Radon Levels: The Good, the Bad, the Dangerous
Introduction
Radon is a colorless, odorless, tasteless and invisible radioactive gas formed in the earth’s crust. It is a part of the air we breathe. Radon is generated by the radioactive decay of radium. Radon levels can only be determined by testing.
Breathing radon over time increases your risk of lung cancer. Radon is the second leading cause of lung cancer in the United States. Nationally, the EPA estimates that about 21,000 people die each year from radon-related lung cancer. Only smoking causes more lung cancer deaths.
This article will discuss how radon levels are measured, what is considered a safe level, and what radon level will put you at a health risk.
How are radon levels measured?
Radon levels are measured by picocuries per liter of air, or pCi/L, which is one of the preferred measurements for the speed of decay in radon. The pCi unit is used in the United States because it is required by federal law. Just about everywhere else that uses the metric system, including the World Health Organization, measures in Becquerels. 1 pCi/L is equal to 37 Bq/m3.
Is radon dangerous outdoors?
Outdoors, radon disperses rapidly so levels are usually low and pose no significant health risk. The average global outdoor radon level varies between 0.135 and 0.405 pCi/L.

Why does radon build up in homes and buildings?
Most radon exposure occurs inside homes, schools and workplaces. Most people are familiar with the dangers of radon exposure, but many don’t know why it builds up in homes and buildings.
Radon is a gas that rises from the ground and can enter a home or workplace through cracks in the foundation and entry points for pipes. Modern homes and buildings are often well insulated to save on energy bills. However, little airflow can allow radon to build up to high levels and cause long-term exposure.
In the United States: on average, 1 of every 15 homes have radon levels that are higher than the recommended action levels.
What are safe radon indoor levels?
Indoors, radon levels up to 2.7 pCi/L are considered safe and no action is needed.
What are borderline radon levels?
Levels of between 2.7 – 4 pCi/L are still considered safe. However, since radon gas levels fluctuate, continuous monitoring is suggested. If this range persists for more than 3 months, contact a professional radon mitigator.

What are dangerous radon levels?
In the United States, the Environmental Protection Agency action level is a reading of 4 pCi/L and above. Radon levels of more than 4 pCii/L are dangerous to your health. Keep measuring. If this level is maintained for more than one month, contact a professional radon mitigator.
What influences radon levels?
There are many factors that can cause changes in radon gas levels:
- Temperature
- Air pressure
- Humidity
- Ventilation
- Building insulation
- Snowfall
- Ice
- Rain
- Earthquakes
Some of these factors (ventilation and building insulation) can be controlled by you. Most other factors are out of your control.
That’s why it’s important to test your home for radon regularly. Testing is the only way to know if you have a radon problem.

How does radon exposure affect our bodies?
Radon progeny can attach to dust and other particles and can be inhaled into the lungs. As radon and radon progeny in the air break down, they give off radiation that can damage the DNA inside the body’s cells.
All our cells contain DNA, which acts as an instruction manual or blueprint for cells on how to create copies of themselves. When an alpha particle hits our DNA it can cause damage to a cell’s blueprint. Cells constantly replicate themselves, but with a broken blueprint the replication process can become cancerous.
Lung cancer is the risk of long-term radon exposure
Long-term exposure to high levels of radon can lead to cancer of the lungs. The EPA estimates that radon causes about 21,000 lung cancer deaths every year in the United States. Radon is the number 1 cause of lung cancer amongst non-smokers. Only smoking causes more deaths.
What are the symptoms of radon exposure?
You can’t see, smell or taste radon gas. Even if you are breathing in a high level of radon, there are no obvious signs.
Exposure to high levels of radon over time puts you at risk of developing lung cancer. Unfortunately, radon poisoning symptoms often don’t appear until you either have cancer or are very close.
This may be the best reason to install a radon detector to continually monitor the radon levels in your home or business so you can take action before health issues arise.
Signs and symptoms of cancer in the lungs from radon exposure can include:
- Persistent cough
- Hoarseness
- Wheezing
- Shortness of breath
- Coughing up blood
- Chest pain
- Frequent infections like bronchitis and pneumonia
- Loss of appetite
- Weight loss
- Fatigue
If you experience any of these symptoms, you should see a doctor as soon as possible.
Are some people more sensitive to radon than others?
Yes. Radon is much more likely to cause lung cancer in people who smoke. In fact, smokers are estimated to be 25 times more at risk from radon than non-smokers.
Some researchers believe that genetics may play a role, as certain genetic mutations have been linked to an increased risk of radon-related cancer. Others believe that individual differences in lung function may account for some of the variations in susceptibility. 1 in 30 people is radon-sensitive.
All children are sensitive. Radon is 10x more dangerous for children according to Dr. Aaron Goodarz, the Canada Research Chair for Radiation Exposure Disease.

