Does Rain Make Radon Worse? Interesting Facts

Rain rehydrates and replenishes our rivers and waterways and is necessary for all living things. But does rain make radon worse?

Rain makes radon worse by causing pressure changes in the atmosphere and increasing the density in the soil causing natural gasses to expand. To put it another way, the air has to go somewhere, and the changes in the atmosphere create more pressure and less space for it to do so.

Increased soil moisture raises radon concentrations by 10–20%. So yes, rain can increase radon levels in homes.

Does Rain Make Radon Worse? Interesting Facts
Rain is refreshing, but how does it affect radon?

Radon is a radioactive gas that seeps up from the soil and enters structures through cracks in the foundation or windows.

During weather patterns that cause radon to move from high concentrations in the soil into a house, radon concentrations indoors may increase significantly for a few days or weeks.

In most cases, radon levels will decrease again when weather conditions change.

Rain can increase the radon level indoors by stirring radon progeny that has settled on the ground around windows or doors, or inside crawl spaces or basements, into the air.

The radon progeny are then pulled back into homes when interior air pressure is greater than outdoor air pressure. This means radon progeny are brought inside as radon levels decrease outside.

The radon level indoors may increase for a few days or weeks until the radon progeny settles back to the ground again.

What Time of Day is Radon Highest?

Knowing what time of day radon is highest will help you take the proper precautions and allow your family to breathe easier. What time of day is radon highest?

Radon concentrations are generally higher during the early morning and late afternoon. Radon levels usually rise to their highest levels between 10:00 pm and 4:00 am. This is known as the “radon peak” and is when the windows and doors in your home are closed.

During times of the day when radon is the highest, you can take steps to help reduce indoor radon levels by opening all of your windows and exterior doors for at least 30 minutes.

Then close your windows and doors to prevent any further increase in radon levels.

Is Radon Worse in Winter or Summer

Radon levels naturally fluctuate depending on what time of day it is, as well as the season and weather patterns. So is radon worse in winter or summer?

Radon is worse in the winter when houses tend to be well-insulated and homes become relatively air-tight, making it more likely for radon to accumulate. Radon levels usually start to rise in the fall when temperatures drop with shorter daylight hours.

Radon levels vary, but they are typically highest in the winter when homes are heated and the air is stagnant.

Because most people don’t open their windows in the winter, radon has nowhere to go, causing it to build up in the house. As a result, the optimum time to test for radon is during the winter.

Radon gas rises through the earth and into the atmosphere, where it often finds its way into your house.

Because the ground surrounding your home freezes in the winter, radon gas is often redirected to a more convenient channel, which is directly into your home.

While it is not a substitute for appropriate radon mitigation, opening your windows can assist to dilute radon gas.

While you might open your windows in the spring and summer, it’s doubtful that you’d want to leave them open in the winter.

As a result, the radon gas in your home is sealed and gets more concentrated.

Warm air escapes from your home during cold weather through vents, drafty windows, and other openings at the top.

This airflow creates a vacuum, which draws air from lower levels, which is more likely to contain radon gas.

How Common is Radon in Homes?

It depends on where you live and what the radon levels are in your area. An important question to ask is, how common is radon in homes?

According to the Environmental Protection Agency (EPA), nearly one-third of homes in seven states had excessively high radon levels. Alaska is known to have the highest levels of radon, and Hawaii has the lowest levels of all 50 states.

Radon is an odorless, tasteless, and colorless radioactive gas that occurs naturally. Uranium is formed in rock, soil, and water through natural radioactive decay.

Radon is the second-leading cause of lung cancer in the United States, costing the country an enormous amount in healthcare expenses each year.

Radon has no obvious signs that warn people of its existence, and any issues only appear after years of exposure.

The safety of the family is a major consideration for most people, and avoiding an area with higher levels of radon is recommended if at all possible.

With an average radon level of 0 pCi/L, Hawaii has the lowest radon levels of all 50 states.

Hawaiian rocks have a low uranium content, and most rocks near the surface are permeable, allowing air entry to dilute radon.

The state with the highest radon levels, 10.7 pCi/L, is Alaska. Every two years, Alaskan homeowners are recommended to test for radon.

