Quick Answer
If your short-term radon test shows 4 pCi/L or higher, the EPA recommends:
- 1.Run a second test to confirm results (radon fluctuates)
- 2.Get 2-3 quotes from certified radon mitigation contractors
- 3.Install a mitigation system (most reduce levels to under 2 pCi/L)
- 4.Retest 24-48 hours after installation to verify it's working
Average timeline: 2-4 weeks from test results to working mitigation system.
First: Understand What Your Results Mean
Radon is measured in picocuries per liter (pCi/L). The EPA action level is 4.0 pCi/L—the point at which mitigation is strongly recommended. But here's the critical context most people miss:
4-10 pCi/L: High Risk (Take Action Within 2-4 Weeks)
Living in a home at 4 pCi/L gives you roughly the same lung cancer risk as smoking half a pack of cigarettes per day. At 10 pCi/L, it's equivalent to a full pack per day.
What to do: Confirm with a second test, then schedule mitigation. Most contractors can install a system within 1-2 weeks of your call.
10-20 pCi/L: Very High Risk (Urgent Action Required)
At 20 pCi/L, your lung cancer risk is 35-40 times higher than the national average. This level requires immediate professional mitigation.
What to do: Contact certified contractors immediately. Consider reducing time spent in high-radon areas (usually basement) until system is installed.
20+ pCi/L: Extreme Risk (Emergency Mitigation)
Some homes test above 100 pCi/L. At these levels, you're being exposed to radiation equivalent to getting hundreds of chest X-rays per year. This is a health emergency.
What to do: Call 2-3 contractors today. Many offer emergency installations within 48-72 hours. Avoid sleeping in basement until system is operational.
Why 4 pCi/L is the Action Level
The EPA chose 4 pCi/L because it's the level at which mitigation becomes cost-effective relative to health risk reduction. But here's what they don't emphasize: there is no safe level of radon.
Even at 2 pCi/L, you're exposed to more radiation than the average outdoor level (0.4 pCi/L). The World Health Organization recommends action at 2.7 pCi/L. If your test shows 2-4 pCi/L, seriously consider mitigation—especially if you have children or plan to live in the home long-term.
Step 1: Confirm Your Results with a Second Test
Radon levels fluctuate daily and seasonally. A single short-term test is a snapshot—it might have caught an unusually high or low period. The EPA recommends confirming any result above 4 pCi/L with a follow-up test before spending $1,500+ on mitigation.
Two Confirmation Approaches:
Option 1: Second Short-Term Test (Fastest)
- • Run another 2-7 day test immediately
- • If both tests show 4+ pCi/L, proceed to mitigation
- • Total time: 5-14 days
- • Cost: $15-30
Best for: High readings (8+ pCi/L) where you want fast confirmation before calling contractors
Option 2: Long-Term Test (Most Accurate)
- • Leave test in place for 90-365 days
- • Accounts for seasonal fluctuations
- • Gives you annual average (what EPA uses for health calculations)
- • Total time: 3-12 months
- • Cost: $25-50
Best for: Borderline readings (4-6 pCi/L) where you want definitive annual average before deciding on mitigation
Recommended Confirmation Test Kits:
First Alert RD1 (2-Pack)
Short-term confirmation test
- ✓ Run second test immediately to confirm first results
- ✓ EPA-listed, lab fees included
- ✓ Results in 3-5 days after mailing
- ✓ Buy 2-pack to test both basement and main floor
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PRO-LAB Long-Term Test
90+ day alpha track detector
- ✓ Captures seasonal variations (winter/summer)
- ✓ Provides annual average radon level
- ✓ Best for borderline results (4-6 pCi/L)
- ✓ Lab analysis included
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Pro tip: If your first test showed 8+ pCi/L, don't wait for a long-term test. Run a second short-term test to confirm, then proceed to mitigation. You can always do long-term monitoring after the system is installed.
What If Results Are Inconsistent?
If your first test showed 6 pCi/L but your second test shows 3 pCi/L, don't ignore it. This indicates your home experiences variable radon levels. The EPA recommends using the higher resultfor decision-making, or running a long-term test to get the annual average.
Why the higher result matters: If radon spiked to 6 pCi/L once, it can spike again. That high-radon period is when you're most at risk. Mitigation protects you during those spikes.
Step 2: Get Free Quotes from Certified Radon Contractors
Once you've confirmed high radon levels, it's time to call professionals. Radon mitigation is not a DIY job—improper installation can actually increase radon levels or waste thousands of dollars on ineffective fixes.
⚠️ Why DIY Mitigation Usually Fails
Radon enters homes through complex pathways—foundation cracks, sump pits, block wall cavities, drain tiles. A pro uses diagnostic tools (pressure field extension testing, sub-slab communication tests) to identify the right suction point locations. DIYers guess. If you guess wrong:
- • You might reduce radon in one area while increasing it in another
- • Your system might work initially but fail after soil conditions change
- • You could depressurize the wrong area and pull radon in faster
- • You'll have wasted $200-500 on materials with nothing to show for it
At 8 pCi/L, every month you delay proper mitigation = another month of radiation exposure equivalent to smoking 16 cigarettes per day. Get it done right the first time.
