A professional mold inspector can be very helpful if conducted correctly, but an increasing awareness of the dangers of mold has likewise increased the number of so-called "professional mold testers" who don't understand the relationship between contaminants found in the air or dust and the sources from which they come. Adding to this issue, many mold test labs can incorrectly analyze the mold test samples, or write mold testing reports that are unintelligible to those who aren't scientifically trained for a mold test.
There are several ways a professional can do a mold test. Mold test options include bulk sampling (removing some contaminated material), air sampling (taking samples of air with various instruments to find bio aerosol, or airborne particulate matter arising from living things, such as mold), and surface sampling (the removal of dust with a vacuum device, sticky tape or a swab). These mold test samples are sent to a laboratory for a mold test analysis.
If you do decide to hire a professional mold inspector to do a mold test in your home, do your homework: request information about the person's mold training and education, ask how the sampling will be done, seek references, and find out what information will be included in the mold test report. By doing so, you can assure yourself that the mold test will be done correctly, the first time.
In the end, though, the most important thing to do is to figure out why the mold is growing, where the mold is, and to change the conditions so that, after you have the mold remedied, it will not return. Otherwise, the mold is bound to return, causing future headaches and costs. To remedy this, hire someone who understands buildings before you do a mold test, such as a home inspector who is trained in mold and a member of the American Society of Home Inspectors (ASHI).
To learn ways to prevent future mold problems, check out The Money Pit's tactful tips on mold prevention.