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Updated: Jun 15, 2022

Some call it breathable cancer. Doctors know it as the main cause of lung cancer in non—smokers. You might be completely unaware of it. But many of us are exposed to it. So what is radon? How does this radioactive gas harm your health? Why you might have not heard about it? And what you need to do right now to significantly lower your risk of lung cancer in a simple and affordable way. Read below to find out everything you need to know about this toxic gas.

Radon in lungs causes lung cancer

What Is Radon & Why Is It So Dangerous?

Radon is radioactive, carcinogenic gas without smell, color, or taste. It is a result of spontaneous radioactive decay of uranium, which is naturally present in the earth. Once it forms, it is easily released from ground to the air. Main route of human exposure is inhalation through which this toxic gas can cause lung cancer. In fact, radon is the number one cause of lung cancer in non—smokers.

Certain areas of the US are very rich in uranium so they are typically high in radon. While radon is present in outdoor air, concentration is negligible. However, the concentration increases sharply when radon enters closed space where it accumulates (ex. house, office, school). Since radon is much heavier than air, it accumulates the most in the lowest levels of a building, such as basements and ground floors.

Besides inhalation, the other exposure route is through drinking water contaminated with radon. This is however, a much smaller concern and only an issue if your water comes from certain underground wells.

You can read more about the dangers of radon on the EPA website.

But I Have Never Heard Of It

If you have never heard about radon or know very little about this silent killer, I don't blame you. Even though information about it is readily available online, on EPA and CDC websites, radon is not given nearly enough attention as it should be, considering how deadly it is. To illustrate this point, below are some stats about number of people who die every year in the US from different causes:

As you can see, twice as many people die from radon caused lung cancer than from drunk driving. And 50 times less people die from carbon monoxide poisoning than from radon caused lung cancer. And yet, we see so many campaigns, education efforts, and activism around drunk driving and carbon monoxide prevention, all of which I fully support. But what's shocking is how little we hear about the dangers of radon, even though it kills almost twice as many people as drunk driving and carbon monoxide combined.

Radon kills almost twice as many people as drunk driving and carbon monoxide poisoning combined.

One way you will for sure hear about radon is if you are buying a house and you are very meticulous about reading contracts before signing (ahem, how many of us do this?). Some states include mandatory radon inspection as part of the real estate contract. If radon levels exceed action levels set by EPA, the seller is required to mitigate radon or give a refund to the buyer so they can fix the problem themselves. EPA has even published a Home Buyer's and Home Seller's Guide to Radon. But this is not mandatory everywhere and if it is, typically real estate agents take care of this without you even knowing.

"Radon in your home is equivalent to smoking 4—8 cigarettes a day." Kate Siefert, health commissioner from Ohio
Man sick with lung cancer
Photo by Pexels (Vlada Karpovich)

Children Are The Most Affected

When talking about health hazards of radon, unfortunately children are more susceptible to exposure than adults. This is because their lungs are smaller, their respiratory rates are higher, and their bodies are more sensitive to radioactivity. Hence, children absorb higher radiation doses than adults. In addition, radon levels are the highest in the lowest area of the house (floor vs. ceiling, basement vs. first or second floor, etc), so a very small child crawling on the floor may be breathing higher radon levels than adults standing in a room. According to CDC:

Risk of lung cancer in children due to radon exposure may be twice as high as the risk to adults.
If children are also exposed to tobacco smoke, the risk of lung cancer is at least 20 times greater.
Child playing on the floor
Photo by Pexels

Why You Need To Test Your House Now

Considering that radon is an invisible, odorless gas that can be present in any house in any neighborhood in the country, testing your house is the only way to tell what levels you and your family are exposed to on a daily basis.

EPA provides a map of radon levels for each US county. EPA divides the counties based on radon levels into three zones:

  • Zone 1: red zone — highest radon level of > 4 pCi/L

  • Zone 2: orange zone — medium radon levels between 2 and 4 pCi/L

  • Zone 3: yellow zone — lowest radon levels < 2 pCi/L

This map is a great starting point, as some states are entirely in the red zone (ex. Iowa, North Dakota, etc.), which means that each house should be tested for radon.

But this map is not enough. If you see that your county is in the yellow zone, your house could still have levels in orange or in some cases even red zone. This is because radon levels fluctuate locally, even between houses in the same county. Studies show that 1 out of 15 homes in the US has unsafe levels of radon. And the tricky part with radon (unlike with some other toxic gases like carbon monoxide) is that exposure doesn't cause symptoms. There are no warning or irritation signs. So unless you test your home, school, or office, you will not know if you are exposed to dangerous levels of radon until it is too late or someone is diagnosed with lung cancer.

