Radon: A Killer Without a Conscience

The ‘Watras’ Incident

Pottstown, Pennsylvania, 1984. Stanley J. Watras, a construction engineer at the Limerick nuclear powerplant, sounds the alarm alerting all personnel that unsafe levels of radiation were present within the building. Mr. Watras was immediately examined by safety personnel in an effort to locate the source of the radiation. Even though Mr. Watras was covered in radioactive material, the source could not be located. Furthermore, no nuclear fuel was being stored in the nuclear plant during the incideht due to construction. Therefore, the radiation could not possibly be coming from the facility.

It was later discovered that the source of the radiation was actually Mr. Watras’ home; he had been radioactively-contaminated each time he went home, and had been carrying it with him to work. The amount of radon considered dangerous to humans by the Environmental Protection Agecy (EPA) is 4 pCi/L (picocuries per liter of air) or higher. The radiation at his home measured at 2,700 pCi/L, ~700 times the level considered safe (1). So, what exactly was the source of these alarmingly high radiation levels around Mr. Watras’ home? The answer: Radon Gas.

What is Radon?

Radon (Rn), is a naturally-occurring gas that is the byproduct of the normal decay of the elements uranium (U), radium (Ra), and thorium (Th) and is released into the air in different quantities depending on soil-type and the geology of an area. Igneous and metamorphic rocks, such as granite or black shales, and uranium ores are the primary source rocks of radon. According to Brian Redmond, professor of geology and chemistry in Wilkes University's Department of Environmental Engineering and Earth Sciences, the Watras’ home was located on a belt of uranium-rich rock known as the Reading Prong (2). In addition, the Marcellus Shale that provides much of the natural gas supply throughout Pennsylvania is also high in uranium. While radon typically does not pose a threat to humans under normal circumstances, higher concentrations of radon derived from rich radioactive sources, such as in the case of the ‘Watras’ Incident, can be dangerous.

According to the EPA, radon is one of the leading causes of lung cancer in both smokers and non-smokers, attributed to ~21,000 cases of lung cancer-associated deaths every year, second only to lung cancer deaths caused by smoking alone. Furthermore, the Centers for Disease Prevention and Control states that smokers who are exposed to unsafe levels of radon have a 10 times higher risk for lung cancer. It may be one of the greatest environmental health threats faced in the United States today. To make matters more complicated, it is colorless, odorless, and tasteless: A silent killer.

How it Spreads

While low levels of radon are present in the air supply daily, 1 in 15 homes are estimated to possess unsafe levels of radon (over 4 pCi/L) (3). It typically intrudes into homes  through cracks in walls, floors, and foundations with the highest concentrations of the gas typically found in basements and first-floors due to their proximity to the ground. Depending on the local geology of an area, radon may also dissolve into groundwater and be released into the air after being pumped from a well. Once inside the home, it can be further spread to the immediate area via air conditioning systems. How does it spread throughout the body? The radioactive radon particles attached to dust are then inhaled, leading to damage of the cell-lining that coats the lungs.

How is Radon Detected and Treated?

There is an effective means for detecting radon in the form of test kits. The most common method in determining if Radon is present is activated carbon testing, a technique that uses an activated charcoal canister as a proxy for radioactive exposure. A short-term test kit (2-4 days) or a long-term test (3-12 months for more accurate results) can be purchased for about $15.00 to $25.00 respectively, depending on the supplier.

A range of techniques can be used to mitigate radon exposure, such as active soil depressurization (ASD), a technique that pulls radon gas from beneath a foundation and exhausts it to the outside of a building using a fan. Additionally, caulking and sealing of foundation cracks and openings in conjunction with ASD can aid in the mitigation process.

Am I at Risk?

Most of the Gulf Coast, including the State of Texas, is characterized by the EPA as ‘low potential zones’ (less than 2 pCi/L) for radon overexposure, meaning that Houston is not a high-risk zone on average. A risk assessment map for Texas is shown below, and one for the entire USA can be found here:

Modified from the  EPA

Modified from the EPA

Despite being uncommon in some places, it is important to remember radon overexposure can happen even in low-risk zones and the risk increases depending whether you are a smoker or non-smoker.

Latitudes Environmental is a full-service consulting firm, practicing in indoor air quality and industrial hygiene.


1.      Palmer, Jani. Radon May Be Radioactive And Cause Cancer, But Can It Set Off Alarms In A Nuclear Power Plant? The EPA Blog (2012). Retrieved from https://blog.epa.gov/2012/01/10/radon-may-be-radioactive-and-cause-cancer-but-can-it-set-off-alarms-in-a-nuclear-power-plant/

2.      Rose, Jason. Have You Heard the Story of Stanley Watras? Active rain (2009). Retrieved from https://activerain.com/blogsview/1100259/have-you-heard-the-story-of-stanley-watras-

3.      A Citizen's Guide to Radon: The Guide to Protecting Yourself and Your Family from Radon. US EPA (2016). Retrieved from https://www.epa.gov/radon/citizens-guide-radon-guide-protecting-yourself-and-your-family-radon

4. EPA Map of Radon Zones including State Radon Information and Contacts. US EPA. Retrieved from https://www.epa.gov/radon/find-information-about-local-radon-zones-and-state-contact-information#radonmap

David Lewis