Can You Test for Radon With the Windows Open?

Posted in Radon Testing, on September 10, 2026

At SafeAir, one of the common questions we get about radon testing is whether or not the windows need to be closed during testing. They do! But that doesn't mean your house has to be closed up for the duration of testing. In this article, we'll explain how radon detection works, where tests need to be placed, and how to avoid disturbing the results. With over a decade of experience performing radon tests and air quality testing, the SafeAir team has learned a few things we're happy to share.

How Radon Testing Works

When you book a radon test with us, we'll come to your home and perform a brief inspection of your lower levels. During this inspection, we're assessing the best area to install the device for a 3-6 month period (more on this later). The device itself is similar in scale to a fire alarm, but it makes no noise, and just passively tests the air. When your testing period is over, we uninstall the device and send it to a lab for analysis.

The Importance of Test Placement

Accurate test placement for radon detection is critical, and it's why we recommend having a professional radon test instead of a DIY test. Radon tends to enter homes through the lowest level, which in Ontario is the basement. The layout, use, finishing, and placement of windows and doors can all affect where a testing device goes.

Normal Occupancy

Another critical element of accurate radon testing is normal occupancy. During the testing period, we want you to live as normally as possible, mimicking the conditions that exist when you may be exposed. This is why windows open or closed makes less of a difference. We'll place the test so that any external openings don't skew the results and reflect how air and people move around your home. We're aiming for real-world conditions, not a perfectly sealed home.

HVAC Operation

Many different elements affect how radon gas moves through your home and why, or where, it collects. Another common question we field is about the HVAC, and how running the furnace or air conditioning may disturb testing results. This is another element we'll assess during our placement visit, because each home is unique, but rest assured, you'll be able to use your HVAC as usual during the testing period.

Why Book Radon Testing?

Radon gas is one of the leading causes of lung cancer in Canadians. Because it's invisible, scentless, and leaves no trace, professional radon testing is the only way to know if your home is affected. If you want to learn more about radon's effect on your health, please read our blog What High Radon Means For Your Health. And when you're ready to book, so are we! SafeAir's friendly team can help answer any follow-up questions about indoor air quality or radon testing by phone or email — reach out to us today.