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Owning and renting4 min read

Is it safe to live in a house with radon?

By Radon411 Editorial TeamUpdated How we research

Short answer

Every house has some radon, so safety depends on the level: the lower it is, the lower the risk, and even levels below 4 pCi/L pose some risk. A high result is a reason to confirm it and fix the home, not to move out overnight, because the risk builds over years.

Next step: check the rules where you rent or let. Radon rules for rentals by state

All outdoor and indoor air has some radon in it. The average indoor level is estimated at about 1.3 , against about 0.4 pCi/L normally found outside, so there is no zero to aim for, only a lower number.

Your chance of lung cancer from radon depends mostly on the level in your home, the time you spend there, and whether you smoke or have ever smoked. A smoker exposed to radon has a much higher risk.

There is time to do this properly. It takes many years for lung cancer to develop, and you reduce your risk when you reduce radon levels, even after living with an elevated level for a long time. Some radon reduction systems cut levels by up to 99 percent.

What to do next: test the lowest lived-in level if you have not, read the result with the interpreter, and if it calls for a fix, get quotes from trained professionals and test again once the system is running.

Every house has some radon

All outdoor and indoor air has some radon in it, so the useful question is not whether a house has radon but how much. The average indoor level is estimated at about 1.3 , and about 0.4 pCi/L is normally found in outside air.

Scale of radon levels from 0 to 10 pCi/L marking EPA's 2 pCi/L level, where EPA says to consider fixing, and its 4 pCi/L action level, where EPA says to fix the home, with each mark also in Bq/m³.
Read this figure as text
  • Below 2 pCi/L (below 74 Bq/m³)Below both of EPA's guidance levels.
  • 2 to 4 pCi/L (74 Bq/m³ to 148 Bq/m³)EPA recommends considering a fix when the level is between 2 and 4 pCi/L.
  • At or above 4 pCi/L (148 Bq/m³ and up)EPA recommends fixing a home when the radon level is 4 pCi/L or higher.
Where a result sits against EPA's marks at 2 and 4 pCi/L.

Even levels below 4 pCi/L pose some risk, and the lower the level, the lower the risk. So a house with radon is not a yes-or-no safety question; it is a number to measure and, if it is high, to bring down.

What the risk depends on

Breathing in high levels of radon over time may cause lung cancer. Your chance depends mostly on three things, and two of them are about time. The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States.

What sets the risk of living with radon
FactorWhy it matters
The radon level in your homeThe higher the level, the higher the risk
How much time you spend at homeHigh levels where you spend the most time matter most
Whether you smoke or have ever smokedA smoker exposed to radon has a much higher risk of lung cancer

At the average indoor level of about 1.3 pCi/L, a person who never smoked has about a 2 in 1,000 chance of lung cancer and a smoker about 20 in 1,000. See how radon causes lung cancer.

There is time to act properly

An elevated result is a reason to plan a fix, not to move out overnight. It takes many years for lung cancer to develop, and the time between exposure and the onset of the disease may be many years. Not everyone exposed to elevated radon will develop lung cancer.

What to do with your result

Because radon levels vary from day to day and season to season, a single short-term result is a starting point. If it is high, take a followup test to be sure, then decide.

Flowchart of EPA's radon testing steps: take a short-term test; at or above 4 pCi/L follow up with a long-term or a second short-term test; then fix the home or consider fixing based on the result or the average of the two tests.
Read this figure as text

  1. 1Step 1: Take a short-term test.

    • Below 4 pCi/LEven if your test result is below 4 pCi/L, you may want to test again sometime in the future.
    • At or above 4 pCi/LIf your result is at or above 4 pCi/L, take a followup test to be sure.

  2. 2Step 2: Follow up with either a long-term test or a second short-term test.

    • Long-term testFor a better understanding of your year-round average radon level, take a long-term test.
    • Second short-term testIf you need results quickly, take a second short-term test. If your first short-term test result is more than twice EPA's 4 pCi/L action level, you should take a second short-term test immediately.

  3. 3Step 3: Decide whether to fix your home.

    • After a long-term testFix your home if your long-term test result is 4 pCi/L or more.
    • After a second short-term testConsider fixing your home if the average of your first and second test is at or above 4 pCi/L.
From a first short-term test to a follow-up, then to a decision to fix or consider fixing.

Read your number with the result interpreter, and see what a safe level of radon is.

Making the house safer

A high level can be brought down. The method primarily used is a vent pipe and fan that pulls radon from beneath the house and vents it outside; some systems cut radon by up to 99 percent, and most homes can be fixed for about the same cost as other common home repairs.

What lowers radon in a lived-in home, and what does not
ApproachEffect
Soil suction system (vent pipe and fan)Some systems reduce radon by up to 99 percent
Opening windowsOnly temporary; levels most often return within about 12 hours of closing up
Sealing cracks aloneNot shown to lower radon significantly or consistently
Stopping smokingLowers the combined lung cancer risk from radon and smoking

After a system goes in, test within 30 days to confirm it worked. See radon mitigation.

Questions about living with radon

Is it safe to live in a house with radon?

Every house has some radon. The question is the level: the lower it is, the lower the risk, and a high level can be fixed.

Should I move out if my radon test is high?

There is time to confirm the result and arrange a fix; lung cancer from radon takes many years to develop. Take a followup test, then fix the home if it is confirmed high.

Is radon below 4 pCi/L safe?

Even levels below 4 pCi/L pose some risk, and you can reduce your risk by lowering your radon level.

Is radon more dangerous for smokers?

Yes. A smoker who is also exposed to radon has a much higher risk of lung cancer. Stopping smoking and lowering radon both reduce the risk.

Does opening windows make a radon house safe?

Only for a while. Once windows, doors and vents are closed, radon most often returns to previous levels within about 12 hours.

Can a house with radon be made safe?

A radon reduction system can cut levels by up to 99 percent in some homes. Test again after it is installed to confirm the result.

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