MOLD 101
Mold is everywhere.  It’s in every breath you take and in every breath you will take for the rest of your life.  Mold is in every house you have ever lived in or will live in.  There will always be mold spores floating around your home.  How did they get there?  You brought them in, on your shoes, your clothes, your hair, your food. They blew in on that delightful fresh breeze through your open window.
When should you be alarmed about mold in your house?

• If it is present at extremely high levels.
•  If you or the members of your household are ultra sensitive or hyper allergic to it.
•  If it is a species of dangerous mold.

Dangerous mold.  There are a couple of dangerous molds, but they are surprisingly rare.  I have only come across one verified instance in my real estate career.  I am talking about the dreaded stachybotrys, or misleading “black mold.”  I say misleading because most species of mold are black.
Where does dangerous mold grow?  A warm place where there is a continuous supply of moisture, a dripping pipe inside a wall, or a low spot under a house where water accumulates and stays there all year round, the attic where an unconnected bathroom exhaust pumps hot, wet air every day.
When should you have a test performed to determine the mold levels in your house?

• Test when an expert tells you to test.  I am not an expert.
• Test when you see or smell suspicious black stuff.

Who do you call?  You call a professional environmental testing company, and my preference is to call one that does NOT bid on the remediation of their own findings, and which does not recommend a remediation crew.  No conflicts of interest.
What does the testing company do?  Their main tests compare two or more air samples.  They take an air sample from outdoors near the house to set a baseline for the immediate environment.  Then they take one or more air samples inside the house for comparison.  The outside sample and the inside sample(s) should be similar.  If “suspicious stuff” has been pointed out, they may also take a physical swab for identification.
Air samples and physical samples go back to a lab for analysis.  A rather lengthy report is generated that usually includes:

• descriptions and levels of the fungal species present
• the testing company’s recommendation for remediation protocols.

If remediation is recommended, the testing company will return (at additional cost) to re-test.
How much does the testing cost?  Here in northern California, the environmental testing company I use charges $200 for the visit plus $100 for each sample, of which there are a minimum of two.  If you want to add the basement, another $100.  The attic?  Another $100.  Two swabs?  $200 more dollars.
You will spend $400 for the simplest two-sample procedure that answers two questions:

• Is there too much mold in the air of my house compared to established norms?
• What kind of mold is it?

The testing procedure is surprisingly quick.  I can usually get the Sacramento-based inspector out within 48 hours, get a verbal report on the phone the next day, and the writing report from the lab on the following day.
OK, students.  There is going to be a test. Put away your blogs and websites.  Take out a piece of real paper and a pencil.  STOP!  DON’T CHEW ON THAT PENCIL!  DON’T YOU KNOW THERE’S MOLD ON THAT PENCIL?