How to Lower Radon Levels at Home

On this page (10 sections)

1. How do you know if your home needs radon mitigation?
2. What does a radon mitigation system do?
3. What is the radon mitigation process?
4. Can sealing foundation cracks lower radon?
5. How should mitigation differ by foundation type?
6. What should you ask a radon mitigation professional?
7. What does a follow-up radon test tell you?
8. How can you monitor the system and related household risks?
9. What should you do if radon remains high?
10. What is the practical plan for lowering radon?

To lower radon levels at home, use a qualified radon mitigation professional to choose and install a system, then test again to confirm the result. Sealing cracks may support mitigation, but it is rarely a dependable stand-alone solution for a high reading.

The right plan starts with a reliable measurement. Radon can enter through foundation openings and other below-ground areas, so the system must suit your home's foundation and how air moves beneath it.

How do you know if your home needs radon mitigation?

Consider mitigation when a reliable test shows 4 picocuries per liter (pCi/L) or higher. The EPA recommends fixing the home at or above that action level and says you may also consider a fix when results are between 2 and 4 pCi/L.

A short-term test is a useful screening step, but a single result can vary with weather, ventilation, and how the home is used. Follow the test instructions, and consider a second measurement or a long-term test when the result is close to the action level.

The [First Alert Radon Gas Test Kit] includes test materials and lab fees, except New Jersey state fees. The company says results are emailed within 72 hours of the lab receiving the sample.

Use test results to decide whether to contact a qualified mitigator, not to diagnose a health condition. If you need a refresher on test placement and timing, read How to Check Radon Levels: What That Means.

What does a radon mitigation system do?

A mitigation system reduces radon entry by changing air pressure beneath the home and routing soil gas outdoors. The common active method uses a pipe and fan to draw radon from below the foundation before it can enter living space.

A professional examines the foundation, radon readings, and likely soil-gas entry points before selecting a system. Homes with basements, crawl spaces, and slab foundations may need different layouts.

For a closer look at the process, see how a radon mitigation system works. The system's design, installation, and follow-up measurement all matter.

What is the radon mitigation process?

The process usually includes a home assessment, system installation, and a follow-up test. Ask the professional to explain what they found, what the proposed system will do, and how they'll confirm its performance.

1. Review the test results. Share the test type, dates, and readings with the professional.
2. Assess the building. The professional checks the foundation, accessible entry points, and system options.
3. Choose a design. The pipe route, suction point, and fan location depend on the home.
4. Install the system. The installer follows the selected plan and local requirements.
5. Measure again. A post-installation test checks whether radon levels are lower.
6. Maintain and retest. Follow the installer’s guidance for system checks and future measurements.

Ask whether the proposal includes a post-installation test, who will perform it, and what happens if the result remains high. Keep the test results and system instructions with your home records.

Can sealing foundation cracks lower radon?

Sealing cracks can reduce some openings, but it usually cannot control radon by itself. Radon may enter through multiple routes, including joints, drains, and spaces around pipes.

A mitigator may recommend sealing as one part of a larger system. Ask which openings will be sealed and how the work fits the ventilation or soil-depressurization plan.

Don't cover a sump pit or block a drain without professional advice. Those openings may need a sealed cover designed to work with the mitigation system.

How should mitigation differ by foundation type?

The foundation affects where a mitigation system draws soil gas and how its pipes are routed. Have a qualified professional match the design to the home's construction.

How do you reduce radon in a basement?

A basement system often draws soil gas from beneath the slab, with the pipe routed to an outdoor exhaust point. The exact setup depends on the foundation and where measurements show radon is entering.

Our guide explains how to reduce radon in a basement, including why a system should be planned around the house rather than a single visible crack. If the basement has a sump, ask how the system will handle it.

What if your home is built on a slab?

A slab home may need a suction point through the concrete and a vent route to the outside. The professional should consider the slab layout, accessible areas, and where the fan can be placed.

For details on this foundation type, see how to choose a radon mitigation system for a house on a slab. A system should fit the house layout and be checked after installation.

How is a system design chosen?

A system design sets the suction point, pipe route, fan location, and exhaust location. The right arrangement depends on the foundation and the way soil gas moves beneath the home.

Read how to choose a radon system design before comparing proposals. Ask each professional to explain why their design fits your home's test results and structure.

What should you ask a radon mitigation professional?

Ask about qualifications, the proposed design, the follow-up test, and ongoing system checks. A clear plan helps you understand how the contractor will address the reading and verify the change.

Questions to ask include:

• What parts of the home and foundation did you assess?
• Why does this system fit my foundation and test results?
• Where will the pipe and fan go?
• How will you confirm the system is working?
• Who performs the post-mitigation test, and when?
• What maintenance and future testing do you recommend?

Get the proposed work and follow-up plan in writing. Check local or state guidance for any contractor certification or licensing requirements.

What does a follow-up radon test tell you?

A follow-up test checks whether radon levels fell after the system was installed. Don't assume that a running fan proves the home is below the action level.

Follow the professional's instructions for when to test and where to place the device. Keep doors and windows in their usual condition during the measurement unless the test instructions say otherwise.

A short-term test can check a change sooner, while a longer measurement reflects more time in the home. For help understanding the measurement process, see How to Check Radon Levels: What That Means.

How can you monitor the system and related household risks?

Check the mitigation system as instructed, and keep radon measurement separate from other home alarms. A radon test measures radon; a water alarm and a carbon monoxide alarm address different hazards.

The Basement Watchdog water alarm has a detachable sensor with a 6 ft wire that can reach a sump pit or mount on a wall. It can alert you to water near a sump, which may help you notice a drainage issue that could affect the area around a mitigation system.

The First Alert plug-in carbon monoxide alarm has a digital display, battery backup, and an audible alarm. Carbon monoxide is different from radon, so use a CO alarm for its intended purpose and a radon test to measure radon.

Neither alarm measures radon or confirms mitigation results. Keep following the mitigator's system checks and use a radon test when you need to verify levels.

What should you do if radon remains high?

Contact the mitigation professional if a follow-up result remains at or above the action level. Share the test details and ask them to review the system, installation, and measurement conditions.

A system may need adjustment, repair, or a different design. Keep using the home as usual unless a qualified professional or local authority advises a temporary change.

What is the practical plan for lowering radon?

Start with a reliable test, then ask a qualified professional to assess the home if results reach 4 pCi/L or higher. Choose a system that fits the foundation, and include follow-up measurement in the plan.

For low readings, keep the test record and follow current testing guidance. For raised readings, use the professional's system plan and retest to confirm the result.

Frequently asked questions

When should you mitigate radon?

Consider mitigation when a reliable radon test shows a level at or above the EPA action level of 4 pCi/L. The EPA also advises considering a fix between 2 and 4 pCi/L.

Discuss the result and next steps with a qualified radon professional, and follow local requirements.

How do you mitigate radon in a house?

A qualified professional measures the home, chooses a system suited to its foundation, installs a vent path and fan when needed, and checks the result with a follow-up test. Active soil depressurization is a common method, but the right approach depends on the building.

Does sealing cracks lower radon?

Sealing foundation cracks and other openings can support a radon system, but it usually isn't enough on its own to lower a high reading reliably. Ask a qualified mitigator whether sealing is suitable for your home and how they will verify the result.

How long after radon mitigation should you retest?

Retest after the mitigation system is operating and the professional says the home is ready for a post-mitigation measurement. Use a test method and placement that follow current EPA guidance, and keep checking the system as directed because radon levels can change.