How Do I Test For Radon?

Since radon is an odorless, colorless radioactive gas, testing using special equipment is the only way to find out if you have a radon problem in your home or business.


There are two methods used to test for the presence of radon: passive tests, and short-term, continuous monitoring.

Passive tests use a filtered packet containing charcoal to passive collect the byproduct of decaying radon over the course of 3-5 days. Those packets are then mailed to a lab, with results returned by mail or fax.

The other method used to test for radon is short-term, continuous monitoring. This method uses an electrical monitor that detects the byproduct of radon decay over the course of 48 hours.

In addition to monitoring the radioactive decay particles, the device also measures the ambient air temperature, humidity, and air pressure. These factors can affect the level of radon being drawn from the soil into the building.

The state of Minnesota strongly recommends that any testing done for the purpose of a real estate transaction be conducted by a certified radon professional, using continuous monitoring equipment approved by the National Radon Proficiency Program (NRPP) such as the Radalink Air Cat pictured above.

The EPA recommends that testing device(s) be placed in the lowest level of the home or business suitable for occupancy. This means testing in the lowest level (such as a basement) which a home owner could use as a living space.

The test must be conducted under closed-building conditions, which means keeping all windows closed, keeping exterior doors closed except for normal entry and exit, and not operating fans or other machines which bring in air from outside.  Fans that are part of a radon-reduction system or small exhaust fans operating for only short periods of time may run during the test.

It is also vital that no one touch, tamper with or move the monitor. Efforts to tamper with the monitor or alter the indoor environment will be recorded by internal sensors. Willfully tampering with a radon test is prohibited by law and may result in civil penalties.