Radon Testing: The Ultimate Guide


Radon gas is a radioactive gas that forms naturally from the decay of uranium. It is colorless, odorless, and tasteless, making it difficult to spot without testing. In fact, one out of every 15 homes in the United States has unsafe levels of radon gas. Radon can increase your risk for lung cancer if you are exposed to it daily over a long period of time.

Many people believe that testing for radon is a difficult and expensive process. But nothing is far from the truth. You can get a radon test done for less than $40. This is a guide to help educate people about radon testing, its necessity, the process, and costs. I try to cover as much as I can in this article; feel free to comment if you need any more information.

Radon testing

What is the need for radon testing?

Radon testing is a critical process that every homeowner should undergo to ensure the safety of their loved ones. If you are thinking of buying a home, this is the first thing you should do before signing the papers.

Long-term radon exposure can cause lung cancer. According to EPA, it is the number one cause of lung cancer among non-smokers, ie, non-smokers have more chances of getting lung cancer due to radon exposure than from inhaling secondhand smoke! It is also the second leading cause of lung cancer among those who smoke. (https://www.epa.gov/radon/health-risk-radon)

Unfortunately, Radon is a gas that cannot be smelled or tasted. Therefore, its presence can go undetected for a long time, increasing health risks to the residents of your home. Doing Radon testing is the only way to determine whether your home is free from risks or not, and that is why it is important to run a Radon test yearly and when you buy or sell a home.

How much Radon is safe

As per EPA, you should install a radon mitigation system if the Radon levels in your home exceed 4 pCi/L (picocuries per liter). They also recommend that people should consider reducing the levels if its goes above 2 pCi/L. (Source)

But unfortunately, there are no safe levels of Radon. EPA’s recommendation is just a guideline. WHO recommends reducing radon levels if it exceeds 2.3 pCi/L. Some mitigation systems can reduce radon levels by as much as 99%. The outdoor air is estimated to have 0.4 pCi/L of Radon on average, and this varies with the geography of the land.

The radon level recommendations are not limited to homes. Apartments, condominiums, hotels, offices, or any other building can have unsafe levels of radon gas. Hospitals and laboratories should also have Radon tests done since his radioactive gas can be present in these places as well.

Types of radon tests

There are two types of radon tests based on the time taken to complete these tests. They are;

  • Short term tests
  • Long term tests

How long does a radon test take? The duration of the test depends on the type of testing conducted. A short-term radon test takes anywhere from two to seven days to complete, whereas a long-term tests take more than ninety days and up to one year.

Short term radon tests

Short-term tests are the simplest, fastest, and cheapest test to run. All you need to do is buy a test kit, put it where you want to get the reading, and after 48 hours, send it to the lab to get the results.

But short-term test kits are not that accurate. This is because they read the radon levels of your home only for a few days. Radon levels are affected by seasons and many other factors. Radon levels are pretty high during the winter season since your house is closed up as opposed to summer, where there is more air circulation in the house. So if you do short-term testing during the summer season, the levels will be much lower than they are in winter. So short-term tests are only used to quickly assess the radon levels; it is the long-term kits that give you more accurate results.

Short-term radon tests are usually done with charcoal-based kits. They are inexpensive and are available in hardware stores as well as online marketplaces.

Long term radon tests

Long-term radon tests are expensive as compared to short-term tests. However, they are also accurate and give you more detailed information about the radon levels in your home. They take somewhere from a couple of months to a whole year, depending on what part of the home you want testing done and the type of radon test kit you prefer.

Long-term tests are usually done using alpha track test kits. They have a foil inside, on which the alpha particles released by the decay of radon atoms create tracks. The radon levels are assessed based on the number of such tracks formed. They are inexpensive, just like short-term test kits.

Once the testing is complete, these detectors are sent to the lab for analyzing the sample. The samples travel to the lab by courier service. You can get the test results within a day, depending on the service provider you opted to use.

Should I do a long-term test or a short-term test?

