What is radon, and why does the Environmental Protection Agency (EPA) recommend testing for radon when completing a home purchase? This article explains radon testing, mitigation and everything else California real estate agents need to know about this dangerous substance found in homes across the state.

Radon 101

Radon is a naturally occurring substance, made when the chemical element radium decays. Since radium is found in earth, rock and water around the world, radon is virtually everywhere. It becomes dangerous when it seeps into the home through small cracks in the walls or foundation and is not vented properly.

Radon is measured by picocuries per liter or pCi/L. There is no “safe” level of radon concentration, but mitigation is highly recommended for any space with a radon level above 4.0 pCi/L. For spaces with radon levels between 2.0 and 4.0 pCi/L, mitigation is up to the discretion of the property owner.

Behind smoking, radon is the leading cause of lung cancer, responsible for over 20,000 deaths each year, making radon a bigger killer than drunk driving. For example, living in a home where radon levels exceed the recommended limits is equivalent to receiving hundreds of chest x-rays a year. Radiation levels in a home like this can be higher than is allowed in nuclear facilities, according to Radon Awareness.

In California, high levels of radon have been identified in all corners of the state. But, generally speaking, the highest levels of radon are found in Santa Barbara and Ventura Counties. The average home in these counties has radon levels above the danger limit of 4 pCi/L, according to the EPA.

Central California shows a moderate risk of high radon levels, while most parts of Southern and Northern California are areas less likely to have high levels. Still, high radon levels may be found in any part of the state. For instance, pockets of high radon can be found in cities as diverse as Encino, Visalia and Monterey. Further, radon is found in homes, commercial spaces, schools and any type of building. Therefore, testing is important everywhere.

Radon testing

Radon testing is inexpensive and easy.

It’s recommended that radon testing is performed before purchasing a home. Homeowners serious about keeping their home safe from high radon levels can re-test every five years and each time a major renovation occurs.

There are two types of radon tests:

  • short-term tests, performed by the homeowner, using a kit usually purchased for $10-$15 at a local hardware store or online; and
  • long-term tests, performed by a certified radon tester.

Radon levels tend to be highest on the bottom level of the home, closest to where the foundation meets soil. Therefore, the testing equipment needs to be placed in this part of the home. Ideally, the room where the testing equipment is placed will remain shut, without ventilation, for the duration of the test.

The short-term test takes a few minutes, and provides a less accurate figure than the long-term test, which takes a couple of days. Long-term tests performed by a certified radon tester are always recommended for homebuyers, and can be ordered at the same time as the home inspection. In fact, many home inspectors are also certified to test for radon.

Homeowners with a well can also test their water for radon levels with a radon water testing kit.

Editor’s note — Free radon test kits are often provided through the California Department of Public Health (CDPH). Check the CDPH website for more information.

Radon mitigation

Since radon is a naturally occurring substance, it can’t be fully mitigated. Further, no level of radon is considered “safe.” But radon levels can be decreased below dangerous levels through professional mitigation or remediation.

Mitigation works by installing a ventilation system that brings the radon level in the home closer to outdoor levels. Most mitigation companies will offer some sort of guarantee. For instance, they may guarantee re-testing will show radon levels below 2.0 pCi/L.

The cost for radon mitigation is no small thing. Depending on the layout of the property and the levels, a system can cost anywhere from $1,000-$5,000. Homeowners can contact several companies for quotes.

An individual providing radon testing or mitigation needs to be certified by either:

  • the National Radon Proficiency Program (NRPP); or
  • the National Radon Safety Board (NRSB).

Locate a certified radon mitigation specialist at the CDPH website, here.

Read more about radon mitigation at the EPA’s Consumer’s Guide to Radon Reduction.

Advice for real estate agents

While laws vary from state-to-state, no rules currently exist requiring California real estate agents to provide radon information to clients during a home sale. However, knowledge is key to setting agents apart from the crowd. Plus, it could save your client’s life.

For homebuyers and sellers alike, the EPA recommends a radon test whenever purchasing a home. Consider it standard practice, just like a regular home inspection.

Radon can also be an issue for new construction. However, some builders choose to use radon-resistant construction materials and methods to ensure lower levels of radon in the home. Agents can instruct their homebuyer clients to ask the builder whether any such radon-reducing methods were employed in the construction of their new home.

When sellers already have a radon system installed, consider this a value-adding device. Still, the presence of a radon mitigation system may scare off some homebuyers. It’s important to inform hesitant homebuyers both about the dangers of radon and the benefits of a radon mitigation system. After all, a pre-existing system means the seller has fixed the problem and the homebuyer won’t have to deal with it, aside from re-testing at regular intervals.

When a seller is aware of high radon levels and they have not installed a mitigation system, they need to disclose this information to the homebuyer via the Transfer Disclosure Statement. [See RPI Form 304]

Real estate agents can become familiar with the EPA’s publication, The Home Buyer’s and Seller’s Guide to Radon. They can also send this to clients seeking more information on radon.