Radon Levels & Zone Map in Manassas, VA
Direct Answer for basement and lowest-level tests: Manassas is a strong county-level radon signal. You still need a home test, but this is not a county where skipping the first test makes sense.
Do not guess in a higher-risk county
Most users should either get a first test or move a 4.0+ result straight into mitigation pricing.
Official source shows a highest reported county value, not a county average.
2.0-3.9 pCi/L usually means retest or track. 4.0+ is where EPA action and quote planning start to matter.
No reading: test now. Reading at 4.0+: move into mitigation planning.
Measured Radon Data
Manassas evidence before the next step
Manassas, VA has more than the EPA map: Virginia Department of Health exposes 19 reported tests, and 37.7 pCi/L high-end signal for 2016-2024.
Source window
2016-2024
Processed verdict
Official high-end signal
Directional confidence - 50/100
Highest measured
37.7 pCi/L
59th percentile in-state
4.0+ signal
Not available
n/a in-state
High-end signal
37.7 pCi/L
59th percentile in-state
County-specific verdict
Manassas has an official high-end county result of 37.7 pCi/L, but no county average in this source.
Manassas is not being judged from an average table here. Virginia Department of Health exposes a highest measured county value of 37.7 pCi/L, so the useful decision is proof of local spike potential: test the home directly, then use a 4.0+ property result for mitigation pricing. It ranks at the 59th percentile for high-end readings among measured counties in the state.
Real-estate use
Buyer or seller use: do not negotiate from the highest county value alone. Use it to justify requiring a fresh lowest-level property test, then price quotes or credits only from the home's own 4.0+ result.
Manassas should be treated as a direct-test county: the official high-end value reaches 37.7 pCi/L, but the source cannot tell whether a specific home is high until that home is tested.
Choose Next StepHigh-end-source answer
What does the highest reported radon result mean in Manassas?
Virginia Department of Health reports a highest measured county value of 37.7 pCi/L for Manassas. That is a high-end local signal, not a county average. The practical answer is to test the property and let the home's result decide mitigation, retesting, or credit math.
Pick the situation that matches you
You should not need to read the whole guide before clicking one of these. Start with the lane that matches your current stage, then come back for the deeper reference only if you still need it.
Jump into a prefilled Manassas action plan based on the result you already have, instead of starting from a generic cost page.
I have not tested yet
Do not price mitigation blind. Get the first number, then decide whether you need monitoring, quotes, or nothing at all.
My result is 2.0-3.9
Usually retest or track first. If the reading keeps showing up, use the local action plan to decide whether pricing makes sense.
My result is 4.0+
This is the EPA action line. Use the local cost page before calling contractors so you know the likely scope, timing, and budget.
I am buying or selling
Turn the reading into a credit or repair number before negotiation starts. This is the faster path than arguing from a generic article.
Already tested once and just want to watch the number trend?
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County Evidence Snapshot
Manassas testing context
Manassas is a higher-priority testing county because the EPA zone signal is high and the page now ties that signal to local housing context.
EPA map signal
Zone 1
County-level predicted indoor screening range, not a home-level test result.
Housing base
14,345
59th percentile among 133 VA counties with data.
Older housing share
66.2%
82th percentile in-state; older homes often need clearer test placement decisions.
Median home value
$393,900
Used as context for whether mitigation is a small maintenance item or a negotiation issue.
Measured Radon Data
Virginia Department of Health Radon Testing Results
2016-2024
Highest measured
37.7 pCi/L
At or above 4.0
Not available
Maximum reported
37.7 pCi/L
Reported tests
19
VDH says the map displays indoor air radon results received by its Radon Program from 2016-2024, using voluntary reports from five major radon test-kit vendors and professional testers after removing duplicates, post-mitigation tests, inappropriate locations, upper-floor tests, and incomplete addresses. VDH suppresses locality averages when fewer than 25 tests are available. RadonVerdict normalized the rendered VDH Tableau table because Tableau Public summary data, crosstab, and workbook export are permission-denied.
RadonVerdict Processed Verdict
Official high-end signal
High-end rank
59th percentile
37.7 pCi/L
4.0+ rank
n/a
Not available at or above 4.0
High-end rank
59th percentile
37.7 pCi/L
Test volume rank
20th percentile
19 reported tests
How to use this county data
Data source
Official county measurements
Virginia values come from VDH-received 2016-2024 indoor air radon results by locality. VDH suppresses averages below 25 tests, so test count and maximum can remain useful even when the average is unavailable.