What to Look for in a Radon Contractor:
State Certification or License
Every state requires radon contractors to be certified. Ask for their license number and verify it on your state's radon website. Unlicensed contractors cannot legally perform mitigation work.
NRPP or NRSB Certification
The National Radon Proficiency Program (NRPP) and National Radon Safety Board (NRSB) are the two national certification bodies. Look for contractors certified by either organization—this ensures they follow EPA protocols.
Written Warranty (Minimum 5 Years)
A good contractor guarantees their work. Most offer 5-10 year warranties that cover system performance (i.e., "we guarantee levels will drop below 4 pCi/L"). If levels don't drop, they fix it for free.
Post-Mitigation Testing Included
The EPA requires post-mitigation testing to verify the system works. Many contractors include this in their quote (either a short-term test or continuous monitor). If not included, budget an extra $20-150.
Insurance and Bonding
Verify the contractor carries general liability insurance and is bonded. This protects you if they damage your home during installation (drilling through pipes, cracking foundation, etc.).
Get Free Radon Mitigation Quotes
We connect you with certified radon mitigation contractors in your area. Get 2-3 quotes, compare warranties and pricing, choose the best fit. No obligation, no pressure.
Request Free Quotes →Average response time: 24-48 hours • Most contractors offer free in-home estimates
Questions to Ask During Quotes:
- • "What's included in this quote?" (labor, materials, post-test, warranty)
- • "How long will installation take?" (usually 3-6 hours)
- • "What type of system do you recommend for my home?" (sub-slab, drain tile, etc.)
- • "What radon level can I expect after mitigation?" (target: under 2 pCi/L)
- • "Do you offer financing or payment plans?" (some do for $1,500+ jobs)
- • "What's the annual operating cost?" (fan electricity: $50-150/year)
Step 3: Understand How Mitigation Systems Work
Before you sign a contract, it helps to understand what the contractor is actually installing. The most common system—used in 90%+ of homes—is called sub-slab depressurization.
How Sub-Slab Depressurization Works:
Contractor drills through basement floor
They cut a 4-6 inch hole through your concrete slab into the soil beneath. This creates a suction point where radon-laden air can be pulled from under your foundation.
PVC pipe runs from basement to roofline
A 3-4 inch PVC pipe is installed from the suction point, running up through your home (usually inside a closet or along an exterior wall) to vent above your roofline. This exhausts radon safely into outdoor air where it disperses harmlessly.
Specialized fan creates continuous suction
A radon-specific fan (not a regular ventilation fan) is mounted in your attic or outside. It runs 24/7, creating negative pressure under your foundation. This pulls radon gas out before it can enter your home.
Warning device monitors system
A U-tube manometer (pressure gauge) is installed in your basement. It visually shows that the fan is working. If the fan fails, you'll see it immediately and can call for service.
How effective is this? Sub-slab depressurization systems reduce radon by 90-99%. Most homes drop from 8-10 pCi/L down to 0.5-2 pCi/L after installation. Systems work immediately—radon levels start dropping within hours of turning on the fan.
Typical Mitigation Costs:
Annual operating costs:
- • Electricity for fan: $50-150/year (fan runs 24/7)
- • Maintenance: Minimal—fan replacement every 10-15 years ($200-400)
- • Testing: Annual retest recommended ($15-30/year)
Why Costs Vary
Several factors affect pricing:
- Foundation type: Slab-on-grade is cheapest. Basements with block walls or multiple levels cost more. Crawl spaces require membrane sealing.
- Number of suction points: Most homes need 1-2. Large homes or homes with multiple foundation types may need 3-4 suction points.
- Geographic location: Labor rates vary. Radon-heavy states (Iowa, Colorado, Pennsylvania) have more contractors and competitive pricing. Low-radon states have fewer pros and higher prices.
- Aesthetic routing: If you want the pipe hidden inside walls instead of exposed, expect to pay $200-500 more for the extra labor.
Step 4: Verify the System Works (Post-Mitigation Testing)
Installing a mitigation system is only half the job. You must test after installation to verify it's actually reducing radon levels. The EPA requires post-mitigation testing—and so should you.
⚠️ Don't Skip Post-Mitigation Testing
I've heard horror stories of contractors installing systems that don't work—either because they drilled in the wrong location, the fan wasn't powerful enough, or the home had complex soil conditions. Without post-testing, you're paying $1,500 for a system that might still be leaving you at 5-6 pCi/L. Test to confirm.
When and How to Test:
⏱️ Wait 24-48 Hours After Installation
Give the system time to stabilize pressure under your foundation. Testing immediately after installation may not give accurate results.
🧪 Use a Short-Term Test (2-7 Days)
You don't need a long-term test for post-mitigation verification. A short-term test (48-96 hours) will show if the system is working effectively.
Place the test in the same location you tested before mitigation (usually lowest lived-in level). This allows apples-to-apples comparison.
