Radon Control in New Home Construction:

Developments in State Policy



According to the U.S. Environmental Protection Agency (EPA), indoor radon is the second leading cause of lung cancer in the United States and the leading cause of lung cancer among non-smokers. Indoor radon exposure is responsible for about 21,000 lung cancer deaths in the U.S. each year. See https://www.epa.gov/radon/health-risk-radon.

Radon is a radioactive gas found in soil and rock in all parts of the United States. The concentration of radon in indoor air is affected by the way we design and construct houses and other buildings. EPA has established an “action level” of 4 picoCuries/liter (pCi/L) — the level at which a building owner should take action to reduce radon in the indoor air. Because there is no known safe level of exposure to radon, EPA also recommends that Americans consider fixing their home for radon levels between 2 pCi/L and 4 pCi/L.

The EPA Map of Radon Zones shows the radon potential for each county in the nation. Zone 1 counties have the highest potential radon levels, with predicted average indoor radon screening levels greater than 4 pCi/L, while predicted average radon levels are 2-4 pCi/L in Zone 2 counties, and under 2 pCi/L in Zone 3 counties. Although the map shows predicted average radon levels, elevated radon levels have been found in every state and can be found in any area. The only way to know the radon level in a particular home is to test the home for radon.

When a new home is built, radon control techniques (also referred to as radon-resistant new construction) can be used to help keep radon from entering the home. See U.S. EPA, Radon-Resistant Construction Basics and Techniques for a description of the key elements of a radon control system and links to other technical resources

Given the potential limitations of a passive (non fan-powered) system, installing such a system does not ensure radon levels under 4 pCi/L. EPA’s Building Radon Out further recommends that “[t]he home should be tested after occupancy and the passive system should be activated [fan powered] if post-occupancy testing reveals radon levels at or above 4pCi/L.” See Building Radon Out at 30.

EPA also recently developed voluntary guidance addressing radon and many other indoor air quality issues in new home construction. The guidance, known as Indoor airPLUS, calls on builders of new homes in Zone 1 areas to use radon control techniques and to provide home owners in Zones 1 and 2 with radon testing kits and instructions for their use.

Certain non-governmental organizations have developed consensus-based, technical standards for radon control techniques in new home construction. For example, the International Residential Code (IRC), a model building code developed by the International Code Council, contains a radon control standard that calls for a passive (no fan) sub-slab or sub-membrane depressurization system to be installed in homes located in Zone 1 areas. Because the IRC standard is included as an optional appendix (“Appendix F”) jurisdictions that adopt the IRC as part of their building code must explicitly include Appendix F in order to establish the IRC’s radon control standard.

Another third-party standard is ANSI/AARST CCAH—2013 (also known as "RRNC 2.0 Reducing Radon in New Construction of 1 & 2 Family Dwellings and Townhouses"), developed by the American Association of Radon Scientists and Technologists (AARST) and approved by the American National Standards Institute (ANSI). RRNC.2.0 is a “code ready” standard that provides minimum requirements for rough-in of a mitigation system and activation of the mitigation system, if required, in newly constructed dwelling units. The standards also requires provision of at least one long-term radon test kit to occupants of each dwelling unit.


State Policies

State and local governments can play an important role in reducing the risks from radon exposure. In addition to providing education and information to builders and consumers, they can enact policies to help ensure that homes are built with radon control techniques. These policies can reference an existing radon control standard, or they can modify and adapt existing standards and guidance.

One important policy opportunity for protecting public health is to include radon control requirements in residential building codes— both local building codes and statewide building codes that are mandatory at the local level. The following states and the District of Columbia have incorporated such mandatory radon control requirements for new home construction into their residential building codes. Click on the links below for brief summaries of these policies.

States can also include radon control standards in their model state building codes. For example, the state building codes in Florida and Virginia incorporate radon control standards that must be applied if a local jurisdiction chooses to adopt a radon control standard at all. A 2017 Utah law amending the state residential code established that “when passive radon controls or portions thereof are voluntarily installed, the voluntary installation shall comply with Appendix F of the IRC.”

There are many more states that have state-wide residential building codes that can benefit from policies to control radon in new construction. Watch for updates to this page as new policies are established.


Last Updated: November 2019

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