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How do I reduce radon in my home?

By Radon411 Editorial TeamUpdated How we research

Short answer

To reduce or get rid of radon, the main method is soil suction: a vent pipe and fan that pull radon from beneath the house and vent it outside before it can enter. Confirm a high result first, hire a qualified contractor, and test again after the system is installed.

Next step: a certified professional designs and installs the fix. Find a mitigation professional

How to mitigate radon in a home: the method primarily used is a vent pipe system and fan that pulls radon from beneath the house and vents it outside, and it does not require major changes to the home. Active subslab suction is the most common and usually the most reliable radon reduction method. In a crawlspace home, a plastic sheet over the earth floor with a pipe and fan drawing from beneath it does the same job.

Sealing cracks makes such a system more effective but does not work on its own, and opening windows helps only while they stay open. Most homes can be fixed for about the same cost as other common home repairs.

What to do next: confirm the level with a follow-up test, get estimates from certified professionals through your state radon office, and test again once the system is running.

How do you get rid of radon?

Getting rid of radon means stopping it from coming in more than cleaning it out of the air. The methods that work best prevent entry: soil suction draws radon from below the home and vents it through a pipe to the air above the roof, where it quickly dilutes. Here is the path from a high result to a lower level, in order.

  1. Confirm the level

    Follow a high short-term result with a second test before paying for a system (see the next section).

  2. Call your state radon office

    Many states require radon professionals to be licensed, certified or registered, and the state office can point you to them. Get more than one estimate and check references.

  3. Let the contractor diagnose the house

    A contractor inspects the home and designs a system around it, and may use chemical smoke or a soil communication test to see how air moves under the floor.

  4. Install the system

    In most homes this is soil suction: a pipe through the floor or in from outside, a fan, and an exhaust above the roof. It does not require major changes to the home.

  5. Test again

    Test within 30 days of installation, but no sooner than 24 hours after the system is running with the fan on, with a two- to seven-day measurement, ideally by an independent tester.

  6. Keep it running

    Check the warning device, never turn the fan off, and retest at least every two years. See how often to test.

Step one: confirm the level before you fix

One is a first look, not a verdict. If it comes back high, follow up with either a or a second short-term test. The decision then rests on one long-term result or the average of two short-term results.

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.
The testing steps from a first short-term result to a decision to fix.

EPA recommends fixing a home when the radon level is 4 or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Buyers and sellers have three testing options of their own; see how to test for radon.

Which method fits your foundation

The house decides the method. Homes with a basement or a slab-on-grade foundation are usually treated with one of four kinds of soil suction: subslab, drain-tile, sump-hole or block-wall suction. Active subslab suction is the most common and usually the most reliable, and often a single suction point is enough. In a crawlspace, a high-density plastic sheet over the earth floor, with a pipe and fan drawing from under it, is the most effective approach when it is done properly.

Basement, slab-on-grade and crawlspace foundations, each with a section drawing and the radon reduction methods EPA lists for it, such as active subslab suction and submembrane suction.
Read this figure as text

  • Basement

    • Active subslab suctionThe most common and usually the most reliable radon reduction methodOne or more suction pipes are inserted through the floor slab into the crushed rock or soil underneath.
    • Drain-tile suctionSuction on drain tiles or perforated pipe is often effective in reducing radon levels.
    • Sump-hole suctionThe sump can be capped so that it can continue to drain water and serve as the location for a radon suction pipe.
    • Block-wall suctionUsed in basement homes with hollow block foundation walls, often in combination with subslab suction.
    • Passive subslab suctionRelies on natural pressure differentials and air currents instead of a fan; generally not as effective in reducing high radon levels as active subslab suction.

  • Slab-on-grade

    Concrete poured at ground level.

    • Active subslab suctionThe most common and usually the most reliable radon reduction methodSuction pipes may also be inserted below the concrete slab from outside the home.
    • Drain-tile suctionSuction on drain tiles or perforated pipe is often effective in reducing radon levels.
    • Passive subslab suctionUsually associated with radon-resistant features installed in newly constructed homes.

  • Crawlspace

    A shallow unfinished space under the first floor.

    • Submembrane suctionWhen properly applied, the most effective way to reduce radon levels in crawlspace homesA high-density plastic sheet covers the earth floor, and a vent pipe and fan draw the radon from under the sheet and vent it to the outdoors.
    • Active crawlspace depressurizationA less-favorable option that draws air directly from the crawlspace using a fan; it generally does not work as well as submembrane suction.
    • Crawlspace ventilationIn some cases, radon levels can be lowered by ventilating the crawlspace passively, or actively, with the use of a fan.

Any type of home

  • Sealing cracks and openingsA basic part of most approaches, but EPA does not recommend the use of sealing alone to reduce radon.
  • House or room pressurizationShould only be considered after the other, more-common techniques have not sufficiently reduced radon.
  • Heat recovery ventilator (HRV)More effective in reducing radon levels when used to ventilate only the basement.
  • Natural ventilationShould normally be regarded as only a temporary radon reduction approach.

