillance System (BRFSS) telephone survey. The map indicates residents in seven counties were less likely than residents in other counties to report having a radon level above 4 pCi/L. But radon test results reported to CDPHE, shown in Figure 3, indicate a high percentage of tests above 4 pCi/L in most of those seven counties.

Table 1 shows data from over 140,000 home radon tests voluntarily conducted and reported to CDPHE from 2005 through 2012. Some of these data are mapped in Figures 2 and 3 above. This table provides details of the number of tests that were reported in each county during this time period. State-wide, almost half of all radon tests reported to the state exceed the mitigation level.

Figure 6 Smoking prevalence data shown here are aggregated from BRFSS data collected in the 2011 and 2012 survey. The smoking prevalence data for Colorado shows only two counties that have statistically higher rates of smoking (Adams and Fremont), but these data may be of value to local health professionals when considering individuals’ risk for lung cancer. If you have radon in your home and you smoke, your risk for lung cancer is significantly higher than it is from either smoking or being exposed to radon alone.

Figure 7 The data displayed here is a combination of Figures 1 and 7, and provide a more detailed look at radon potential across counties. In some cases, parts of counties actually have a higher radon potential than the average measures displayed in Figure 2. The data in this map could help an individual or public health professional more appropriately assess the risk associated with smoking and potential for radon exposure. The information below from the American Cancer Society and the United States Environmental Protection Agency (Tables 2a & b) illustrates the relationship between radon exposure, smoking and lung cancer.

Figure 1: Colorado map of radon potential

Figure 1, adapted from the Environmental Protection Agency (EPA) and United States Geological Survey (USGS), shows radon potential in Colorado counties. Radon potential is defined as having an indoor air radon level over the EPA action limit of 4 picocuries per liter (pCi/L). Radon potential is determined based on a model that includes the bedrock geology, soil characteristics, construction types, aerial radiation measurements, literature review and indoor radon testing. Based on the assumption that all of these inputs remain fairly constant except for the availability of indoor radon testing results the original model was augmented with more robust and current data. The original 1218 samples taken from 48 of Colorado’s 64 counties were replaced with approximately 20,000 pre-mitigation samples collected from all 64 counties in 2011 and 2012.

The original EPA model predicts average radon levels above the EPA action level of 4 pCi/L for all but 12 of the 64 counties in Colorado. Running the same model in 2013 using more robust data predicts average radon levels above the EPA action limit of 4 pCi/L for all of Colorado’s 64 counties. This means that every home in Colorado is at risk of having radon levels above the EPA action level and should be tested for radon.

*Action limit for indoor radon is 4 pCi/L

Figure 1

Source: Colorado Department of Public Health and Environment (CDPHE) Hazardous Materials and Waste Management Division (HMWMD) Radon Program, Colorado Environmental Public Health Tracking, and United States Geological Survey (USGS).


Figure 2: Average concentration of indoor radon by county, based on test results reported to CDPHE, 2005 – 2012.

Figure 2 shows the average concentration of indoor air radon for each county in Colorado based on results of radon tests that are voluntarily conducted and reported to the Colorado Department of Public Health and Environment (CDPHE) Radon Outreach Program. Some counties average radon value is below the predicted value (Figure 1). This is attributed to the fact that Figure 1 represents an inclusive model with five variables, including indoor radon test results, while Figure 2 is a summary of indoor radon test results only.

*Action limit for indoor radon is 4 pCi/L
Click to expand the Radon Map

Source: Colorado Department of Public Health and Environment (CDPHE) Hazardous Materials and Waste Management Division (HMWMD) Radon Program, and Colorado Environmental Public Health Tracking.


Figure 3: Percent of radon tests above 4 pCi/L by county, based on test results reported to CDPHE, 2005-2012.

Figure 3 shows the percent of indoor air radon tests above the EPA action level of 4 pCi/L for each county in Colorado based on results of radon tests that are voluntarily conducted and reported to the Colorado Department of Public Health and Environment (CDPHE). The majority of counties had a high percentage of tests above the EPA action level.

*Action limit for Indoor Radon is 4 pCi/L
Click to expand the Radon Map

Source: Colorado Department of Public Health and Environment (CDPHE) Hazardous Materials and Waste Management Division (HMWMD) Radon Program, and Colorado Environmental Public Health Tracking.


