What should I do if I suspect mold in my home?

This question about mold remediation comes up a lot. The first thing to remember is that you should investigate, not test. Here are some tips for at-home mold investigation:

• Look for visible mold growth. Mold often looks cottony, velvety, rough, or leathery. It may have different colors (white, gray, brown, black, yellow or green). Mold may appear as a staining or a fuzzy growth on furniture or building materials (walls, ceilings, or anything made of wood or paper). Also look for signs of moisture or water damage (i.e., water leaks, standing water, water stains, condensation, etc.) as these could indicate a mold problem.
• Check around air handling units (air conditioners, furnaces, etc.) for standing water. Routinely inspect the evaporator coils, liner surfaces, drain pans, and drain lines. 
• Search areas where you notice mold odors. If you can smell an earthy or musty odor, you may have a mold problem.
• If people with an allergy to mold report some of the symptoms listed above, you may have a mold problem.