How to Safely and Effectively Clean Mold

“Most people underestimate the exposure risk, skip the protective gear, and clean the surface without ever addressing what caused the mold in the first place,” says Shanina Knighton, PhD, RN, an adjunct associate professor with the Frances Payne Bolton School of Nursing at Case Western Reserve University in Cleveland who researches infections and hygiene.

Why You Should Clean Mold in Your Home (and What Can Happen if You Don’t)

• Stuffy nose
• Coughing
• Wheezing
• Sore throat
• Burning eyes
• Skin rashes
• Allergic bronchopulmonary aspergillosis

Gear: What Equipment You’ll Need to Clean Mold

Cameron Figgins, a contractor and the owner of Absolute Maintenance & Consulting in Los Angeles, an IICRC-certified firm, recommends the following protective gear.

• Respirator At minimum, wear an N95 respirator. A respirator covers your mouth and nose, preventing the inhalation of mold.

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• Sealed-Lens Chemical Splash Goggles Mold spores can get into your eye around the peripheral openings of standard safety glasses. Sealed goggles create a complete barrier around the eye area.

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• Nitrile Gloves Nitrile is a synthetic rubber that can resist chemicals better than latex with a lower risk of skin allergies. Look for six-mil gloves (meaning they’re 6 millimeters thick) to protect your hands from mold exposure and cleaning solutions.

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• Disposable Coveralls Ensure they’re rated for particle protection, which blocks mold from moving through the fabric to your clothing or skin, to minimize contamination.

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• HEPA Vacuum A high-efficiency particulate air (HEPA) vacuum is fully sealed, versus a household vacuum with a HEPA filter that can leak particles back into the air. HEPA filters are required to capture particulates of 0.3 microns with 99.97 percent efficiency.

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   For comparison, mold spores range from 2 to 100 microns in diameter, so they are well within this capture range.

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• Cleaning Solutions Dr. Knighton recommends using a 3 percent concentration of hydrogen peroxide or an EPA-registered cleaner, meaning the EPA has verified its effectiveness against certain microorganisms when used as directed.

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   You can also use detergent and water to scrub mold off hard surfaces, then dry completely.

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   Experts don’t recommend using chemicals like chlorine bleach to kill organisms like mold, since it’s usually not possible to fully sterilize an area. Inactive mold can still cause allergic reactions in certain individuals, so it must be fully removed (not just killed).
• Containment Materials If you have a large contaminated area near vents or other openings, you may need to seal off the openings to prevent spores from spreading, using a single layer of polyethylene sheeting and duct tape.

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• Various Cleaning Tools Other helpful items include a stiff-bristle brush, disposable microfiber towels (which absorb more microorganisms than cotton), and trash bags to contain and seal contaminated materials.

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How to Clean Mold Step-by-Step

The steps for cleaning mold or replacing the contaminated material depend on where the mold is growing. Start by putting on protective gear and addressing the source of the moisture, such as fixing a leaky pipe. Address your mold issue as soon as possible, following these tips from Knighton.

Bathroom Mold

1. Air it out. If it’s a small, enclosed space, turn on the exhaust fan or open a window first.
2. Spray dry areas with water. This reduces spores from becoming airborne during scrubbing.
3. Apply mold cleaner. Let the cleaner sit for 10 to 15 minutes.
4. Scrub with a stiff-bristle brush. After your timer is up, wipe the area with a disposable cloth and dry the surface completely.
5. Remove and replace the caulk entirely, if needed. This is necessary if the mold has permeated the caulk, as cleaning the surface won’t help.

Mold Around Window Sills

1. Wipe down the surface to remove any moisture.
2. Apply mold cleaner. Let it sit for 10 minutes, then wipe with a disposable cloth and dry thoroughly.
3. Replace the material, if needed. If the wood underneath feels soft, is crumbling, or has signs of rot, replace it entirely.