Figure 4: Radon awareness in Colorado residents

Figure 4 shows Colorado residents’ awareness of radon as reported by the 2012 BRFSS survey results. More than 5,300 Colorado residents were asked “Do you know what radon is?” About 80% of whites participating in the survey knew what radon was, compared to less than 50% of blacks and Hispanics. Only 30% of those with less than a high school education were aware of radon risks, compared to 90% of college graduates.


Figure 4
*Action limit for indoor radon is 4 pCi/L

Source: Colorado 2012 Behavioral Risk Factor Surveillance System (BRFSS), Health Statistics Section, Colorado Department of Public Health and Environment (CDPHE).


Figure 5: BRFSS survey responses – likelihood of residents to report a radon test result above 4 pCi/L compared to state average

Figure 5 shows Colorado residents’ responses to questions about the level of radon in their homes as reported by the 2012 Behavioral Risk Factor Surveillance System (BRFSS) telephone survey. The map indicates residents in seven counties were less likely than residents in other counties to report having a radon level above 4 pCi/L. But radon test results reported to CDPHE, shown in Figure 3, indicate a high percentage of tests above 4 pCi/L in most of those seven counties.

More than 5,300 Colorado residents were asked “Has your household air been tested for the presence of radon gas?” About 40% of them answered “yes” and were then asked “Were the radon levels in your household above 4 picocuries per liter?” Of those who had tested, about 20% said they had a radon test result above 4 pCi/L. However, 47% of home radon test results reported to CDPHE (Figure 6) were over the EPA action level.


Figure 5
*Action limit for indoor radon is 4 pCi/L

Source: Colorado 2012 Behavioral Risk Factor Surveillance System (BRFSS), Health Statistics Section, Colorado Department of Public Health and Environment (CDPHE).


Table 1: Radon test results reported to CDPHE by county, 2005-2012

Table 1 shows data from over 140,000 home radon tests voluntarily conducted and reported to CDPHE from 2005 through 2012. Some of these data are mapped in Figures 2 and 3 above. This table provides details of the number of tests that were reported in each county during this time period. State-wide, almost half of all radon tests reported to the state exceed the mitigation level.

About radon testing data:
All Colorado homeowners are encouraged to purchase an indoor air test kit, or hire a radon testing professional to find out if radon levels are high, but the decision about whether to test is left up to each homeowner. Individuals can use this coupon to get a radon test kit for $15. Radon test kits are sent to laboratories for analysis. Radon laboratories send the results back to the individual, and also voluntarily provide the results to the Colorado Department of Public Health and Environment (CDPHE) along with the zip code in which the test was done.

There are some limitations to the data:
  • Doesn’t allow us to compare radon levels in different areas of the state because testing is voluntary, so some areas report more tests than others and we don’t know if results are representative of an entire county or zip code. For example, some counties report thousands of tests in a year while others report less than one hundred. For this reason there isn’t enough information to compare radon levels.
  • Results don’t indicate if it was a first test or a test performed after radon mitigation steps have been taken. Often times an additional test is taken after mitigation is performed to make sure the mitigation was successful. These results are almost always lower and well below the EPA action limit of 4 pCi/L. Historically this information is not included and it is impossible to know how many houses are actually being tested, since one house may be tested multiple times. It is also not possible to know if lower test levels reflect radon mitigation efforts or lower levels of radon in that geographic area. Beginning in 2011 radon data reported to CDPHE includes post-mitigation indicators meaning that data can be removed from the data set prior to evaluation for summary measures. There is still no way to know, however, if one home is represented by multiple samples because the addresses are removed from the data provided to CDPHE to protect the privacy of the homeowner.
  • The only information available for all reported radon tests are year of test, test result, and the zip code in which the test was done. Because many zip codes cross county lines there is some uncertainty in assigning tests to individual counties where zip codes cross county boundaries. In these cases the test result is attributed equally to each county that it may represent.
Looking at radon test results by county
To estimate radon test results by county, CDPHE used Microsoft Access to create a table that contained all Colorado zip codes and the respective counties. This allowed each home radon test result to be attributed to a county.

In some cases a radon test result is attributed to multiple counties when the zip code associated to the test result falls in multiple counties.

This method does not establish exact radon metrics across the state. It does provide a snapshot of radon hazards across the state, including the occurrence of radon levels well in excess of the EPA action limit.


