Page 34 - Summer2011

There are many options for testing radon in homes. The devices below are used for short term and long term testing. If you are considering doing a radon test of your home you should only hire a licensed radon testing firm. The testing firm should only test for radon and not do

mitigation. This is considered a conflict of interest. Charcoal canisters are the most widely used due to the fact in most cases the testing company only has licensed technicians on staff. The canisters are sent out to a licensed testing lab for analyses. To analyze devices the testing company must have a licensed as a testing business. LHI Analytical is one of four inspection firms in NJ to be licensed as a testing business.

For this method, an airtight container with activated charcoal is opened in the area to be sampled and radon in the air adsorbs onto the charcoal granules. At the end of the sampling period, the container is sealed and may be sent to a laboratory for analysis.

The gamma decay from the radon adsorbed to the charcoal is counted on a scintillation detector and a calculation based on calibration information is used to calculate the radon concentration at the sample site. Charcoal adsorption detectors, depending on design, are deployed from 2 to 7 days. Because charcoal allows continual adsorption and desorption of radon, the method does not give a true integrated measurement over the exposure time. Use of a diffusion barrier over the charcoal reduces the effects of drafts and high humidity.

For this method, the detector is a small piece of special plastic or film inside a small container. Air being tested diffuses through a filter covering a hole in the container. When alpha particles from radon and its decay products strike the detector, they cause damage tracks. At the end of

the test the container is sealed and returned to a laboratory for reading.

The plastic or film detector is treated to enhance the damage tracks and then the tracks over a predetermined area are counted using a microscope or optical reader. The number of tracks per area counted is used to

calculate the radon concentration of the site tested. Exposure of alpha track detectors is usually 3 to 12 months, but because they are true integrating devices, alpha track detectors may be exposed for shorter lengths of time when they are measuring higher radon concentrations.