When buying a home in New Jersey, you’ll encounter the term “radon” during the home inspection process. Radon testing is a crucial step in ensuring your new home is safe and healthy for your family. Let’s break down everything first-time buyers need to know about radon, radon testing, radon mitigation, and long-term radon monitoring.

What is Radon?

Radon is a naturally occurring, colorless, odorless and tasteless radioactive gas. It is produced from the decay of uranium found in soil, rock and water. Radon can seep into homes through cracks in the foundation, construction joints, and gaps around pipes.

Exposure to high levels of radon is the second leading cause of lung cancer in the United States, according to the Environmental Protection Agency (EPA). Since radon levels vary widely from one location to another, testing your potential home is essential.

Radon Testing During Home Inspections

In New Jersey, radon testing is an important part of the home inspection process when buying a house. A licensed radon measurement technician must conduct the test, as radon measurement is regulated by the State. However, typically the inspector you hire to perform your General Home Inspection (read about the GHI here: Inspections) will also be a licensed radon technician, allowing him to conduct a radon test at the same time as he completes the GHI.

Conducting a radon test involves placing a radon test kit in the lowest livable area of the home, such as a basement. One of the most common types of radon test kit consists of an open-face charcoal canister. The canister contains activated charcoal, which has a large surface area and porous structure, allowing it to effectively adsorb radon gas. When the canister is placed in a home, radon from the surrounding air diffuses into the charcoal and binds to its surface. The canister must be left in the home for generally 48 to 96 hours. During this time, it continuously adsorbs radon from the air (which is why windows and doors should remain closed as much as possible to ensure accurate results). Once the exposure period is complete, the radon technician returns to the home to pick up the canister, which is sealed to prevent any further adsorption of radon. It is then sent to a certified laboratory for analysis.

At the lab, the charcoal is analyzed for the amount of radon it has adsorbed. Radon decays into radioactive particles, and the lab uses specialized equipment to measure the levels of radiation emitted from the charcoal. This data is then used to calculate the average radon concentration in the air during the test period, reported in picocuries per liter (pCi/L).

Understanding Radon Levels and the 4.0 Threshold

Radon levels are measured in picocuries per liter of air (pCi/L). The EPA has established a threshold of 4.0 pCi/L as the action level for radon. That is, if the radon test results show radon levels at or above 4.0 pCi/L, the EPA recommends that a radon mitigation system be installed in the home to reduce these levels to a safer range.

In New Jersey home purchases and sales, the form Contract that is the basis for nearly every transaction includes a provision outlining the testing and mitigating of radon.

What is a Radon Mitigation System?

A radon mitigation system is designed to reduce radon levels inside a home. The most common type of system is a sub-slab depressurization system, which includes:

• PVC Piping: Installed beneath the foundation to collect radon gas.
• Vent Fan: Located outside the home or in an attic to pull radon out of the home through the PVC Piping and vent it safely to the exterior above the roofline.

How a Radon Mitigation System Works

1. Detection and Assessment
   Before installing a radon mitigation system, radon levels are measured using testing kits, typically administered by a professional radon technician and oftentimes during the course of a home inspection for a home purchase transaction. Radon is typically measured in “picocuries per liter” (pCi/L). Levels of 4.0 pCi/L or higher are considered hazardous by the U.S. Environmental Protection Agency (EPA).

2. System Components
   The primary goal of a radon mitigation system is to prevent radon gas from entering the home and to vent any accumulated radon outdoors. The most common system used is active soil depressurization (ASD). Here are the main components:

   • PVC piping: Runs from beneath the foundation of the building to above the roofline.
   • Radon fan: Installed in the pipe, often in the attic, garage, or outside, to create suction.
   • Sealing: Cracks in the foundation, floors, or walls are sealed to minimize radon entry points.

3. Active Soil Depressurization Process

   • A suction point is created by drilling a hole into the foundation (e.g., basement floor or slab).
   • The radon fan continuously draws air (and radon gas) from the soil beneath the home.
   • The gas is transported through the PVC piping and released into the atmosphere, far enough away from windows and other openings to prevent re-entry.

4. Sub-Slab or Sub-Membrane Depressurization
   For homes with different foundations, variations of ASD may be used:

   • Sub-slab depressurization: Used for homes with slab-on-grade foundations.
   • Sub-membrane depressurization: Used for crawl spaces, where a plastic sheet is laid over the soil and sealed, and radon is vented from beneath the membrane.

5. Passive Radon Systems
   Some homes are built with passive radon systems, which rely on natural airflow and pressure differences to vent radon gas without a fan. However, passive systems are less effective, and adding a fan can often improve performance.

6. Post-Installation Testing
   After the system is installed, radon levels are retested to ensure they are below the recommended safe threshold.

This system prevents radon from accumulating in the home and significantly lowers radon levels, often well below the 4.0 pCi/L threshold.

Staying Safe: Long-Term Radon Monitoring

After installation of a radon mitigation system, or even if your radon levels without a mitigation system are below the threshold, it’s important to monitor your home’s radon levels regularly. Radon levels can fluctuate due to changes in weather, home renovations, or natural shifts in the soil.

For example, radon levels in many homes tend to increase during the winter, due factors such as the “stack effect” (the movement of air into and out of a building through openings like chimneys, vents, and unsealed cracks, caused by differences in temperature between the inside and outside of the building), reduced ventilation (doors and windows tends to remain closed in winter), and the frozen ground. However, this isn’t a hard and fast rule. Data has shown that in 25% of homes, radon can even be at its highest during summer periods.

Due to the potential unpredictability of radon levels in homes, one of the best ways to keep track of radon levels is by using a continuous radon monitor (CRM). These devices provide real-time, ongoing radon readings and can alert you if levels rise unexpectedly. Some CRMs even come with smartphone apps for easy tracking and reporting.  

Key Takeaways for First-Time Home Buyers

1. Radon is a common issue in New Jersey homes and can pose serious health risks.
2. Radon testing is a standard part of the home inspection process.
3. If radon levels exceed 4.0 pCi/L, a mitigation system is needed.
4. A radon mitigation system effectively reduces radon to levels below the 4.0 threshold.

By understanding radon and its mitigation, you can confidently navigate the home-buying process and ensure a safe home environment for you and your family.