Rain and Radon
We’ve all heard that “April showers bring May flowers,” but can April showers also bring more rain and radon? Well…maybe. Here’s why.
Weather conditions such as rain, humidity, barometric pressure, and wind can affect radon that is measured within a home. Rain storms can both increase and decrease the amount of radon that is allowed to enter a home. However, in most cases, rain can temporarily increase radon gas within a home.
Radon is a naturally occurring gas that occurs from the breakdown of uranium in the soil around your home, office, or school building. It enters buildings through cracks and other openings in the foundation, such as sump holes or drains.
Weather Conditions Can Affect Your Radon Levels
Barometric Pressure
Barometric pressure, or atmospheric pressure, is the pressure within the earth’s atmosphere. This pressure consists of gas molecules in the air and is measured as the downward pressure exerted on the ground. Essentially, it is the force exerted on the earth’s surface by the weight of air. The more densely concentrated the molecules, or heavier the air, then the higher the pressure will be. Barometric pressure at higher elevations is much lower because there are less molecules pressing down on them from above.
Barometric Pressure and Radon
Weather fluctuations such as wind and temperature changes affect the barometric pressure. Rainfall occurs when there is low barometric pressure which is why weather forecasters use falling barometric pressure as a predictor of rain. This reduction in pressure on the earth’s surface can allow more radon gas to rise from the soil where it can move into homes through cracks in the foundation.
Also, the drop in barometric pressure during rainfall can change the air pressure within a home. If the air pressure in the home is lower than the air pressure outdoors, then the home acts like a vacuum and pulls in air and radon gas from the soil around your home.
Humidity and Radon
Humidity is the measurement of water vapor in the air. It is the highest when it rains.
According to the EPA, radon and radon decay products in the air can be captured in rain drops as they fall to the ground which temporarily increase radon. Also, rain saturates the the soil with water. This increased moisture displaces air in the soil hat can enable radon gas in the soil to follow the path of least resistance and be transported up to the surface and into a home or building.
Rain is frequently accompanied by high winds. Winds blowing against a side of a home with doors and windows can create positive pressure in the house that “pushes” the radon out. High winds hitting the side of a house without doors or windows can create negative pressure inside the home which then draws the radon into the home.
Testing For Radon During A Rain Storm
Rainfall does not affect radon in every home or building the same way, but it’s important to know that it can influence a test result to be abnormally high or low. The ANSI/AARST standards state that one should, “Avoid testing your home for radon during severe weather if the test is less than 72 hours.”
If it starts to rain or becomes windy while you are conducting a radon test, it doesn’t mean your test will be invalid. An alpha track radon test such as the Rapidos radon detector is less susceptible to humidity. A long-term test that runs for 91 days to a year such as the Radtrak provides the most accurate radon average and is the least susceptible to weather conditions.
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