A radon test needs a sensible spot to give you useful information. In most homes, that means testing the lowest level where people spend time or could reasonably use the space. The device also needs room to collect air without interference from drafts, moisture, or everyday activity. Whether you use a test kit or hire a professional, follow the test instructions closely. A well-placed test is a practical first step toward understanding your home's radon level.
Choose the Right Level
Test the lowest lived-in level of the home, such as a first-floor living area or a finished basement used regularly. If the basement is unfinished but could be converted into a bedroom, playroom, or other usable space, testing there can help assess that potential living area. Radon can vary from one floor to another, so a result from an upstairs room may not represent conditions on the lowest level.
If no one uses the basement and it is not suitable for regular occupancy, test the lowest level where people spend time. In a home without a basement, that is usually the first floor. For a home with several separate foundation sections or additions, ask a qualified radon professional whether more than one test is appropriate.
Pick a Suitable Room
Place the device in a room that is used regularly, such as a living room, family room, or bedroom. Set it on a stable surface, following the height and placement directions supplied with the kit or by the testing professional. Keep it away from exterior doors, windows, and vents, where moving air can affect the sample.
Avoid kitchens, bathrooms, laundry rooms, and other places with frequent humidity, strong odors, or changing airflow. Do not place a test in a closet, near a fan, beside a heating or cooling register, or in direct sunlight. These spots may not reflect the air people usually breathe and can interfere with accurate measurement.
Keep Conditions Consistent
Short-term tests commonly require the home to remain closed up for a specified period. Follow the device instructions about windows, exterior doors, and ventilation before and during testing. Normal entry and exit are usually expected, but avoid leaving windows open or running equipment in a way the instructions prohibit.
Everyday changes can influence a result. Weather, wind, heating and cooling systems, open windows, and changes in how the home is occupied may affect radon readings. Record unusual conditions, such as major storms or a ventilation change, and tell the testing provider if you are unsure whether they affect the test. Do not move the device once testing begins.
Test Again When Needed
Radon levels can differ over time, so one reading is a snapshot rather than a permanent guarantee. If a test shows an elevated level, confirm the result with a follow-up test according to current public health guidance or advice from a qualified radon professional. Use the appropriate testing method and placement for the follow-up rather than assuming a result from another room is directly comparable.
Consider testing again after renovations, changes to the foundation, or alterations to ventilation or heating systems, especially if those changes affect the lowest level. If you are buying, selling, or preparing a lower-level space for regular use, check applicable guidance and arrange testing that fits the situation. Keep the report and note where and when the test took place.
For a useful radon result, test the lowest level people use or could reasonably occupy, and place the device in a stable, regularly used room away from drafts and moisture. Follow the test instructions and note anything unusual. If you want help choosing a test location or interpreting a result, contact a qualified radon testing professional.