Start with a short-term test if testing for radon in your home for the first time. A short-term test help to quickly assess the radon levels in your home. This helps to install a mitigation system immediately without prolonging the risks if the levels are unsafe.

While doing the short-term test, do the long-term test as well. A Long-term test should be run for a minimum of 90-days, and it will give you the average annual radon level in your home. As radon levels can vary depending on the seasons and the frequency of use of HVAC systems, it is important to do a long-term radon test even if the short-term test levels show your home is safe.

Types of radon test kits

There are mainly two types of radon test kits; passive and active. Active test kits use electricity to power them, while passive kits do not require any power. Active test kits provide continuous readings of the radon levels, while passive test kits take days and even months to get results.

Active test kits can cost hundreds of dollars, whereas passive ones cost $20 to $50. Active kits are not required for your home unless you are too worried about radon levels. Running a long-term test once a year is more than enough to prevent radon exposure. However, active test kits are useful to alarm you of radon levels if your mitigation system stopped working.

Passive radon test kits

Passive radon test kits involve charcoal-based as well as alpha-track test kits. They are used either for short-term or long-term testing. These kits are exposed to radon for days or even months, depending on the testing, and sent to the lab to analyze the sample and get the results. These are inexpensive, old-school options.

Here are some good passive radon test kits

AccuStar radon test kit

AccuStar radon test kit

Check in Amazon

First Alert radon test kit

First Alert radon test kit

Check in Amazon

Active radon test kits

Active radon test kits are used to monitor radon levels in your house continuously. They can be placed anywhere in the living areas, just like a thermostat, and the kit will display the current radon level. These monitors are usually connected to a mobile app so you can get the day-to-day data and compare the levels with the previous year’s.

These kits can cost hundreds of dollars, but they are very accurate.

A radon monitor for basement

Certified professionals also use active radon test kits to assess the radon levels in homes before they are sold or bought.

Here is a good radon monitor to continuously record the radon levels in your home;

Corentium Home Radon detector

Corentium Home Radon detector

Check in Amazon

How to perform a radon test?

A radon test can be done by yourself or by a professional. If you merely want to know the radon levels in your home, buy a test kit online and perform the test yourself. If you are buying or selling a home, testing by a certified professional is needed.

If you are doing the test by yourself, I recommend buying a short-term kit to assess the current radon levels and a long-term testing kit to monitor the radon levels throughout the year.

Here is how to perform a short term radon test

  1. Buy a short term test kit

You can buy a short-term kit from stores or online marketplaces. You can also get it at a discount from National Radon Program Services (https://sosradon.org/test-kits).

  1. Keep the doors and windows closed

Close the windows and doors at least 12 hours before you begin testing. You have to keep the house closed during the test, and any doors opened should be closed immediately. Open doors and windows will tamper with the test results as the wind can move the radon gas away from the detector. Also, make sure you run heating or cooling as you would normally. The best time to do a short-term test is in winter as the house is kept closed during the season.

  1. Place the test kit in the lowest living area

Follow the instructions in the manual that comes with the test kit. You will have to write your contact details, and the time the test started on the form provided on the test kit. Place the test kit in the lowest level of the home, where you spend at least 10 hours a week. If you have a basement and spend your time there, place the test kit there. Do not put it on the floor. Instead, place it at the breathing level, 3 to 5 ft from the ground. Also, place it away from the walls, drafts, and heating to avoid false readings.

  1. Send the kit to the lab

A short-term test should be done for at least 48 hours and at most 7 days, depending on the instructions on the kit you purchased. Once the test is complete, return the kit to the lab as instructed in its manual. The lab will send you the results back, and based on the results; you can take whatever action necessary.

You can buy more than one short-term detector and place them in different rooms to test their radon levels.

How long does it take to get radon test results from the lab?

Once the lab gets your test kit, you will get the test results within one day via email. Depending on the lab you chose, you can also check the test results online or call them. In addition to this, you will also get a printed result within one or two weeks.

How do I know if the test kit I bought is valid?

