Testing after your radon system is installed

Why test again when the system is already running?

Because a running fan proves suction, not a result. The gauge on the pipe and the radon in the room are two different measurements, and only the second one was the reason for the work.

A U-tube manometer on the pipe indicates that the mitigation system is working, with the higher liquid level on one side showing the pressure difference the fan createssource. That is useful every day of the system's life. It still says nothing about what you are breathing.

Health Canada says a radon reduction system reduces radon by more than 80% in most homessource. "Most" is the honest word in that sentence. Soil, slab and layout differ from one address to the next, and nobody can state the final number for your house in advance. Health Canada's measurement guide recommends a new test once a system has been installedsource. A system without a follow-up measurement is unfinished work.

What are the two steps of confirmation?

A short reading by the installer, then a long-term test by you. Each answers a different question, and neither can stand in for the other.

The short reading exists to catch an obvious problem early. If the number has barely moved, that is known before the installer has forgotten the house, and the system can be looked at again while the details are fresh. A sharp fall in the short reading does not settle the result; the long-term test does.

For radon work, Health Canada recommends hiring a professional certified by the Canadian National Radon Proficiency Program, known as C-NRPPsource. The verification reading on systems installed through Calgary Radon Pro is taken by Plinio Neto, who holds the C-NRPP Radon Measurement Professional certification (CRT-202965) in his own name. It can be confirmed in the public C-NRPP listing.

Why is the long-term test done with an independent laboratory kit?

So that the person who built the system is not the person who marks it. The kit comes from a laboratory, you set it out, you mail it back, and the report is addressed to you.

An installer has an obvious interest in a low number. That does not make installers dishonest. It does mean the cleanest record is one the installer never handled.

For long-term tests Health Canada recommends two types of passive device, alpha track detectors and electret ion chambers, and notes that electronic radon monitors are also usedsource. A mail-in kit of the alpha track type needs no power, makes no sound and has nothing to read. The analysis is done after it reaches the laboratory.

Why is the short reading not enough?

Because radon rises and falls with weather, wind and how the house is used, and a few days capture only a slice of that. Short-term radon tests typically last between 2 and 7 dayssource. Health Canada does not recommend testing for periods shorter than 91 dayssource.

Both statements hold at once. The short reading is a check on the equipment. It is not the measurement that Health Canada's guideline is written for. That measurement lasts 3 to 12 monthssource, and its result is the one to compare with the guideline, to quote to a buyer and to keep.

Where and when should I place the long-term kit?

On the lowest level where people spend time, during the heating season. Putting it where the original test sat lets you compare the two results directly.

Health Canada's instructions call for a regularly occupied room, used 4 or more hours a day, on the lowest lived-in level, with the detector about 30 cm or more from the floor and away from walls, kitchens, bathrooms, laundry rooms, vents, heat sources, direct sun and electronicssource.

One extra point applies after mitigation. Keep the detector out of the mechanical room where the fan and pipe are. You are measuring the air people live in, not the air beside the equipment.

According to Health Canada, at least 91 days of the test should fall in the heating season, when closed windows mean indoor radon tends to be highestsource. The Canadian mitigation standard, citing Health Canada, puts the ideal window between October and Aprilsource. A system installed in autumn can go straight into its confirmation test. In our own view, which follows from that seasonal advice and is not a separate Health Canada instruction, a system installed in spring is better confirmed when the cold returns. In the meantime the short reading and the gauge are what you have. The method is the same as for any long-term radon test in a Calgary home, and our guide to winter radon testing covers the seasonal detail.

What result should I expect?

A lower level than the one measured before the work is the aim. How far it falls depends on the house, so no figure is promised here or in a quote.

Health Canada's position is that levels should be reduced as low as reasonably achievablesource. That is a direction, not a target number. Its recommendation to take corrective action applies when the annual average is above 200 Bq/m³source. Under that figure, what you do next is your decision, bearing in mind that lower is better and that no level is considered risk-free.

When the report arrives, read the number, the dates and the location on it, and check that they match what you did. The radon test result checker puts a figure in context, and the page on radon levels and guidelines explains where the Canadian number comes from.

What happens if the level has not dropped enough?

The first step is for the installer to look at the system again. What the installer will do in that case, and who pays for it, should be written in the quote, as explained below the table. A disappointing result is information about the system.

Before you sign for a system, ask what the quote says about this situation. A sound quote states in writing what the installer will do if the confirmation test comes back above the guideline, and who pays for it. We would sooner you asked that question of us than assumed the answer.

Where the work was done by someone else and they cannot be reached, the starting point is an inspection of the existing radon system. Open sumps and exposed soil are covered under sump pit mitigation and crawl space mitigation.

Can my own electronic monitor do the confirmation?

It can follow the trend. It should not be the record. C-NRPP has tested consumer-grade electronic radon monitors and publishes the models it approves, while noting that they cannot be professionally calibrated and are not approved for use by radon measurement professionals; it advises leaving one in place for at least 3 monthssource.

A monitor earns its place after the confirmation test is finished. It will show you the daily swings, and it will show you quickly if something changes. Set it in the room where the laboratory kit sat. If its long average drifts upward, look at the manometer first. Whether to start a new laboratory test at that point is your decision; doing so is our own suggestion and not an interval set by Health Canada.

How often should a home with a system be retested?

On a fixed interval, and after work that changes the building. Health Canada recommends retesting homes with active mitigation systems every 5 years, and testing again after any renovation that affects the structure or ventilation of the homesource.

The renovation half of that advice is the one owners miss. Developing a basement, cutting the slab for plumbing, building an addition or changing how the house is ventilated can each alter how soil gas reaches the indoor air. None of those jobs involves the radon system directly, which is why nobody thinks to test afterwards. Health Canada's list ends there. Testing again after a fan replacement or a significant repair is our own suggestion, and it is not part of that advice.

A sale brings advice of its own. Health Canada's advice for sellers is to test, and mitigate if necessary, before selling, so that a low level can be presented as a feature of the homesource. Its advice for buyers is to run a long-term test once they have moved insource. A recent laboratory report makes the first of those easy, and a system in the house does not excuse a buyer from the second.

Why does the heating season matter so much in Calgary?

Because winter is when a Calgary house draws hardest on the soil beneath it, so winter is when a system is properly tested.

Health Canada explains that radon is drawn indoors because indoor air pressure is usually lower than the pressure in the soil, and that the stack effect increases entry in cold monthssource. A confirmation test run only through a mild summer, with windows open, shows the system on its easiest days.

The local numbers explain why the confirmation is worth doing with care. The Cross-Canada Survey of Radon Exposure found about 1 in 6 houses in the Calgary area (15.5%) at or above 200 Bq/m³, with an average of 102.5 Bq/m³source. A house that needed a system began in the upper part of that picture. The long-term report is the only document that shows where it sits now.

What records should I keep?

Everything that lets a stranger follow the story: the level before, what was installed, and the level after. Keep it in one folder, on paper or as scans.

• The original test report that led to the work.
• The invoice, with the installer's name and certification number.
• The manometer reading at start-up, if it was recorded.
• The installer's short verification reading.
• The laboratory report from the long-term confirmation test, with its dates and the room used.
• Every later retest, and a note of any renovation or repair in between.

The folder is worth more than it looks. It answers a buyer's questions in a minute, and it gives the next installer a baseline if the system ever needs attention. For the system side of the story, start at radon mitigation systems for Calgary homes. For what the work costs, see radon mitigation prices in Calgary. If you have a report in hand and are unsure what it says, how to read radon test results goes through one line by line.