Basic EPA Radon Testing Protocol for Homes

The 1993 EPA radon testing protocol has been replaced by the 2010 ANSI/AARST Standard: Protocol for Conducting Radon and Radon Decay Product Measurements in Multifamily Buildings (MAMF-2010) which is largely based on the EPA’s earlier protocols. What I want to point out in this article is the location for testing and not testing radon in homes. Many times I have seen where radon tests were improperly placed which most likely caused inaccurate or unreliable test results either higher or lower than if properly tested. Please note the highlighted sections below.

The following is copied from page 9 of the EPA Booklet “Protocols For Radon And Radon Decay Product Measurements In Homes”, printed in May, 1993.


EPA Protocols For Radon Measurements in Homes

2.2 Measurement Location

Short-term or long-term measurements should be made in the lowest lived-in level of the house. The following criteria should be used to select the location of the detectors within a room on this level:

The measurements should be made in the lowest level which contains a room that is used regularly. Test areas include family rooms, living rooms, dens, playrooms, and bedrooms. A bedroom on the lower level may be a good choice, because most people generally spend more time in their bedrooms than in any other room in the house (Chapin 1974, Moeller and Underhill 1976, Szalai 1972). If there are children in the home, it may be appropriate to measure the radon concentration in their bedrooms or in other areas where they spend a lot of time, such as a playroom, that are situated in the lowest levels of the home.

In general, measurements should not be made in kitchens, laundry rooms, or bathrooms. The measurements should not be made in a kitchen because of the likelihood that an exhaust fan system and changes in small, airborne particles (caused by cooking) may affect the stability of WL measurements. Measurements should not be made in a bathroom because relatively little time is spent in a bathroom, because high humidities may affect the sensitivity of some detectors, and because of the likelihood that use of a fan may temporarily alter radon or decay product levels.

Although radon in water may be a contributor to the concentration of airborne radon, radon in air should be measured before any diagnostic radon-in-water measurements are made. (Diagnostic measurements may be made in the bathroom; however, such diagnostic measurements should not be used to determine the need for mitigation.)

A position should be selected where the detector will not be disturbed during the measurement period and where there is adequate room for the device.

The measurement should not be made near drafts caused by heating, ventilating and air conditioning vents, doors, fans, and windows. Locations near heat, such as on appliances, near fireplaces or in direct sunlight, and areas of high humidity should be avoided.

• Because some detectors are sensitive to increased air motion, fans should not be operated in the test area. Forced air heating or cooling systems should not have the fan operating continuously unless it is a permanent setting.

• The measurement location should not be within 90 centimeters (three feet) of the doors and windows or other potential openings to the outdoors. If there are no doors or windows to the outdoors, the measurement should not be within 30 centimeters (one foot) of the exterior wall of the building.

The detector should be at least 50 centimeters (20 inches) from the floor, and at least 10 centimeters (four inches) from other objects. For those detectors that may be suspended, an optimal height is in the general breathing zone, such as two to 2.5 meters (about six to eight feet) from the floor. Sound judgment is required as to what space actually constitutes a room. Measurements made in closets, cupboards, sumps, crawl spaces, or nooks within the foundation should not be used as a representative measurement.

The Most Common Violations of EPA Radon Testing Protocol:

  • Setting radon testing monitors on floors in empty basements because there is nothing to sit it on. They should get a tripod, box or chair to place meter or test kit on so that it meets the minimum required height of 20 inches above the floor.
  • Setting radon test on window sill of outside wall (should be placed at least 12 inches from exterior wall, and 3 feet from outside windows or doors. Again this usually happens when there is nothing convenient or better to sit the radon monitor on, this usually occurs in an empty home in a finished basement.
  • The radon monitor or test kit is placed underneath or near a heat/ac vent. Usually due to careless placement, not noticing the HVAC vents. This could greatly effect the test.
  • Sometimes home inspectors will conduct test at opening to a crawl space or next to a sump pit. Both of these locations can be drafty, and damp or wet. A crawl space is certainly not a living area. High humidities may affect the sensitivity of some
    detectors, and drafts will also affect readings.
  • Some inspectors will place radon test kits in basements with dirt floors, these spaces are not suitable for living area and should be treated like crawl spaces.

Get Your Own Copy of EPA Protocols for Radon Measurements in Homes

The “Protocols for Radon And Radon Decay Product Measurements in Homes” booklet is available here as a downloadable PDF Version (47 pp, 674 K) | EPA 402-R-92-003, May 1993. This booklet gives the U.S. EPA’s technical guidance on how to measure radon concentrations in homes. The purpose EPA Radon Testing Protocol is for accurate testing of radon to determine if the levels are high enough to require remedial action which usually means a radon mitigation system would need to be installed. I refer you to these topics as discussed in the following EPA publications:  A Citizen’s Guide to Radon, and the Home Buyer’s and Seller’s Guide to Radon.