Why are children more susceptible to radon exposure?
- Children and adolescents grow quickly, and their cells are more sensitive to radiation. Since the effects of radiation take years to develop, individuals exposed to elevated levels of radon in their youth are more likely to develop radon-related illnesses later in life.
- Children have faster breathing rates (meaning that they take in more air–and more radon–per minute) which almost doubles the risk of developing lung cancer compared to adults. If tobacco smoke is also present in kids’ homes, the risk of developing lung cancer increases at least 20 times.
- Children tend to spend more time indoors than adults, increasing their exposure to radon.
- Another cause for concern is research suggesting that children who live in homes with high radon levels may have an increased risk of developing childhood acute lymphoblastic leukemia (ALL).
Radon levels in schools
Most people are familiar with radon gas only in the context of its dangers to human health in homes. However, recent research has shown that radon levels in schools may be higher than previously thought, posing a risk to the students and staff who spend their days inside these buildings.
An EPA nationwide survey of radon levels in schools estimates that nearly one in five has at least one schoolroom with elevated radon levels. The agency estimates that more than 70,000 schoolrooms in use today have high short-term radon levels. This is why the EPA recommends testing all schools for radon. By taking these precautions, we can help ensure that our children are safe from this invisible threat.
How can you reduce radon levels in your home?
Here are a few simple steps that you can take to reduce the level of radon in your home.
Ventilation
Experiment with ventilation by opening windows and vents to ensure air is flowing throughout the house.
Sealing access points
Draft excluders and rubber seals are inexpensive ways to seal around doors and other access points in a building. This can be beneficial if the aim is to reduce radon levels in basements. Ask your local DIY store for sealant recommendations.
Caulking
Using caulking products will enable you to seal entry points in the floors and walls of the home.
Clear natural underfloor ventilation
Homes with a suspended ground floor and space underneath often have underfloor vents. Oftentimes these can become blocked with foliage or dirt, so clear the obstruction to improve the ventilation. Note that some are intentionally blocked to prevent drafts, so speak to a professional if you are unsure.
Sealing cracks
Radon often enters buildings through the ground. Sealing large cracks and openings in any home is good for energy consumption and can also help with radon. As a gas, it can still get through smaller cracks, but as with anything, large entry points are unhelpful. There are numerous professionals that can help with this process too.
Test
Have your home tested for radon on a regular basis. The best way is to purchase one or more radon detectors and place them in radon-prone areas of your home.

What are the two kinds of tests for radon levels?
There are two main types of radon tests: passive tests and active tests.
A short-term radon test kit uses activated charcoal to absorb the radon gas in the air. Various short terms test kits will include some type of container filled with activated charcoal. You leave the canister in place for the required amount of time (usually 2-7 days) then send it off to a lab for analysis and the results.
Advantages
- Quick and easy. You can buy charcoal radon test kits at your local hardware store or online. Total testing time is usually between 2-90 days depending on the type of test.
- Low cost. Kits range from $10 to $25.
- Practical for screening purposes over a short period of time.
Disadvantages
- Some charcoal absorbers are more sensitive than others to temperature and humidity. They are also prone to absorbing other materials in the air that will throw the test results off.
- Many are inaccurate.
- Less likely to tell you a year-round average radon level.
- Each kit comes with its own kit and lab costs.
Active tests, on the other hand, pump air through a device called a continuous radon monitor. These small devices can be mounted on a wall or placed on a shelf.
Advantages
- Provide more immediate results.
- Monitoring is continuous and highly accurate.
- One-time expenditure.
Disadvantages
- More expensive than charcoal test kits.
- Run on batteries. Batteries last 1-2 years.
- May require more than one monitor, especially if you have a basement or multi-story home.
When should you contact a professional radon mitigator?
Although it is invisible, odorless and because it’s a radioactive gas, radon can be dangerous if it builds up to high levels. That’s why it’s important to have your home tested for radon on a regular basis.
If you find that your home has a radon level, which is maintained for more than one month, of greater than 4 pCii/L, you should contact a professional radon mitigator. A qualified radon mitigator will be able to install a radon mitigation system that will help to reduce the level of radon in your home.
Why is continuous radon testing necessary?
Radon is invisible and odorless, but it can be harmful to your health if you are exposed to high levels. Rado is a lung cancer risk. For every 2.7 pCI/L increase in long-term exposure, lung cancer risk rises by 16%. That’s why continuous radon testing is necessary.
Radon levels can be affected by many factors, including temperature, air pressure, humidity, ventilation, building insulation, your home’s foundation, snowfall, ice, rain, earthquakes, cold weather, wind, pressure and shifting soil. Even earthquakes and local construction can affect radon levels in your home. That’s why it’s important to have your home tested for radon on a regular basis.

What are radon gas monitors?
A radon detector is a small device that measures the amount of radon in the air. It can be mounted on a wall or placed on a table. Many models also display readings on your smartphone or tablet. I have an entire article devoted to radon detectors.
When it comes to your safety and health, radon detectors are just as important as smoke detectors or combustible gas monitors. While there is no foolproof way to prevent radon gas from entering your home, installing a radon detector can help you keep track of levels and take action if they become too high.
Summary
Radon gas is a colorless, odorless, and invisible gas that is produced by the natural breakdown of uranium in the earth’s crust. It can be harmful to your health if you are exposed to high levels, so it’s important to have your home tested for radon on a regular basis. It’s the second leading cause of lung cancer next to smoking.
Radon levels can be affected by many factors, including temperature, air pressure, humidity, ventilation, building insulation, your home’s foundation, snowfall, ice, rain, earthquakes, cold weather, wind, pressure and shifting soil.
Many people use charcoal radon test kits to test for radon levels in their homes. However, these kits can be inaccurate and may not provide year-round average radon levels. Continuous radon monitors are more expensive than test kits, but they are more accurate and provide continuous monitoring.
If you find that your home has a radon level of greater than 4 pCii/L, you should contact a professional radon mitigator. A qualified radon mitigator will be able to install a ventilation system that will help to reduce the level of radon in your home.
Radon detectors are small devices that measure the amount of radon in the air and can be helpful in keeping track of levels and taking action if they become too high. When it comes to your safety and health, radon detectors are just as important as smoke detectors.