Call us: (203) 272-3600

What Factors Impact Accurate Radon Test Results?

Radon Testing Kit

Radon is a naturally occurring gas formed from a breakdown of uranium and found in soil, water, and rocks. It is a radioactive gas that is the second leading cause of lung cancer in the United States, killing approximately 21,000 people per year. Routine inspections of radon levels in your home are an excellent idea, especially before purchasing a new property. However, you need to understand that outside factors can affect radon test results if performed at the wrong time. What are some of those factors?

Various factors impact radon test results, including:

  • High Winds
  • Barometric Pressure
  • Temperature
  • Precipitation
  • Home Construction

Performing a radon test without accounting for these factors can give inspectors false positives or negatives. It may sound confusing at first.

To learn more about the different ways these factors can affect your test results, read on!

High Winds

High winds can affect your home's radon levels in two ways, by either increasing or decreasing the levels. Which direction your levels go depends on how the winds hit your home.

When high winds hit your home on a side with the most doors and windows, it creates positive indoor pressure. Positive indoor pressure pushes radon out of your home, effectively dropping the levels.

Conversely, when high winds hit your home on a side with the least windows and doors, it creates negative indoor pressure. Negative pressure within your house will draw radon from the soil below into the building. With more radon entering the house, it raises the levels temporarily.

Barometric Pressure

As with high winds, barometric pressure can change the internal radon readings in your home. According to a Nevada Bureau of Mines and Geology Study, a decrease in barometric pressure can increase radon levels.

The barometric pressure acts as a retaining wall, keeping the radon trapped within the soil under your home. As the pressure decreases, the wall becomes weaker, and radon can seep out into surrounding areas. Radon can leak into your home through microscopic cracks in the foundation. As the barometric pressure can vary hourly, inspection groups will need to note the pressure during the inspection.


Outside temperature can affect your radon levels. During the cold winter months, radon levels increase because of poor ventilation. Radon levels are lower when you can open your windows and allow outside air to circulate throughout your home. When the mercury dips, it is less likely that you will open the windows and doors instead of keeping things shut up tight to hold on to heat.

During the spring and summer months, you don't close your home tight. With the increased ventilation, radon levels decrease significantly. Despite this benefit, it is best to get your home tested for radon during the cooler months. The results give you an idea of the worst-case scenario. This can help you determine how to combat the issue best. 


Rain and humidity can influence the radon levels in your home. Light rain is not likely to cause a change. However, heavier rain might raise the internal levels slightly.

Like with colder weather, when a heavy rain comes through, most people close up their homes. Heavy rain is usually accompanied by strong winds, which may come from a direction where there aren't several windows or doors. The negative pressure caused by the wind and closing the home is ideal for raising the levels inside.

According to the EPA, “rain, snow, and sleet” can capture radon in the air and pull it to the ground. This action causes the radon levels in the soil to increase. Increased soil levels can seep into your home.

On the flip side, frozen precipitation such as ice and snow may actually lower your home's radon level. As with higher barometric pressure, ice and snow create a barrier that keeps radon in the soil instead of in your home.

Home Construction

Home construction can play a part in how much radon is in your home. Many new homes are built to be energy efficient. They carefully work to seal your house from the outside world to make it easier to heat and cool. Windows have tight seals, and everything is buttoned down to keep heat in during the winter and out during the summer.

Being tightly close causes a problem with radon levels. The EPA notes that unless the new homes are built to the Reducing Radon in New Construction (RRNC) building code, they will have a much higher level. However, there is no guarantee that homes built to RRNC code will be completely radon-safe.

Older homes may still have radon level issues, depending on the location and construction. However, these houses were not built to be energy efficient like newer construction. As a result, there may be better ventilation to allow radon to push out of the home.


Many factors can give either a false negative or a false positive when conducting a radon test. High winds, barometric pressures, temperature, rain, and your home's construction all play a role in radon readings.