🎯 Target Level: Under 2 pCi/L
Most mitigation systems drop radon to 0.5-2 pCi/L. If your post-test shows 2-4 pCi/L, the system is working but could be optimized. If it's still above 4 pCi/L, the contractor needs to troubleshoot.
Recommended Post-Mitigation Test:
First Alert RD1 Short-Term Test
Quick verification test
- ✓ 2-4 day test gives fast results
- ✓ EPA-approved for post-mitigation testing
- ✓ Lab fees included
- ✓ Same test most contractors use
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Contractor note: Many contractors include post-mitigation testing in their quote. Ask before buying your own test kit—you might get it for free.
What If Post-Test Still Shows High Radon?
If levels are still above 4 pCi/L after mitigation, call your contractor immediately. Reputable contractors warranty their work—they'll troubleshoot and fix it for free. Common issues:
- • Suction point is in wrong location (need to drill additional hole)
- • Fan isn't powerful enough (need larger CFM fan)
- • Air leaks in system (joints not sealed properly)
- • Foundation cracks allowing radon bypass (need sealing)
A good contractor will diagnose and fix this within 1-2 days. If they push back or ask for more money, reference your warranty and demand they honor it. This is why written warranties matter.
Step 5: Monitor Long-Term with Annual Testing
Radon mitigation isn't "install and forget." Fans can fail, pipes can crack, soil conditions can change. The EPA recommends retesting every 2 years minimum—and annually if you have a mitigation system.
Why Annual Testing Matters:
Fans wear out over time
Radon fans run 24/7/365. After 10-15 years, bearings wear out and fans fail. Your U-tube gauge will show this—but only if you're checking it. Test annually to catch failures early.
Soil conditions change
Heavy rains, droughts, or ground settling can alter how radon moves beneath your home. A system that worked perfectly for 5 years might suddenly become less effective.
Home renovations affect radon
Finishing a basement, adding a room, or major HVAC work can change air pressure dynamics in your home. Always retest after significant renovations.
Consider a Continuous Monitor for Peace of Mind
Instead of buying a new $15 test kit every year, many homeowners with mitigation systems invest in a digital continuous radon monitor. These devices provide real-time radon readings on your smartphone and alert you if levels spike.
Airthings Wave Plus Smart Radon Monitor
Continuous monitoring with smartphone alerts
- ✓ Real-time radon readings updated every hour
- ✓ Smartphone app shows trends over time
- ✓ Alerts if radon spikes above safe levels
- ✓ Also monitors CO2, VOCs, temperature, humidity
- ✓ Battery-powered, no wiring needed
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Cost comparison: Continuous monitor costs $180-250 upfront but lasts 10+ years. Annual test kits cost $15-30/year × 10 years = $150-300. The monitor pays for itself and gives you daily peace of mind that your system is working.
Testing Checklist After Mitigation:
- ✅Week 1: Post-mitigation test (verify system works)
- ✅Year 1: Retest to confirm levels stay low
- ✅Year 2+: Test every 1-2 years
- ✅After renovations: Always retest after major work
- ✅Monthly: Check your U-tube gauge to ensure fan is running
Common Questions After Getting High Test Results
Should I move out until mitigation is installed?
Not necessary for most levels (4-20 pCi/L). Radon damage is cumulative over decades—a few extra weeks won't significantly change your risk. That said, if your test showed 50+ pCi/L, consider avoiding the basement until the system is installed. At those levels, every day matters.
Can I just open windows instead of installing a system?
Opening windows temporarily lowers radon while they're open, but levels return as soon as you close them. You can't keep windows open year-round (heating/cooling costs, security, weather). This isn't a solution—it's procrastination. Get a permanent fix.
Does radon mitigation lower home value?
No—actually the opposite. A properly installed mitigation system is a selling point. It shows you've proactively addressed a known issue. Homes without mitigation in high-radon areas are more likely to face buyer concerns during inspections.
Will my system make noise?
The fan produces a low hum similar to a refrigerator running. Most are installed in attics or outside where you won't hear them. If installed in a garage, you'll hear a soft whirring sound. It's not loud—most people forget it's even running after a week.
Can I turn off the system when I'm not home?
No. The fan must run 24/7 to maintain negative pressure under your foundation. Turning it off allows radon to accumulate again. The electricity cost ($50-150/year) is minimal compared to the health risk of intermittent protection.
What if I'm renting and my landlord won't install a system?
Landlord-tenant radon laws vary by state. Some states require landlords to test and mitigate if levels are high. Others don't. Document your test results, send a certified letter requesting mitigation, and research your state's tenant rights. If they refuse, consider moving—your health is worth more than any rental.
Take Action Today
High radon is scary, but it's fixable. Follow these steps and you'll have safe radon levels within 2-4 weeks.
Confirm Your Results
Run a second test to verify your initial results before spending $1,500 on mitigation.
Compare Test Kits →Get Mitigation Quotes
Connect with certified contractors in your area. Get 2-3 quotes, compare, and choose the best fit.
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