Lately, our office has received a flurry of phone calls concerning mold in the home or office. After explaining the health risks, as well as the proper procedures involved in removing mold, invariably the response is: “But can’t I just spray it with bleach?

CHLORINE BLEACH, or laundry bleach, has long been considered an “accepted and answer-all” to mold cleanup. Well-intentioned recommendations of the EPA and other federal, state and local agencies are perpetuating that belief. The new mold and mildew household products on store shelves mostly contain diluted solutions of laundry bleach.

Bleach – When it IS effective

Bleach is an effective sanitizing product that kills mold on hard surfaces, like countertops, bath tubs and shower glass.  That’s because the mold is only on the surface. It cannot send down “roots” on these hard surfaces.

Chlorine Bleach Is Ineffective In Killing Mold For These Reasons:

ALL molds reproduce by making “spores.” Mold spores are microscopic and continuously move through indoor and outdoor air. They only become visible when individual spores group together in one area. When mold spores find moisture indoors on porous and wood-based materials , they set down roots and begin growing and digesting whatever they are growing on in order to survive. That’s why molds will gradually destroy whatever they are growing on.  Mold spores only need three conditions to grow:  (1) Warmth, (2) Moisture, and (3) Food.  This food is the organic matter found in porous and wood-based materials, such as paneling, tack strip, baseboards, wall studs, drywall, ceiling tiles, carpeting, fabric, and paper.

The objective to killing mold is to kill its “roots.” But consider this important point: Bleach is 99% water. And water is one of the main components necessary for the growth of mold. Mold has enzyme roots growing inside porous materials, but the ionic structure of bleach itself prevents chlorine from penetrating into these materials. The chlorine just stays on the outside surface.  However, the water content penetrates and actually feeds the mold. That’s why a few days later you’ll notice darker, more concentrated mold growing again on the bleached area.

Whatever potential mold “killing” power chlorine bleach might have is also diminished significantly as the bleach sits in warehouses, on grocery shelves or inside your home – 50% loss in strength in just the first 90 days inside a never-opened container!  Chlorine constantly escapes through the plastic walls of its containers.

Chlorine bleach accelerates the deterioration of materials and wears down the fibers of porous materials.

Chlorine bleach off-gasses for a period of time. Chlorine off-gassing can be harmful to humans and animals. It has been known to cause pulmonary embolisms in low-resistant and susceptible people.


The most effective method to get rid of visible mold is by removing the affected areas. That means you need to remove and replace any contaminated porous and wood-based materials, including paneling, tack strip, baseboards, drywall, ceiling tiles, carpeting, upholstered furniture, clothing, and paper.  Removing mold found on studs and floor joists involves HEPA vacuuming, sanding the affected areas, applying an antimicrobial, making sure the affected areas are completely dry, HEPA vacuuming again, then sealing them with products specifically designed for that purpose.

BE CAREFUL! Unfortunately, the time you are most likely to stir up spores and be exposed is the very time you are trying to clean up your mold problem. That’s when you need to be the most careful. If the area is small and well defined, clean up can be done by you, as long as you are free of any health symptoms or allergies, and as long as you take measures to protect yourself (and the rest of your home) during the cleaning process.  You need to set up a containment barrier to enclose the area you are working on.  You need to wear a proper respirator, wear gloves, and wear googles.  You need to make sure that you don’t contaminate the rest of your home when you remove the moldy materials.

If the mold problem is extensive, such as between the walls, under the floors, or covering large areas, you should leave cleanup to a professional company, with technicians properly trained in mold remediation. In the Gillette area, call DISASTER RECOVERY at 686-0078.

WORRIED about mold in your home or workplace? Contact us TODAY for an inspection and evaluation of your situation. BUT FIRST, you may want to go ahead and read the NEXT article: Waging the War: A DIY Guide to Mold Remediation