Table 1

Source: Colorado Department of Public Health and Environment (CDPHE) Hazardous Materials and Waste Management Division (HMWMD) Radon Program, and Colorado Environmental Public Health Tracking


Figure 6: Co-display of county level radon measures and smoking prevalence

Figure 6 shows smoking prevalence data shown here are aggregated from BRFSS data collected in the 2011 and 2012 survey. The smoking prevalence data for Colorado shows only two counties that have statistically higher rates of smoking (Adams and Fremont), but these data may be of value to local health professionals when considering individuals’ risk for lung cancer. If you have radon in your home and you smoke, your risk for lung cancer is significantly higher than it is from either smoking or being exposed to radon alone.


Figure 6
*Action limit for indoor radon is 4 pCi/L

Source: Colorado 2012 Behavioral Risk Factor Surveillance System (BRFSS), Health Statistics Section, Colorado Department of Public Health and Environment (CDPHE).


Figure 7: Co-display of radon potential provinces and smoking prevalence, 2011 - 2012

Figure 7 The data displayed here is a combination of Figures 1 and 7, and provide a more detailed look at radon potential across counties. In some cases, parts of counties actually have a higher radon potential than the average measures displayed in Figure 2. The data in this map could help an individual or public health professional more appropriately assess the risk associated with smoking and potential for radon exposure. The information below from the American Cancer Society and the United States Environmental Protection Agency (Tables 2a & b) illustrates the relationship between radon exposure, smoking and lung cancer.


Figure 7
*Action limit for indoor radon is 4 pCi/L

Source: Colorado 2012 Behavioral Risk Factor Surveillance System (BRFSS), Health Statistics Section, Colorado Department of Public Health and Environment (CDPHE).


Additional Information on Radon Exposure and Smoking

American Cancer Society

Cigarette smoking is by far the most common cause of lung cancer in the United States, but radon is the second leading cause. Scientists estimate that about 20,000 lung cancer deaths per year are related to radon.

Exposure to the combination of radon gas and cigarette smoke creates a greater risk for lung cancer than either factor alone. Most radon-related lung cancers occur among smokers. However, radon is also thought to cause a significant number of lung cancer deaths among non-smokers in the United States each year ( American Cancer Society ).

Your chances of getting lung cancer from radon depend mostly on:
  • How much radon is in your home
  • The amount of time you spend in your home
  • Whether you are a smoker or have ever smoked
    ( EPA Physician's Guide )



Table 2a: Radon Risk If You Smoke

Table 2b: Radon Risk If You Have Never Smoke

Source: Colorado Department of Public Health and Environment (CDPHE) Hazardous Materials and Waste Management Division (HMWMD) Radon Program, and Colorado Environmental Public Health Tracking

What is radon?
 
Radon is a colorless, odorless, radioactive gas that forms naturally in soil. Radon is produced when uranium in the soil breaks down.
 

Why is radon a concern?
 
Radon is known to cause lung cancer and it can seep into our homes and workplaces through cracks and openings in floors and crawlspaces. When this happens, radon becomes part of the air we breathe.
 

How to test your home for radon
 

How to test your home for radon
Perform a simple, short-term test in your home. You can do it yourself and it takes 48 to 96 hours to complete. You should keep windows closed 12 hours prior to testing your house.

A coupon for $15 test kits is available on the Colorado Department of Public Health and Environment (CDPHE) website. After testing, mail the test kit to the address provided; results will be mailed to you.

If radon levels in your home are high:
  • A mitigation system should be installed if the concentration of radon is more than 4 pCi/L. These systems should include sealing cracks and openings and installing PVC piping and a fan to remove radon gas, to prevent radon from entering your home. These systems usually cost between $800 and $1,500 in the Denver metro area. In other areas of Colorado they can cost more.
  • Find a National Environmental Health Association (NEHA) certified mitigation contractor in Colorado who can install a radon mitigation system.
 

Can radon make me sick?
 
When a person is exposed to radon over many years the exposure can increase the risk of lung cancer . Radon is the second-leading cause of lung cancer in the United States; only smoking causes more lung cancer. Radon is the leading cause of lung cancer in non-smokers.

