Testing your home
How do I test, and how do I know the result is real?
Testing is the one step in this entire subject where a homeowner controls the quality of the evidence. Almost every disputed radon result on record failed on conditions rather than on the device.
The order below matters. Choosing a method before knowing the purpose produces a valid number that answers the wrong question — a two-day charcoal kit is fine for a first look and is the wrong instrument for a contract deadline.
Who this is for. Someone who has decided to measure, or who has a result in hand and is unsure whether to trust it.
The reading order
6 steps, 14 resources. Nothing below is written here — every link goes to the page that holds the substance, and the note under each one says what it adds at that point in the sequence. A hub that restated its own links would just be competing with them.
First, whether to test at all
There is a real answer to this, and it depends on what has already been measured in the house and what you are about to do with the property.
- Should I test? Tool
Works through prior results, transaction context, and what has changed in the house since the last measurement. Publishes every rule it applies.
- How testing works Guide
What the devices are actually doing. Read this before choosing between them, not after.
- Should I test? Tool
Then which method
Duration and evidentiary strength are separate axes, and only one class of device documents the conditions it ran under.
- Monitors vs short-term tests Guide
The trade-off in full: cost, duration, and whether the record can defend itself if challenged.
- Radon Testing Method Comparison Dataset Dataset
The same comparison as structured data, so you can sort by the axis that matters for your purpose.
- Testing methods by duration and evidence Diagram
One picture of the two axes. Useful when explaining to someone else why a kit is not always sufficient.
- Continuous monitors Newsroom
What has genuinely changed in monitor hardware, separated from what is marketing on the same devices.
- Monitors vs short-term tests Guide
Run it so the result holds up
Closed-building conditions and placement are the whole game. These two lists exist to be printed and left where the people who could invalidate the test will see them.
- Before testing Checklist
Everything that happens in the twelve hours before the device starts counting, including who needs to be told what.
- During testing Checklist
Mostly a list of things not to do. In an occupied house that is genuinely the hard part.
- Before testing Checklist
Read the result
A number becomes a decision through a chain of reasoning that should be visible rather than assumed.
- What does my result mean? Tool
Takes your figure, duration, and device and returns what that combination supports — not a verdict dressed up as one.
- Weather effects Guide
Why the same house reads differently in February and July, and what that does to a single short measurement.
- What does my result mean? Tool
When the number looks wrong
A surprising result has a small number of likely explanations, and they are worth working through in order before spending money.
- False positives Guide
The causes ranked by how often they actually explain a surprising figure.
- Should I retest? Tool
Whether your specific situation warrants a second measurement, and what kind it should be.
- When to retest Guide
The standing cadence, separate from the one-off question of whether this particular result is suspect.
- False positives Guide
Fitting a test inside a deadline
Contract windows do not extend for laboratory turnaround. This is where testing becomes a scheduling problem.
- Build a testing timeline Tool
Counts backwards from a closing or inspection deadline and shows which method still fits.
- Build a testing timeline Tool
What you should be able to do afterwards
- Choose a device that matches the purpose, not just the budget.
- Set up conditions that would survive a challenge from the other side of a transaction.
- Tell the difference between a result you should act on and one you should repeat.
- Work out whether a test still fits the days you have left.
Related hubs
- Understanding radon — The mechanism first. Everything else on this site assumes you have it.
- Mitigation systems — A pipe and a fan is not a design. This is the difference.
- Buying and selling — A transaction turns radon into a scheduling problem with a deadline.
- All nine hubs — the full learning centre.
Confidence and limits of this page
Every decision resource on this platform states its own boundaries. This is not a disclaimer — it is the part of this hub you should read before relying on it.
- What we knowClaims on this page we stand behind, each traceable to an approved source or to observable structure.
- Closed-building conditions and device placement are specified in published testing guidance, and departures from them are the most common reason a result is challenged.
- Short-term and long-term measurements answer different questions, and duration is part of what a result means rather than an inconvenience attached to it.
- Weather and season measurably affect indoor readings in the same house, which is why guidance treats a single short measurement as a screening step.
- What we do not knowQuestions you may reasonably have that this page does not answer.
- How far any individual short measurement sits from that house annual average, which cannot be recovered from the short measurement itself.
- Whether a given laboratory or device met its stated precision on your particular sample, which only duplicate measurements would show.
- What research would settle itWhat it would actually take to answer the above — naming it is the difference between honesty and hedging.
- Paired short and long measurements in the same houses under documented conditions, which would quantify how often a screening result changes the decision.
- Device-to-device duplicates across a range of humidity and temperature, which is the evidence that would let anyone state real-world precision rather than laboratory precision.
- What we do not claimClaims you might expect to find here and will not, with the reason.
- We do not claim any device brand or laboratory is more accurate than another, because we hold no comparison measurements and a ranking without them would be invented.
- We do not claim a specific correction factor for season or weather, because applying one to a single house would imply a precision that does not exist.
- What we cannot independently verifyFacts this page relies on that we could not confirm ourselves.
- Whether a given laboratory currently holds the credential it advertises, which only the issuing authority can confirm at the moment you ask.
- The present content of the cited guidance documents, for the network reason stated in our methodology.
Sources
- U.S. EPA — A Citizen’s Guide to Radon
- U.S. EPA — Radon
- IEMA-OHS — Illinois Emergency Management Agency and Office of Homeland Security — Radon Program
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