Special moist, sterile swabs called culturettes are good for this type of sampling. The cul — turette is presterilized and comes with a fluid- filled glass ampoule to provide just the right amount of moisture. The ampoule and swab are housed in a sterile plastic tube. About one minute before collecting the sample, squeeze the area of the tube over the ampoule to break the ampoule and release the fluid, which then soaks the cotton swab. Slide the moistened swab from its sterile tube and use it to wipe one square inch of the area to be tested. Then insert the swab back into the sterile plastic tube for shipment to the lab. Since this method uses liquid, the fungal spores will be hydrated and begin to colonize. It is important to ship the specimen to the lab via overnight delivery service or the test may be invalid.
Vacuum Dust Collection A filter designed to fit on a domestic vacuum cleaner is used. Since the filter’s pores are smaller than mold spores, any mold spores present are collected. The filter canister is then shipped to a laboratory for analysis.
Other Mold Test Methods The practice of testing for molds by letting spores settle on an open culture dish is now discouraged by knowledgeable specialists. Since certain harmful molds such as Aspergillus and Penicillium are very light and have a tendency not to settle on culture dishes, they are underrepresented in the analysis. Other methods of testing for airborne fungal spores and contaminated materials are available but require a trained technician with sophisticated equipment.
Although radioactivity in building materials is rare, John Bantas home inspections have revealed radioactive stone and tile glazes. Highly radioactive materials can be tested simply by holding a radiation detector next to the material.
For lower levels ofradiation, measurements of longer duration should be performed. Place at least one pound of the material in question in a glass container with an instrument for measuring radioactivity. A useful instrument designed for this purpose is Radalert loo, whose small size allows it to fit easily inside a one-gallon glass pickle jar along with the material to be tested. Set the meter for total counts and leave it to measure for a timed period of 12 to 24 hours. As a control, the test must also be performed in the same way, in the same location, but with the jar empty. Repeat both tests several times to be sure a radiation-emitting solar flare or short-term cosmic event did not interfere with the results. To obtain an average count per minute, divide the total number of counts recorded for each test by the total number of minutes the test ran. A substance that measures less than 10 percent higher than the control test is considered to be free of radiation. Readings more than 20 percent higher than the control test are considered to be significant.
