What is Radon?

We have covered a solid amount of radon related topics so far. Such as knowing how and when to test, what material is under your slab and when a crawlspace encapsulation is necessary. I realize I am yet to cover the basics of radon!

Well, here it is!

What is Radon Gas?

Radon is a naturally occurring radioactive gas that is odorless, colorless, and tasteless. It is a byproduct of uranium decay, a common element found in soil and rock. The EPA attributes about 21,000 lung cancer deaths per year to radon, making it the second leading cause to lung cancer deaths after smoking. While radon is naturally occurring, the lung cancer risk it carries makes it a significant threat to human health. Especially when it accumulates in enclosed spaces, such as homes, office buildings or schools.

Let’s jump into the various aspects of radon, including its health risks, how it enters houses, methods of detection, and the importance of professional mitigation.

Historical Perspective

Radon’s discovery dates back to the late 19th century when scientists were exploring the properties of radioactive elements. In 1899, German physicist Friedrich Ernst Dorn identified a radioactive gas emitted from radium and named it "radon." As more research was conducted, scientists began to understand that radon was a decay product of uranium. However, it wasn't until the latter half of the 20th century that concerns about radon's health risks began to emerge.

Health Risks of Radon

Radon is serious business because of its potential health risks. Radon gas decays into radioactive particles called radon progeny, which can be inhaled. When these particles break down further, they release alpha particles that can damage lung tissue and increase the risk of lung cancer. Prolonged exposure to elevated levels of radon can significantly increase the risk of developing lung cancer over time. Smokers are at an even higher health risk from radon. The combination of radon gas and tobacco smoke can significantly amplify the potential for lung cancer. According to the World Health Organization (WHO) and the Environmental Protection Agency (EPA), the synergistic effects of smoking and radon exposure create a dangerous combination that dramatically increases the likelihood of developing lung cancer. In fact, WHO estimates that radon is responsible for about 10% of lung cancer cases worldwide, and this risk is particularly pronounced among smokers. The carcinogens present in tobacco smoke damage lung tissue, making it more susceptible to the harmful effects of radon.

What Causes Radon

Radon is a natural byproduct of the decay of uranium. Uranium is commonly found in soil and bedrock, especially throughout Tennessee (see radon zone map below). As uranium breaks down over time, it releases radon gas into the surrounding environment. This gas is trying to reach the atmosphere, traveling through pathways in the ground until it can escape. So, when we build a structure over the ground, such as a house or office building, the gas can seep into the building. Understanding the factors that contribute to radon's presence in homes is crucial for effective mitigation strategies.

Prevalence in Tennessee and Davidson County

Radon is a concern that extends across various regions, including Tennessee. The Environmental Protection Agency (EPA) has created radon zone maps to illustrate areas with different radon risk levels. Tennessee, as a whole, has pockets of moderate to high radon potential. Specifically, Davidson County, situated within EPA Zone 1, is characterized by the highest potential for elevated radon levels. Don’t sleep on Zone 2, though. Even though the average of a particular region may have average levels between 2-4pCi/L, that doesn’t mean that buildings are guaranteed to test within that range. Some will test well above the EPA action level of 4pCi/L.

Tennessee Radon Zone Map

How Does Radon Accumulate?

Once radon infiltrates a building, it can accumulate to dangerous levels, especially in poorly ventilated or enclosed spaces, or even new builds where the building envelope is extremely tight. This accumulation occurs due to a combination of factors, including the rate of radon emissions from the soil, the building's ventilation characteristics, and the radon's half-life. Radon's half-life is approximately 3.8 days, which means that half of the radon atoms will decay every 3.8 days. This might suggest that radon levels would continuously increase, but a balance is achieved due to the constant decay and replenishment from the soil. This balance leads to an average radon concentration that remains relatively steady over time. However, radon levels can be affected by seasonal change, precipitation, and changes in barometric pressure. Read up more on the seasonality of radon levels here!

The Stack Effect

While radon can be influenced by a variety of different factors, one of the more important phenomena to consider is the "stack effect." The stack effect, or the chimney effect, plays a significant role in how radon gas enters houses, particularly in taller buildings or those with multiple stories.

Understanding the Stack Effect:

The stack effect is a natural occurrence driven by temperature and pressure differences between the indoor and outdoor environments. In cold weather, the warm air inside a building rises and creates a pressure difference between the top and bottom of the structure. This pressure difference can lead to the infiltration of outdoor air into the lower parts of the building to balance the pressure. Conversely, in warmer weather, the effect can reverse, with cooler indoor air sinking and warm air escaping through upper levels.

Impact on Radon Infiltration:

The stack effect can have a significant impact on the infiltration of radon gas into homes. As warm indoor air rises, it creates a negative pressure in the lower levels of the building. This negative pressure can draw soil gases, including radon, into the building through openings such as cracks in the foundation, gaps around pipes, and sump pits. The taller the builder, the more pronounced the stack effect becomes, which can lead to pretty high radon levels.

Mitigation in Taller Buildings:

Taller buildings are particularly susceptible to increased radon levels due to the stack effect. Proper building design and ventilation systems are crucial in mitigating this effect. Incorporating dedicated radon-resistant construction techniques, such as using vapor barriers and sealing foundation cracks, and installing passive sub-slab ventilation pipes (which can later be activated; more on passive systems here) can help reduce the entry points for radon.

What is Radon Testing?

Radon testing is the process of monitoring the air until enough data has been collected to produce an average radon concentration. There’s lots of ways to get testing done. You can get a radon testing kit from Home Depot or Lowe’s, purchase a digital monitor, or hire a professional to perform the service. Short-term tests provide a snapshot of radon levels over a few days, while long-term tests offer a more accurate assessment over several months. You can read more on radon testing here!

How to Deal With Radon

If you find that your home has elevated levels of radon, it’s important to handle it quickly in order to mitigate the health risk. As we have discussed, radon exposure of longer periods of time increases the risk of developing lung cancer, even in non-smokers. When calling companies for quotes, be sure to make sure they are NRPP certified. Mitigation techniques can vary from situation to situation. However, more often than not the main technique used should be sub-slab depressurization, where a system of pipes and fans is installed to draw radon gas from the soil and expel it safely into the outdoor air.

Always Call The Radon Guys First!

We have mitigated thousands of homes, multifamily dwellings, and commercial buildings! Radon can seem like a difficult beast to concur, but through careful planning, diagnostics, and testing any house’s radon levels can be brought down to safe levels!