What the numbers show
High readings have occurred
This source gives the highest measured value, not a county average. Use it to know high readings have happened locally, then verify your own home.
Nearby comparison
Nearby comparison: Closest counties by highest reported reading: Petersburg (37.6 pCi/L) is just lower, and Bedford County (39.3 pCi/L) is just higher.
How this helps
Use this to see that high readings have happened locally, then test the specific property before assuming the county value is typical.
What the data says
Manassas, VA is measurement-backed for 2016-2024.. The high-end signal reaches 37.7 pCi/L.
Manassas, VA sits at the n/a for measured average, n/a for 4.0+ share, 59th percentile for high-end readings, and 20th percentile for test volume among 134 measured counties in the state.
What to do with it
Manassas should be treated as a direct-test county: the official high-end value reaches 37.7 pCi/L, but the source cannot tell whether a specific home is high until that home is tested.
Retest trigger: a 2.0-3.9 pCi/L home result should be confirmed because the official source shows local high-end readings up to 37.7 pCi/L, even though it does not publish a county average here.
Directional confidence (50/100) from Virginia Department of Health based on about 19 reported tests/properties plus high-end county measurement context.
No reading yet
No reading yet: use the official high-end signal as a reason to test the home, not as a substitute for a home result.
2.0-3.9 result
2.0-3.9 pCi/L: confirm with a follow-up or longer-term test because this source proves elevated readings occur locally but does not show the full county distribution.
4.0+ result
4.0+ pCi/L: use the result for mitigation quotes, repair scope, or seller-credit negotiation; the county signal is no longer the deciding input.
Source hierarchy: Virginia Department of Health is used for this county, with EPA zone and Census housing data kept as supporting context. Virginia values come from VDH-received 2016-2024 indoor air radon results by locality. VDH suppresses averages below 25 tests, so test count and maximum can remain useful even when the average is unavailable.
Direct Answer
What radon risk level should homeowners assume in Manassas?
Manassas is currently categorized as EPA Zone 1 (High Risk). Prioritize testing now and prepare for possible mitigation.
| Evidence | Value |
|---|---|
| Area | Manassas, VA |
| EPA Zone | Zone 1 |
| Primary Recommendation | Perform direct radon testing in the lowest livable level |
Your Radon Reading
Enter your home's measured level. This county source publishes a highest reported value, so the slider does not start from a county average.
Warning: Action Required - EPA Threshold Exceeded
At 5.5 pCi/L, this reading is above the EPA action level. Prompt mitigation planning is recommended after confirmatory testing.
Typical mitigation systems reduce radon by 80-99%. See your itemized cost estimate below.
Understanding Radon Levels: Complete Reference
Below 2.0 pCi/L - Lower Concern, Keep Testing
Below both the EPA (4.0) and WHO (2.7) action reference levels. This usually means mitigation is not the next immediate step after a confirmed result. The average outdoor radon level is approximately 0.4 pCi/L, and there is no known risk-free indoor level. Periodic testing is still recommended because levels can change over time due to seasonal variations, changes in home ventilation, or foundation settling.
-4.0
2.0 - 4.0 pCi/L - Elevated, Consider Action
Exceeds the World Health Organization's reference level of 2.7 pCi/L but falls below the US EPA action threshold. The EPA states that homeowners should "consider fixing" homes in this range, especially if the home has a basement used as living space, if children are present, or in connection with a real estate transaction. Practical next step: run a confirmatory long-term test, then compare mitigation quotes if levels remain elevated.
-8.0
4.0 - 8.0 pCi/L - Action Recommended
Exceeds the EPA action level of 4.0 pCi/L. The EPA and Surgeon General strongly recommend mitigation within a few months. At this level, prioritize confirmatory testing and contractor planning. Standard sub-slab depressurization systems typically reduce indoor levels by 80-99%.
Above 8.0 pCi/L - Urgent Action Required
At these levels, the EPA recommends expedited mitigation - ideally within weeks, not months. Occupants should minimize time in lower-level rooms until the system is installed. Use a certified mitigator and request priority scheduling to shorten high-exposure time. Many mitigators offer priority scheduling for homes above 8.0 pCi/L.
