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How to Test for Black Mold

Do you keep getting a whiff of something musty in your bathroom or basement? Afraid it might be mold? Learn about three of the most popular kits to test for mold at home.

Black Mold iStock

It’s no secret that damp areas of the home provide the perfect conditions for mold and mildew to grow. Whether your nose knows, or your eyes spy dark spots in strategic locations, you want to make sure.

Mold doesn’t just eat away at your wood, wallpaper, or grout. Its spores get airborne and cause all kinds of health problems. The Centers for Disease Control and Prevention (CDC) says enough evidence exists to link mold to upper respiratory tract symptoms like itchy eyes and runny nose to cough and wheeze in otherwise healthy people.

What is black mold?

When people say “black mold,” they refer to Stachybotrys, a greenish-black mold that grows on damp material with a high cellulose content. In our homes, that includes wood, fiber or gypsum board, paper, fabric, or green insulation. Just because mold is black doesn’t mean it’s the dreaded Stachybotrys though, which by the way also manifests itself in blue and grey. But because Stachybotrys can off-gas dangerous mycotoxins, it’s the mold variety most feared.

Testing for mold in your home

If you hire a professional mold inspector to come to your home, they’ll take samples from three areas—the air, the surface, and surrounding dust. They send these samples to a third-party laboratory to find out the concentration and kinds of mold in those particular areas.

However, this procedure takes time and isn’t cheap. Fortunately, testing for mold in your home is a relatively easy task that can give you faster results and save you money. If you’ve done everything you can to prevent mold but still have reason to think the air you breathe is compromised with mold spores, check strategic locations for visible signs of mold.

Common areas of mold growth include:

  • Areas around plumbing lines, even behind the drywall
  • Below sinks
  • In the wall around leaking windows
  • In closets, particularly those storing leather goods
  • Under the carpet in damp areas or where there’s been a leak or flood
  • Behind the refrigerator
  • Coils of HVAC air handlers or ductwork
  • Between the furniture and exterior walls, particularly in basements or concrete block houses

How to test for black mold

If you find signs of or suspect mold in any of these areas, purchase a mold test kit. Mold test kits are available in most home improvement or hardware stores and from online retailers. But not all kits are the same. Read the labels to learn their differences. Options may include:

  • Kits that, within minutes, tell you mold is or isn’t present on a surface and what kind
  • Kits that tell you mold is in the air but don’t identify what kind
  • Kits that include lab fees in the purchase price, and others that don’t

Here are three of the most popular mold test kits, what they include, and how to use them.

Healthful Home 5-Minute Mold Test

This quick and easy test includes one test swab and one test strip for each Stachybotrys and Penicillium/Aspergillus that resemble those used in home pregnancy tests. It also includes three extra swabs if you decide to take more samplings for lab confirmation, a lab request card, and a pre-paid mailer.

To use this kit, simply swab the area, wet it in the solution in the syringe, and apply to the test strip. If you have one line, the test is negative. Two lines mean you have that type of mold present.

Mold Armor FG500 Do It Yourself Mold Test Kit

The Mold Armor kit includes a test swab, petri dish, and a bottle of mold growth medium. You can use this single kit in one of three ways—to test the air for mold spores, to test air quality in your HVAC duct, or to test for surface mold.

To use the kit, pour the growth medium in the petri dish, replace the lid, and allow it to gel for one hour. Then, either allow it to remain open to the atmosphere for an air quality test, tape it to your air duct for a HVAC test, or use the swab to remove a sample from a surface and apply it to the growth medium for a surface test.

If after 48-96 hours mold begins to grow in your dish, you may choose to send it to a lab for analysis. With a price tag of under $10, this mold test kit is affordable. But the lab fee is an additional $40.

DIY Mold Test

This easy test kit includes three tapes to lift samples from surfaces which you then mail back for analysis, a quick start guide, and a mold inspection booklet to walk you through the process. The $45 price of the kit includes the lab fees to test for all mold types, not just two or three. To use the kit, simply apply the tape to wherever you see mold in your home, lift off, and adhere to the enclosed sample card. You’ll receive an illustrated lab analysis report in the mail.

Before doing anything like cutting into drywall or removing baseboards to expose mold, don your personal protective equipment. The Environmental Protection Agency recommends when cleaning up mold (or possibly stirring up the spores) you wear long sleeves and pants, shoes, gloves, goggles without vent holes, and an N95 respirator.

If you receive positive test results, you can then decide if you want to remove the mold yourself or hire a professional.