Some homes have more than one foundation design feature. In these situations, a combination of radon reduction techniques may be needed to reduce radon levels to below 4 pCi/L.

Basement, slab-on-grade and crawlspace homes, and the reduction methods that suit each.

Many homes mix foundations, such as a basement under part of the house and a slab or crawlspace under the rest, and then a combination of techniques may be needed. The basement case in detail is in how to reduce radon gas in a basement.

How much each method lowers radon

Each technique has a typical range of reduction. The suction methods share the widest and highest range; passive and ventilation methods do less, and some last only as long as the windows stay open.

Typical radon reduction, EPA

Basement and slab-on-grade homes

  • Subslab suction (subslab depressurization)50 to 99 percentWorks best if air can move easily in material under slab.
  • Passive subslab suction30 to 70 percentMay be more effective in cold climates; not as effective as active subslab suction.
  • Drain tile suction50 to 99 percentCan work with either partial or complete drain tile loops.
  • Block-wall suction50 to 99 percentOnly in homes with hollow block-walls; requires sealing of major openings.
  • Sump-hole suction50 to 99 percentWorks best if air moves easily to sump from under the slab.

Crawlspace homes

  • Submembrane depressurization in a crawlspace50 to 99 percentLess heat loss than natural ventilation in cold winter climates.
  • Natural ventilation in a crawlspace0 to 50 percentCosts variable.

Any type of home

  • House (basement) pressurization50 to 99 percentWorks best with tight basement isolated from outdoors and upper floors.
  • Sealing of radon entry routesSee commentsNormally only used with other techniques; proper materials and installation required.
  • Natural ventilationVariable/TemporarySignificant heated or cooled air loss; operating costs depend on utility rates and amount of ventilation.
  • Heat recovery ventilation (HRV)VariableLimited use; effectiveness limited by radon concentration or the amount of ventilation air available for dilution by the HRV.
Typical radon reduction by technique. Techniques described only in words get no bar.

Some systems cut radon by up to 99 percent, and even very high levels can be brought down to acceptable levels. With today's technology most homes can reach 2 pCi/L or below. Zero is not the goal: see can radon be removed completely.

What helps a little, and what does not work alone

Measures people try first, and how far each goes
MeasureWhat it doesIts limits
Sealing cracksLimits the flow of radon and makes a suction system work betterNot a fix on its own: by itself it has not been shown to lower radon significantly or consistently, and normal settling opens new cracks
Opening windowsMixes outdoor air with indoor airOnce windows and vents are closed, levels most often return within about 12 hours; it is not mitigation
Heat recovery ventilatorBrings in outdoor air while recovering heatWorks best ventilating only the basement; its effect is variable
House pressurizationA fan pushes air into the lowest level to hold radon outOnly worth trying after the common techniques have not lowered radon enough
Air cleanersFilter or treat indoor airNot recommended for radon; keeping it out at the source is the approach that works

These measures still have a place. Opening windows and sealing cracks are reasonable ways to keep levels low in a home that is not above the , and sealing also cuts the loss of heated and cooled air. Whatever you change, test again afterward. More on windows is in does opening windows reduce radon.

What it costs to run and fix

There is no single price. The cost depends on how the home was built and how large the radon problem is; most homes can be fixed for about the same cost as other common home repairs, but costs vary widely, so get one or more estimates. A fix is much cheaper if a passive system was put in when the house was built.

Costs after the system is in
CostWhat to expect
ElectricitySystems with fans work better, but they slightly increase the electric bill
Heating and coolingMost systems lose some heated or cooled air, which can raise utility bills
Fan replacementFans may last five years or more and then need repair or replacement; the cost depends on labor and materials, so ask qualified mitigators for an estimate

Published installation prices, with their dates, are on the radon mitigation cost page.

Questions about getting rid of radon

Can you get rid of radon completely?

Not to zero. Outdoor air itself holds about 0.4 pCi/L, and bringing indoor air down to outdoor levels is not yet achievable in every home. Most homes can be brought to 2 pCi/L or below.

Can I reduce radon myself?

Hiring a qualified contractor is the safer route, because a poorly built system can raise the level. If you want to do it yourself, start with your state radon office for guidance and training courses. See do-it-yourself radon mitigation.

Do air purifiers get rid of radon?

Air cleaning is not recommended for reducing radon's health risk. The approach that works is source control, and the most effective technique is active soil depressurization. See do air purifiers get rid of radon.

Does sealing cracks get rid of radon?

Not by itself. Sealing is part of most systems and makes them work better, but on its own it has not been shown to lower radon significantly or consistently.

How soon after a system is installed can I tell it worked?

Test within 30 days of installation, but no sooner than 24 hours after the system is running with the fan on. See how long after mitigation you can retest.

What if the radon is in my well water?

That is a separate fix. Point-of-entry treatment removes radon before the water enters the house, while point-of-use devices treat only a small part of it. Aeration typically removes 95 to 99 percent and granular activated carbon 85 to 95 percent. See how to get radon out of water.

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