dirt or is it mold

Is it Mold or is it Dirt?

Is it dirt or is it mold? Sometimes we can confuse dust or dirt as mold.

We get this question “dirt or is it mold” asked a lot.  Usually, it’s not that hard to distinguish between mold and dirt, but sometimes we are not absolutely certain either.  Distinguishing mold from dirt just by looking at a picture or looking from a distance can be really difficult, but there are some tell-tale signs.

We’ve listed some of the things we look for.  These are merely guidelines and not absolutes, and we are sure there’s an example that would contradict each of these statements.  But, by and large, these are good guidelines that might help you make a good guess.

Things to look for:

  • Mold likes to grow in areas of high humidity and little air flow. Consequently, an air conditioning duct wouldn’t normally be a place for mold because there’s lots of air flow and low relative humidity.
  • Mold needs something on which to grow. If you’re looking at something that’s steel or aluminum, it’s probably not mold.
  • Mold usually doesn’t wipe clean. It tends to grow into whatever it’s growing on.  If you dampen a cloth and can rub everything off, it probably isn’t mold.
  • Up close, mold has a velvet-like appearance. Also, it tends to vary in color intensity from bright to dull.
  • Mold will usually have an odor, especially when the room ventilation system is shut off. Most molds have a “musty” smell or a basement smell when there’s little or no air flow.  The odor is caused by the waste products of mold growth.  If possible, close off the room for a day and see if you detect any odor.
  • Mold doesn’t like lighted areas. If you’re looking at something that’s in a well-lighted area, chances are it isn’t mold.

Of course, the only definitive way to be sure is to sample it.  However, you can often save yourself some expense just by examining the tell-tale signs.


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