Each year, about 20,000 deaths in the United States are attributed to radon-caused lung cancer. Risk of lung cancer from radon is almost 10 times higher for smokers compared to those who have never smoked. Smoking and radon together create a greater risk of lung cancer than either one alone.
 

Who is at risk?
 
  • Everyone exposed to radon over a long period of time is at risk for lung cancer.
  • Smokers are at higher risk of lung cancer. Exposure to a combination of smoking and radon creates a greater risk than either factor alone.
  • While some studies have reported that children are at greater risk than adults for certain types of cancer from radiation, currently there is no conclusive data that their radon risk is greater than adults.
  • In Colorado we have high levels of radon in our soils. ​ Data collected o​n​ indoor air radon levels indicates that most of the counties in Colorado have average levels greater than 4 picocuries per liter (pCi/L), which is the level at which EPA recommends radon mitigation. ​
 

How can the risk be reduced?
 
Test your house for radon:
A simple test you can do yourself will tell you if you need to take action to lower radon levels in your home. A coupon for $15 test kits is available on the CDPHE website. If the concentration of radon is more than 4 pCi/L you should take action to lower the radon levels in your home.

Don’t smoke:
Exposure to a combination of smoking and radon creates a greater risk of lung cancer than exposure to just smoking or just radon alone. The risk of the two together is greater than just adding up the risk from each one; they interact to make lung cancer even more likely.
 

How is radon tracked?
 

Radon testing is not required in Colorado, so the information available is limited. There are two sources of information used by COEPHT. One provides information from indoor radon tests that are conducted by homeowners. The other is BRFSS survey data that provides information on what Colorado residents report about radon tests in their homes.

About radon testing data:
All Colorado homeowners are encouraged to purchase an indoor air test kit to find out if radon levels are high, but the decision about whether to test is left up to each homeowner. Individuals can use this coupon from Colorado Department of Public Health and Environment (CDPHE) to get a radon test kit for $15. Radon test kits are sent to laboratories for analysis. Radon laboratories send the results back to the individual, and also voluntarily provide the results to CDPHE along with the zip code in which the test was done.

There are some limitations to the data:
  • It doesn’t allow us to compare radon levels in different areas of the state because testing is completely voluntary, so some areas report more tests than others and we don’t know if results are representative of an entire county or zip code. For example, some counties report thousands of tests in a year and others report only 2 or 3. So there isn’t enough information to compare radon levels.
  • Results don’t indicate if it was a first test or a test performed after radon mitigation steps have been taken to make sure the mitigation was successful. Because this information is not included it is impossible to know how many houses are actually being tested, since one house may be tested multiple times. It is also not possible to know if lower test levels reflect radon mitigation efforts or lower levels of radon in that geographic area.
  • While some studies have reported that children are at greater risk than adults for certain types of cancer from radiation, currently there is no conclusive data that their radon risk is greater than adults.
  • The only information available for all reported radon tests are year of test, test result, and the zip code in which the test was done. Because many zip codes cross county lines it is difficult to look at this data by county.
Looking at radon test results by county
To estimate radon test results by county, CDPHE used Microsoft Access to create a table that contained all Colorado zip codes and the respective counties. This allowed each home radon test result to be attributed to a county.

Some duplication occurred as several zip codes cross county lines. When a zip code overlapped counties, the value for that zip code was applied to each county.

This method does not establish exact radon metrics across the state. It does provide a snapshot of radon hazards across the state, including the occurrence of radon levels well in excess of the EPA action limit.

About BRFSS survey:
The Behavioral Risk Factor Surveillance System (BRFSS) is an ongoing national telephone survey sponsored by CDC to monitor lifestyles, behaviors and awareness related to leading causes of illness, injury and death. In Colorado, over 1,000 adult residents complete the survey each month. In 2009 these questions about radon were included in the Colorado survey:
  • Do you know what radon is?
  • Has your household air been tested for radon?
  • Was the radon level above 4 picocuries per liter (pCi/L)?
 



Video: Radon the Invisible Killer
Source: Colorado Public Health and Environment
Running Time: (30:00)
Release Date: 01/11/2011

Video: Radon the Invisible Killer (Spanish Subtitles)
Health Watch No.93: Home is Where the Health is? Exploring Healthy Housing in Colorado
Source: Colorado Public Health and Environment - Health Statistics
Release Date: 03/2014
Click HERE to download the Health Watch
 
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