Conditions That Affect Radon Tests

Radon is a naturally occurring radioactive gas. It is formed during the breakdown of the uranium found in soil and rocks. Radon is invisible and does not have a taste or odor. Consistent exposure to high levels of radon may lead to lung cancer. To properly detect radon a specialized test must be performed. These tests are sensitive to a variety of conditions and must be administered appropriately to get an accurate reading.


A change in the placement of a radon detector may skew test results. All people living in the home should agree not to disturb the equipment. The equipment should be placed on the lowest level of the property used as a living space. It should be in a spot where it will not be disturbed. The use of a motion detector can help determine if a test has been moved.

Weather Conditions

Changes in barometric pressure may alter radon test results. Do not test for radon during severe storms or when high winds are predicted.

Open doors and windows

An accurate radon test requires closed house conditions. All windows and doors, with the exception of normal entrances and exits, should be closed and remain closed for the duration of the test. Opening and closing doors and windows will change the ventilation and temperature in the home and temporarily change radon level readings. For a short-term test of less than four days, closed conditions should begin at least 12 hours before starting the test.

Household equipment

Changes in air pressure can be caused by window or attic fans, active fireplaces or wood-burning stoves. Do not use any of this equipment, unless the wood-burning stove is a primary heat source, while the radon test is conducted.


Test kits should be raised at least 20 inches off the floor and a foot from outside walls in the lowest living level of the home. No other objects should be within 4 inches of the test kit. Tests should not be conducted in a sunny, drafty or humid area.