Not all radon tests are created equal. The length of time a test runs has a big impact on how accurately it reflects your true exposure. For Calgary homeowners, choosing the right type of test depends on why you are testing and how quickly you need an answer. Here is how to decide.
Radon levels in a home are not constant. They rise and fall with the weather, the season, how often doors open, whether the furnace is running, and even barometric pressure. A reading taken over two days captures a snapshot; a reading taken over months captures the average you actually breathe. Because health risk is tied to long-term average exposure, the duration of your test directly affects how meaningful the result is.
A long-term test runs for a minimum of 90 days, and Health Canada recommends this as the most accurate way to assess your home. Ideally it is conducted during the heating season — roughly fall through early spring — when Calgary homes are closed up and radon tends to be highest.
By averaging across many weeks, a long-term test smooths out the daily and weekly swings that can mislead a short test. It reflects your real annual exposure far better than any brief measurement. For any homeowner who simply wants to know whether their family is safe, this is the recommended approach.
A short-term test runs anywhere from about 48 hours to a week, often using a continuous radon monitor that logs readings hour by hour. It trades some accuracy for speed.
The most common reason for a short-term test is a real estate transaction. Condition periods in Alberta home sales are usually too short to accommodate a 90-day test, so a calibrated continuous monitor provides actionable data within days. Short-term tests are also useful as a quick screen — if a 48-hour test comes back very high, you know mitigation is needed without waiting months.
Because radon fluctuates, a short test can read higher or lower than your true average. Closed-house conditions must be maintained for the entire test (windows and exterior doors kept shut except for normal entry) or the result is invalid. A single short test in isolation should be interpreted with care.
A common and sensible strategy is to start with a short-term test for speed, then confirm borderline or important results with a long-term test. If a quick test reads dramatically above the 200 Bq/m³ guideline, you can move toward mitigation immediately. If it sits near the guideline, a follow-up long-term test removes the uncertainty before you decide.
Long-term tests typically use passive detectors like alpha-track devices that are returned to a lab for analysis. Short-term real estate testing usually relies on continuous radon monitors that a professional places, retrieves, and documents. For results you can act on or hand to a buyer, the device should be appropriate to the purpose and, ideally, placed by a C-NRPP certified professional.
If you are testing your own home and have the time, choose a long-term test during the heating season for the truest picture. If you are buying or selling and need data fast, a professional short-term continuous monitor is the right tool. Onyx Radon offers both, and our C-NRPP certified team will help you choose the test that matches your situation — so the number you get is one you can actually trust.
Certified testing & mitigation in Calgary. Request a free quote.
Request a free quote