These are all the reasons why everybody who owns a house needs to test their radon levels.

People living on higher floors of apartment buildings typically don't need to test their radon levels, as they are likely comparable to low, outdoor levels. This is because radon concentration is the highest closest to the ground.

Every house needs to be tested for radon. 1 in 15 homes in the US has dangerous levels of radon. If you use your basement your risk is even higher.

How To Test For Radon

Testing is very simple to do and quite inexpensive. You can hire a professional to do it or you can order a test kit and do it yourself. It really takes only a few minutes to set the test up. After testing you simply mail the test kit to a testing lab and you will receive your results.

Types of Radon Tests

  • Long—term test (3 to 12 months): This test gives the most reliable results because it takes into account change in radon levels over the year. This is important because radon levels can change significantly throughout the year, with levels being higher during cold months (October to March) and in some climates fluctuating between summer months too.

  • Short—term test (2—4 days): This test is just a snapshot of radon levels in one short period of time, but it is inexpensive and quick to do. It should be done at least twice in the same year, once during the colder months and once in the summer, to get an accurate picture of your year—round exposure.

  • Continuous monitoring: If you want a piece of mind at all times, you can purchase devices that continuously monitor radon levels, with daily, monthly, or yearly reports. Some examples are radon monitors by Air Things or check this article for the top rated continuous radon monitors. If you properly measured and mitigated radon in your home, these continuous monitors are a nice—to—have but definitely not necessary.

Where To Buy Testing Kit

EPA recommends to get your radon testing kits from The National Radon Program Services at Kansas State University. They sell reliable kits at discounted prices, $17 for short—term kit and $27 for long—term kit (order here). Test kits are also available in many online and home improvement stores, like Walmart, etc.

If you are doing testing by yourself, make sure to follow all instructions in the kit, such as placing the kit at the lowest level of the house that you use (typically a basement), keeping all windows and doors closed during the measurement, and setting the testing unit at a specified height from the floor. All these are crucial for accurate measurement.

When to Mitigate Radon

Once you test your home and get the results, the question is when you should do something about them. EPA provides guidelines on this:

  • Levels >=4 pCi/L Mitigate radon as these levels are unsafe.

  • Levels 2—4 pCi/LMitigate radon as there is no safe level of radon, and these levels can easily be reduced.

  • Levels <2 pCi/LNo action required according to EPA.

These EPA guidelines are based on calculation of how many lung cancer cases per year are caused by different levels of radon exposure (see table below).

If you are a smoker your risk of lung cancer from radon exposure is approximately 10 times higher vs. non—smokers

However, there is no safe level of radon. While the level can never be 0 pCi/L, with proper mitigation in the most cases levels can be reduced below 1 pCi/L. And since lung cancer is very lethal with some of the lowest survival rates, the stakes are very high here. Hence, we recommend considering radon mitigation for levels 1—2 pCi/L. If levels are >1pCi/L, consider yourself lucky as no further action is needed.

How to Mitigate Radon

Mitigation Methods

There are two main mitigation methods:

  • Preventing radon from entering the house: This is done via sub—slab depressurization, which vents air from beneath the foundation. This work should be done by a qualified contractor. Other methods include sealing cracks in the foundation or walls.

  • Venting radon out of the house: This involves installation of specialized fans or blowers to remove radon from the air in the lowest level of your house. This is what we did in our house. The whole installation, done by a certified contractor, took only a few hours.


Majority of homes can be permanently fixed for under $2,000, which is cost—effective for preventing long term lung cancer risks for the whole family.

Who To Call

Radon mitigation has to be done by a professional. Below is the list of EPA recommended resources to help you find certified and licensed professionals in your state:


  • Radon—caused lung cancer kills 21,000 people a year

  • Radon is the main cause of lung cancer in non—smokers

  • Children are twice as likely to get lung cancer from radon than adults

  • Radon significantly amplifies risk of lung cancer in smokers

  • If you use or live in your basement, your risk of exposure is even higher

  • 1 in 15 houses in the US has dangerously high radon levels

  • Every house should be tested for radon

  • Radon test is simple and inexpensive Order your radon testing kit today!

  • Radon levels can be reduced in any house with affordable and permanent radon mitigation measures

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