Why Radon is a Serious Concern in Manassas
Manassas sits in a geological region with elevated uranium concentrations in the underlying bedrock and soil. As uranium naturally decays, it produces radium, which further decays into radon gas. This gas migrates upward through soil and enters homes through foundation cracks, gaps around pipes, and sump pits.
In Zone 1 counties like Manassas, the EPA predicts indoor screening levels are commonly above 4.0 pCi/L. Individual homes can still vary dramatically - even neighboring houses can differ by a factor of 10 or more. This is why every home needs its own test, regardless of what a neighbor's reading shows.
Factors that amplify radon entry include: basement foundations (more soil contact area), granitic or shale bedrock, tight energy-efficient construction (less natural ventilation), and negative indoor air pressure from HVAC systems, exhaust fans, and dryers.
Radon & Health: What the Science Says
lung cancer
from radon
4.0 pCi/L
Radon is a Class A carcinogen - the same classification as asbestos and tobacco smoke. The National Academy of Sciences estimates that radon causes approximately 21,000 lung cancer deaths annually in the United States, making it the leading environmental cause of cancer death.
Unlike smoking, radon exposure is involuntary and often invisible. There is no safe level of radon - risk increases linearly with exposure. The good news: radon mitigation systems are highly effective, typically reducing indoor levels by 80-99% within hours of activation.
Source: US Environmental Protection Agency, "A Citizen's Guide to Radon" (EPA 402/K-12/002). National Academy of Sciences, Biological Effects of Ionizing Radiation (BEIR VI) Report, 1999.
Step 1: Test Your Home
Testing is the only way to know your home's radon level. Zone data tells you the regional risk, but your home could be significantly higher or lower than the countywide pattern. For most homeowners, the right first purchase is a low-cost short-term test kit.
A digital monitor is a better fit after your first result, for seasonal re-checks, or to keep tracking levels after mitigation.
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Already Know Your Level?
If your test shows 4.0 pCi/L or higher, get an itemized cost estimate specific to Manassas - including regional labor rates and permit requirements.
Get Mitigation Cost Estimate ->VA Radon Regulations
Virginia requires sellers to complete a Residential Property Disclosure Statement covering known defects and environmental hazards including radon.
Virginia does not require specific radon licensing. NRPP or AARST certification is recommended.
How to Test for Radon in Manassas
Buy a Test Kit
Purchase a short-term charcoal test kit online or from a local hardware store. Cost: $15-$30. Place it in the lowest livable level of your home.
Wait 2-7 Days
Keep doors and windows closed (except normal entry/exit) during the test period. Avoid running whole-house fans. Mail the kit to the lab provided.
Read Your Results
If results are below 4.0 pCi/L, re-test every 2 years or use a monitor for ongoing tracking. If above 4.0, use our cost calculator to see mitigation options.
Related Radon Resources for Manassas
Explore Other VA Counties
Official State Resource
Virginia radon program and rules
Use the state program link to verify local radon guidance, disclosure language, and contractor credential expectations before you act on an estimate.
Disclosure rule tracked
Virginia requires sellers to complete a Residential Property Disclosure Statement covering known defects and environmental hazards including radon.
Credential note
Virginia does not require specific radon licensing. NRPP or AARST certification is recommended.
Sources & Methodology
Radon zone classifications for Manassas are sourced from the EPA's Map of Radon Zones, which uses geological surveys, indoor radon measurements, and soil permeability data to assign each county a risk tier.
Disclaimer: Zone data represents county-level screening ranges and cannot predict the radon level in any specific home. Testing is the only reliable method to determine your home's radon concentration. This content is for informational purposes and is not medical advice.
Content review: Source-level retrieval dates
Editorial and Data Transparency
- Author
- RadonVerdict Data Team (Public Data and Cost Modeling)
- Content Review
- Source-level dates shown below
- Data Retrieved At
- 2026-02-24
Primary Sources
- EPA Map of Radon Zones (retrieved 2026-02-21)
- EPA A Citizen's Guide to Radon (retrieved 2026-05-05)
- CDC Environmental Public Health Tracking - Radon Testing (retrieved 2026-05-05)
- Virginia Department of Health Radon Testing Results (retrieved 2026-05-06)
- Official VA radon program
- US Census Bureau, 2018-2022 American Community Survey 5-Year Estimates (retrieved 2026-02-24)