Radon

Radon is the second leading cause of lung cancer overall, and the leading cause among people who do not smoke. Many households in Maine have unsafe levels of radon. The radon data on the MaineTracking Network can help users understand what parts of the state may be at higher risk for radon in air, as well as areas where testing rates are low. Test result data, combined with survey data, help communities encourage homeowners and property owners to test their homes for radon.

What data are available?

Radon Testing and Treatment Behavior
Radon in Air Test Results

Radon Testing Behavior

These displays present information on the percentage of adults ages 18 and older who tested their homes for radon as reported through the Behavioral Risk Factor Surveillance System, a telephone survey. Data is based on a yes response to: "Has your household air been tested for the presence of radon gas?" (Radon Test). If so, "Were the radon levels in your household above normal?" (Levels Above Normal). And if above normal, "Did the radon levels get reduced/fixed?" (Levels Reduced).

Radon Testing (35%), Levels Above Normal (16%), and Levels Reduced (73%). Results for 2021.

Radon in Air Test Results

These displays present information on radon in air testing data sent to the Maine CDC Radiation Control Program. Maine state law requires the testing of rental properties and encourages testing of all properties. The Environmental Protection Agency recommends that homes testing at or above 4 picocuries per liter (pCi/L) take action to reduce exposure levels, and that homes testing between 2 pCi/L and 4 pCi/L consider taking action.

Town-level Data:	County Comparison Maps:

Radon Tables

Create a custom table of data about radon testing behavior and radon test results. The Environmental Protection Agency recommends that homes testing at or above 4 pCi/L take action to reduce exposure levels, and that homes testing between 2 pCi/L and 4 pCi/L consider taking action.

Measure Definitions

Radon Testing Behavior
- Data represent the estimated percent of Maine adults (age 18+) who have tested their household air for radon, had a radon result above normal, and had radon levels reduced, as reported by the Behavioral Risk Factor Surveillance System (BRFSS), a randomized telephone survey.

Radon in Air Test Results
- Data represent households tested for radon in air, summarized by geographic area (State, County, Town), and for rental and non-rental dwellings. Every distinct street address, or street address with apartment unit, is counted as one household. Radon test data are sent to the Maine CDC Radiation Control Program by service providers including laboratories, contractors and mitigators. Landlords also report test data for rental properties.
- In order to better represent the potential hazard found in tested households, tests conducted with mitigation present are excluded from the data.
- Radon is measured in radiation units of picocuries per liter, or pCi/L. Percentages of households at or above 2 or 4 pCi/L are displayed. The Environmental Protection Agency recommends that homes testing at or above 4 pCi/L take action to reduce exposure levels, and that homes testing between 2 pCi/L and 4 pCi/L consider taking action.
- Maximum , median, and 95th percentile measures:
  - The maximum level is the highest test result in the dataset measured in a given geographic area.
  - The median is the contaminant level in a given geographic area that represents a middle value, for which about half (50%) of the test results in the dataset for that area are higher, and half (50%) are lower. For towns with less than 10 households tested, this calculation is considered unstable, and results are not displayed.
  - The 95th percentile is the contaminant level in a given geographic area for which 5% of the test results in the dataset for that area are higher, and 95% are lower. For towns with less than 10 households tested, this calculation is considered unstable, and results are not displayed.

Data Limitations

Radon Testing Behavior
- Maine adults who are institutionalized, do not have a phone, or are unable to communicate are not represented.
- Statistical weights are used to calculate prevalence estimates in order to be more representative of the general adult population in Maine and to adjust for non-response, though weighting methods are not perfect in accomplishing this. In 2015, weighting methodology changed to include cell phone and landline respondents. Changes in prevalence estimates may be partially related to changes in weighting practices.
Radon in Air Test Results
- Radon test data only include results that have been submitted to the Radiation Control Program. Test results conducted before detailed reporting was required are not available. Summarized test results are primarily (97%) from 2013 through mid-2019.
- Test data results are not representative of all homes. Maine law only requires testing of rental properties. Data for non-rentals may be subject to bias, as results are based on homeowners who decide to test.
- Test data measures are not computed for all households combined (rental plus non-rental households). Since only rental properties are required to be tested for radon, rental properties would be over-represented in an "all households" measure.
- Test data assigned a status of "rental" only includes test results submitted by a landlord. If a laboratory submits test results for a rental property, instead of a landlord, it would be categorized as "non-rental" by default. Households are categorized as "rental" if any test was ever submitted by a landlord.

Environmental Public Health