Under Sinks and Cabinets

1. Eliminate the source of moisture. To prevent recurring mold, remove everything from the cabinet after repairing the leak and inspect items for mold. Throw away contaminated items to prevent your other things from becoming moldy.
2. Vacuum the surfaces. Use a HEPA vacuum to remove the mold spores.
3. Apply mold cleaner. Treat all affected surfaces, including the walls and cabinet floor, and run a fan or dehumidifier to completely dry surfaces.
4. Replace the material, if needed. If the wood or other materials are swollen, soft, or crumbling, they aren’t salvageable.

Porous Building Materials (Like Drywall or Carpet)

Mold can grow into the fibers of porous materials such as drywall, carpet, and insulation. Scrubbing the exterior can’t always reach the problem, so full replacement is usually necessary.

1. Cut drywall. Remove at least 12 inches beyond the visible mold border in every direction.
2. Remove carpet and padding. Soft flooring materials that have been saturated need to come out entirely.
3. Seal all contaminated material in heavy-duty plastic bags. Do so before you carry the mold through any other part of the home to avoid spreading mold.

When to Hire a Professional

• Covers more than 10 square feet: That’s a patch roughly 3 feet wide by 3 feet long.
• May have contaminated your HVAC system: Look for mold near your air conditioner’s intake and around vents.
• Is from contaminated water. This includes water from sewage leaks and floods.

8 Strategies to Prevent Mold Regrowth

Once you’ve removed mold, create an environment where it cannot regrow — namely, one without moisture. Carver recommends these strategies to prevent mold from coming back.

1. Use a hygrometer. This is an inexpensive tool you can buy at a hardware store to measure humidity levels in your home. It’s best to keep your home’s relative humidity between 30 and 50 percent.
2. Add a dehumidifier. If your home’s relative humidity is above 50 percent, you may need a dehumidifier to remove moisture from the air. Empty the dehumidifier often and follow the manufacturer’s instructions on how to clean the device.
3. Improve airflow in your home. This also helps control moisture levels. For instance, open your bathroom window during and after showering or open your kitchen window when boiling water or washing dishes to remove moist air. Run exhaust fans that vent outdoors regularly in your kitchen and bathrooms.
4. Space out furniture. Move chairs, couches, and other furniture away from walls so they aren’t touching. This helps to improve airflow.
5. Filter your air. Use an Asthma & Allergy Friendly Certified filter in your HVAC system, which must pass standards to limit allergen exposure.

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    Alternatively, choose a filter with a minimum efficiency reporting value (MERV) rating of 13 or greater. A higher MERV rating means the filter is better at trapping particles.

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    This helps trap spores from your entire home and improve airflow. You can also use a freestanding air purifier in spaces with poor air quality, but these only filter air in a limited area, based on the device’s capacity and the room size.

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6. Wipe your washer. If you have a front-loading washing machine, wipe down the door and seal after use. Leave the door open to dry out the interior. Front-load washers are especially prone to mold since the rubber gasket around the door traps water after wash cycles.

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    Don’t leave wet clothes lying around.
7. Fix leaky roofs and pipes as soon as possible. Doing so prevents moisture buildup that can lead to mold.
8. Routinely check mold-prone spaces. These include dark spaces without airflow (like closets), rain gutters (remove debris), exhaust fans (clean or replace any filters, remove debris from grille cover, and clean blades), and under sinks (look for signs of leaking).

The Takeaway

• Mold can cause flu- or allergy-like symptoms in healthy individuals, and more serious issues for those who have allergies, asthma, chronic lung disease, or a suppressed immune system.
• Use protective gear like a respirator, splash goggles, and nitrile gloves while cleaning mold to prevent health risks.
• To clean mold, address the source of moisture, clean and dry the area thoroughly, and replace any porous materials like drywall or carpet that can’t be thoroughly cleaned.
• Hire a professional if the mold growth covers more than 10 square feet, your HVAC system is contaminated with mold, or the mold was caused by sewage or other contaminated water.