States with the Lowest Levels of Radon

Let’s take a peek at the states with the lowest levels of radon:

  • Hawaii (0)
  • Louisiana (1.1)
  • Mississippi (1.2) 
  • Florida(1.8)
  • Arizona (1.9)
  • Texas (2.1)
  • California (2.3)
  • Georgia (2.3)
  • Delaware (2.4)
  • South Carolina (2.4)

States with the Highest Levels of Radon

Now we will take a look at the states with the highest levels of radon:

  • Alaska (10.7)
  • South Dakota (9.6)
  • Pennsylvania (8.6)
  • Ohio (7.8)
  • Washington (7.5)
  • Kentucky (7.4)
  • Montana (7.4)
  • Idaho (7.3)
  • Colorado (6.8)
  • Iowa (6.1)

If you find that you find that you live in a state that is rated as having a lower level of radon, you will need to keep a few things in mind.

Even states with lower levels of radon still have what is known as “hot spots” with higher levels of radon in that particular area of the state.

How to Test for Radon in a Home?

Because radon gas cannot be seen or smelled, the only way to determine if you are being exposed to it is to take a radon test. So how do you test for radon in a home?

You can test for radon in a home by purchasing a radon test kit at your local hardware store or online. Instructions will be provided for the most accurate test results. Hiring a professional tester is also an option should you not feel comfortable testing for radon yourself.

You can take efforts to reduce radon levels in your house if they are too high.

The most typical way is to install a radon vent pipe system with a fan that takes radon from beneath the house and vents it to the outdoors.

Radon can also get into your home through your water supply, however, this is a far lesser danger than radon getting into your home through the soil.

If you have a private well, you may get it tested for radon. If the levels are high enough, the water supply can be treated to eliminate the radon before it gets into your house.

If you are concerned about radon levels in your water and it comes from a public source, you should contact your water provider.

The cost of lowering radon in your home might vary significantly, depending on how your property was built (whether you have a basement, crawlspace, or neither) and the type of system you want.

How Accurate is a Radon Detector?

It’s important to understand that radon detector accuracy can change based on the radon detector and what it’s being used for.

For example, radon detectors that test radon rates at low concentrations can be off by up to 30 percent.

Radon detectors that test radon rates at high concentrations can be off by up to 50 percent. However, radon detectors that are used for radon mitigation purposes show excellent results with accuracy rates of +/- 15%.

Most, if not all, commercially available radon measuring instruments are submitted to some type of proficiency testing when it comes to radon detector accuracy.

In collaboration with the US Environmental Protection Agency, the National Radon Safety Board evaluates radon measurement systems.

It stipulates that each device’s unique relative error be less than or equal to 20.0 percent and that all devices’ precision error be less than or equal to 20.0 percent.

The measurement conditions and calculations are described in detail here.

The National Radon Proficiency Program (NRPP) also provides performance testing with a 25% accuracy threshold.

Based on the requirements of these two programs, it’s reasonable to assume that short- and long-term radon detectors that pass one of these performance tests have an accuracy of around 25% or greater.

Where Should You Place a Radon Detector?

Regardless of what type of radon test is being used, there are some important things to keep in mind for the most accurate results. So where should you place a radon detector?

A radon detector should be placed 3 to 5 feet above the lowest floor in the home. Because the testing equipment will be elevated above the breathing zone, there will be no concern about the gas not being identified by the radon test.

When a licensed radon testing technician visits your house to install a radon testing device, he or she will follow careful guidelines to ensure the greatest testing accuracy.

If you bought a radon testing kit, this is crucial information to remember if you want your results to be reliable.

The following tips will help to ensure the most accurate radon test results possible.

  • Do not place the test in direct sunlight.
  • Place the test in an area where it won’t be handled or covered.
  • Realize that a neighbor’s radon levels may be drastically different that yours.
  • More than one testing unit is required for basements larger than 2,000 square feet.
  • Stay away from humidifiers like sinks, showers, and aquariums.
  • Air conditioning vents, fans, doors, and ventilation vents can all generate drafts, so keep the test away from them.


Trina Greenfield, Author
SmackDown Media LLC

About the Author:
Trina Greenfield, the owner of SmackDown Media LLC, is passionate about providing information to those interested in the air quality in and around their homes. Trina writes content about things she’s passionate about, such as safe, in-home air, educational platforms for children and adults, as well as all things family-related.