When you buy a radon test kit, make sure that you choose a reputable company that has been in the business for many years. Look at their profile on social media and make sure that they have positive reviews from other customers. Also, read reviews from other individuals who have used the company’s products. Also, check for the expiry date on the kit. Many kits do not have expiry dates, but some do.

How to detect radon in water?

Radon gas can be present in water as well. This happens mostly in rural areas where water comes from an underground source, ie a well. If you have a surface water source, the radon in it will escape into the atmosphere. But since well water has no contact with air, it retains the radon gas and will enter your home through the pipes.

radon in water

There is no method to detect the presence of radon in water by yourself. What you can do is, take samples of the water and send them to a lab for testing. Radon levels in water are considered to be high if they exceed 10,000 pCi/L.

Here is a video detailing how to take a sample of water for radon testing;

The presence of radon in water can increase the overall radon levels in your home. The levels detected by the test kits show this increased level. To correctly assess how much radon your air has, subtract 1 pCi/L from the indoor reading per 10000pCi/L of radon found in water. So if the radon level in water is 20,000pCi/L, that means it adds 2 pCi/L to your indoor air radon levels.

If radon levels are high, you can mitigate them by using a charcoal-based water filter or aerating the water with fresh air.

What can affect radon test results

The accuracy of radon test results can vary based on several factors. They are;

  1. Extreme weather conditions:

Rains and storms can cause changes in indoor radon levels. Radon gas enters a home because of the pressure difference between the house and the ground. The house acts as a vacuum that sucks the radon gas out of the ground. The same effect but on a smaller scale happens outdoors as well.

When it rains, the ground becomes flooded with water which creates a positive pressure preventing radon gas from escaping into the air. So the gas will find an easier way out, through your home. So during rains and storms, the radon levels in your house will be higher than usual, and this can affect short-term radon test results.

  1. Open doors and windows

Opening a window can affect radon test results if the placement of the test kit is near it. Open doors and windows increase the air circulation inside the house, moving most radon gas to the outside. This reduces the radon levels recorded by the test kits.

  1. HVAC systems

Improper HVAC installation can cause the system to suck more air from some areas in the house. This will create negative pressure in such areas drawing more Radon into the house. Adding partitions and doors also can cause pressure changes in the house, affecting radon test results.

In addition, the drafts created by HVAC components like furnaces and fans and household appliances like vacuum cleaners and clothes dryers can prevent the test kit from taking accurate radon levels.

  1. Improper placement of the test kit

One should place the test kit in the lowest living space of the house. It should be placed at the height of 3 to 5 feet. One shouldn’t place it near any household appliances or HVAC systems, and the test kits shouldn’t be moved during the test duration. Failing to do any of these can alter the test results.

Can one manipulate a radon test?

It is pretty easy to manipulate a radon test results. All you have to do is open a few windows of the house, and the test kit will record lower levels of radon. People try to tamper with the test results when they are selling their homes. There are many incidents where homeowners did similar things to avoid installing a radon mitigation system at their cost.

For this very reason, it is very important to hire a certified professional to get the tests run. These professionals use a radon monitoring kit that continuously records radon levels. If the house owner tries to manipulate the test, the sudden drop in the radon levels will be recorded by the instrument. An experienced professional can easily spot this discrepancy and notify the buyer that the test is tampered with.

The buyer of the house should make sure that the testing is done via a radon monitoring kit and not a short-term test kit. It is impossible to know if the test is manipulated or not if passive testing kits like short-term kits are used.

How much does a radon test cost and who does it

The cost of radon tests vary from $30 to $70 if you are doing it yourself using a short-term or a long-term testing kit. This cost also includes the cost paid to the lab for analyzing the sample. Hiring a professional to do the test can cost you anywhere from $125 to $340 depending on your postcode.

How often should you conduct a radon test?

You should do a radon test before buying a home. If the radon levels are low, you can wait for two years until the next test. One should also do radon tests after renovating or making structural changes to the house as this can elevate radon levels. This also includes installation or modification of your HVAC equipment.

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