Is a radon level of 5 pCi/L bad?

See the 5 pCi/L page for this level in detail.

If your 5 came from one short-term test, take a followup test to be sure before you fix anything: a long-term test for a better understanding of your year-round average, or a second short-term test if you need results quickly. With two short-term tests, the higher the results, the more certain you can be that you should fix the home.

A 5 is a reason to act, not to panic. The time between exposure and the onset of lung cancer may be many years, and not everyone exposed to elevated radon will develop it. What matters is lowering the level where you spend your time and keeping it low.

Radon can cause lung cancer in both non-smokers and smokers, and a smoker exposed to radon has a much higher risk. Stop smoking and lower your radon level to reduce your lung cancer risk.

The method primarily used is a vent pipe and fan that pulls radon from beneath the house and vents it outside. Subslab suction, the most common and usually the most reliable method, typically lowers radon by 50 to 99 percent, and radon levels can be reduced in most homes to 2 pCi/L or below.

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1. 1Soil gas drawn from beneath the slab
2. 2Suction point through the slab
3. 3Vent pipe
4. 4Fan, outside the living space
5. 5Discharge above the roofline

Most homes can be fixed for about the same cost as other common home repairs. Get an estimate from one or more qualified radon mitigation contractors; many states require them to be licensed, certified or registered.

A confirmed 5 is a project with a clear order. Many states require radon professionals to be licensed, certified or registered, so check credentials when you collect estimates, and keep the follow-up test separate from the installer if you can.

Test within 30 days of installation to confirm the level came down, keep the fan running continuously, and retest at least every two years. You will reduce your risk of lung cancer when you reduce radon levels, even after living with an elevated level for a long time.

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1. Day of installation

   The system goes in

   Keep the fan running at all times: it must run continuously for the system to work correctly.

2. No sooner than 24 hours

   Earliest post-mitigation test

   Test no sooner than 24 hours after your system is in operation with the fan on, if it has one.

3. Within 30 days

   Post-mitigation test done

   A two- to seven-day measurement is recommended, and EPA recommends an independent follow-up radon measurement as well as any test the contractor runs.

4. At least every two years

   Retest

   Retest your home at least every two years to be sure radon levels remain low.

Test conditions: Windows and doors must be closed 12 hours before and during the test, except for normal entry and exit. Not drawn to scale.

After a remodel. After you remodel, retest in the lowest lived-in area to make sure the construction did not reduce the effectiveness of the radon reduction system.