Long-term radon testing in Calgary

What exactly is a long-term radon test?

It is a single measurement stretched over a season instead of a weekend. Health Canada's measurement guide asks for a test lasting between three and twelve months, with 91 days as the floorsource. That guide does not recommend test periods shorter than 91 dayssource. The detector does not report as it goes. It accumulates exposure quietly, and the laboratory later converts what it collected into an average concentration for the dates written on its paperwork.

That design has a consequence some people find frustrating: for the whole season there is nothing to look at. No display, no app, no early hint. The trade is deliberate. A device with nothing to read is a device nobody nudges toward the window, unplugs after a worrying evening or keeps checking. Health Canada's position is that every home should be tested, wherever it stands and whatever kind of building it issource.

What does a full season of measuring capture that a few days miss?

The rises and the falls together. Indoor radon is not steady. It moves with outdoor temperature, wind, barometric pressure, and how hard the furnace and the exhaust fans are working. A short-term test typically lasts between two and seven dayssource, so it can land entirely inside a calm spell or entirely inside a stormy one. A detector that stays out for a season sees many of each, and its average is not hostage to any particular week.

Soil gas is drawn indoors because the air pressure inside a house is usually lower than the pressure in the ground, and the stack effect strengthens that pull during the cold monthssource. Those pressure differences are exactly what shifts from one day to the next. A long test does not try to predict them. It stays put until enough of them have passed through the record.

The guideline is written in matching terms. Canada's 200 Bq/m³ figure refers to an annual average, and corrective action is recommended when a home's average sits above itsource. Holding a weekend reading up against an annual figure compares two different kinds of number. A seasonal average is a far closer match.

Which months count toward the test in Calgary?

The furnace months. At least 91 days of the test should sit inside the heating season, the stretch when windows stay shut and indoor radon tends to be at its highestsource. Health Canada's advice, as quoted in the Canadian mitigation standard, is to test for at least three months, ideally between October and Aprilsource.

In practical terms, a detector set out around Thanksgiving and picked up once the deep cold has come and gone has done its job. One set out in spring is not wasted, but it has to remain until it has gathered its share of closed-window weather. That is why the calendar comes up before booking: the start date decides the earliest sensible end date.

Chinooks deserve a mention, because Calgarians ask about them. A warm, windy couple of days in January changes the pressure around the house and may tempt someone to crack a window. Over a season that is a small slice of the record, and it belongs there. The test is meant to reflect the house as it is really lived in, not an idealized sealed box.

How is the detector placed on the first visit?

By walking the lowest level you use and settling on one room. Health Canada's criteria are a room occupied for four or more hours a day on the lowest lived-in level, with the device about 30 cm or more off the floor and kept away from walls, kitchens, bathrooms, laundry rooms, vents, heat sources, direct sun and electronicssource.

Those criteria rule out more of a basement than people expect. The mechanical room fails on vents and heat. The bar counter beside the mini fridge fails on electronics. The window ledge fails on sunlight and drafts. What is usually left is a bookshelf, a nightstand or the top of a dresser in a bedroom, den or playroom. Where the lower level is storage and nothing else, the detector moves up a floor, because the measurement follows people and not concrete.

The placement visit is done by Plinio Neto, holder of the C-NRPP Radon Measurement Professional certification (CRT-202965). Health Canada recommends professionals certified through the Canadian National Radon Proficiency Programsource, and his entry is open to anyone in the public C-NRPP listing of certified individuals.

What is written down at the start, and why does it matter?

Enough to let a stranger trust the number years from now. A result without paperwork is a figure on a page; with its record attached, it is evidence. A proper deployment sheet records the following at placement:

• The detector's serial number, copied from the device itself.
• The address, the floor and the name of the room.
• The exact position: which piece of furniture, and roughly how high off the floor.
• The date and time the detector was opened to the air.
• Who placed it, with their certification number.
• Anything unusual about the house that season, such as renovation work or a long absence.

Ask for a copy. The original travels with the detector, because the laboratory needs the opening and closing dates to turn total exposure into an average concentration. A wrong date produces a wrong result, which is why this dull step gets real care.

What should the household do while the detector is out?

Nothing different. Heat the house the way you always do, run the ventilation the way you always do, and take the holiday you had planned. The only requests are negative ones. Please do not cover the detector, wipe it with a wet cloth, tuck it into a cupboard when guests arrive or let a curious child carry it upstairs. If painters or flooring installers are due in that room, tell us beforehand and not afterwards.

Life sometimes interferes anyway. A flooded basement, a furnace that fails for a stretch, a renovation that opens the foundation: each changes the conditions the test was supposed to represent. Jot down the dates. In some cases the result still stands with a caveat attached, and in others the honest answer is to run the test again.

How does the detector reach the laboratory?

Sealed, labelled and without delay. When the exposure period ends, the detector is closed inside the pouch or bag supplied with it, which stops it recording. The closing date and time go on the sheet. Then it is shipped together with its paperwork. Speed matters mainly when the seal is poor: an unsealed detector keeps counting wherever it sits, including in a mailbox or on a car seat.

At the laboratory, the film inside an alpha track detector is chemically treated so the microscopic marks left by radon decay become visible, and those marks are counted. The count and the length of exposure together give the average. You never handle any of that. Your part is making sure the dates are right.

How do alpha track detectors and digital monitors differ?

One produces a laboratory record and the other a running display, and they serve slightly different needs. For long-term measurement, Health Canada recommends two passive devices, the alpha track detector and the electret ion chamber, and notes that electronic radon monitors are in use as wellsource.

C-NRPP has tested consumer-grade electronic monitors and publishes the models it approves; it notes that they cannot be professionally calibrated, are not approved for use by measurement professionals, and should be left in place for at least three monthssource. The last point is worth underlining. The device with a screen needs the same patience as the device without one. A daily figure on a phone is interesting, but only the long average is comparable with the guideline. Our page on test kits and home monitors sold in Calgary goes through the choices, and the guide on how accurate home kits are looks at where errors creep in.

What does the written report show?

One average, plus the context needed to rely on it. A complete long-term report lists:

• The average concentration in Bq/m³ over the test period.
• The opening and closing dates.
• The address, floor and room.
• The detector type and serial number.
• The laboratory's name and the date of analysis.
• The name and certification number of the person who placed the device.
• Notes on anything that may have disturbed the test.
• A plain-language reading of the result against the Canadian guideline.

The reading itself is short. Above 200 Bq/m³, Health Canada recommends bringing the level down within a year, faster as the number climbs, and as low as reasonably achievablesource. That recommendation applies above the guideline. Below it the decision rests with you, bearing in mind that no level is considered risk-free and lower is better. The page on how Canadian radon guidelines sort results into ranges sets out each band.

Some reports give the result in picocuries per litre. One pCi/L equals 37 Bq/m³source, and the unit converter does the arithmetic. If your average is over the line, the next reading is how radon mitigation is done in Calgary houses, and the Calgary mitigation cost breakdown covers budgeting.

Why does a long average suit Calgary homes in particular?

Because local results crowd close to the line. The Cross-Canada Survey of Radon Exposure reported that about 1 in 6 houses in the Calgary area (15.5%) were at or above 200 Bq/m³, that a further 36.9% fell between 100 and 199 Bq/m³, and that the area average was 102.5 Bq/m³source. On our reading of those figures, a large share of homes here sit in the range where a snapshot could easily fall on the wrong side of the guideline. For those houses, a seasonal average is the difference between a decision and a guess.

Borrowing a figure from across the fence does not help. Radon differs from house to house, even between similar homes side by side, and testing is the only way to know one particular home's levelsource. Construction era is no shortcut either. In a 2017 southern Alberta study, homes built in 1992 or later averaged 31.5% more radon than older ones, 142 against 108 Bq/m³source. A recent build in a new suburb deserves the same season-long test as a mid-century bungalow near the core.

Developed lower levels change who is exposed. When a basement holds bedrooms, a home office or a rental unit, the room that qualifies for the detector is downstairs, and that is where it goes. For a home with a separate tenant below, see radon in Calgary basement suites.

What does the fee cover, and what are the alternatives?

A quote for a professionally placed test should name the detector, the placement visit, the deployment record, the laboratory's analysis and the written report. If you would sooner do the placing and mailing yourself, a mail-in kit follows the identical protocol, and our guide on testing a house for radon step by step walks through it.

A sale changes the timing but not the method. For what to do around a purchase or a listing, see radon testing during a Calgary home sale. For the wider comparison of methods, the parent page on radon testing services in Calgary is the place to start. And a long-term test is not a one-time event for homes that end up with a system. Health Canada recommends testing again after a mitigation system goes in, every five years while it is running, and after renovations that alter the structure or ventilationsource.