Aspergillus is a widespread mold found naturally in both indoor and outdoor environments. When Aspergillus grows indoors, it can pose risks to human health and building integrity. Prompt remediation helps mitigate these potential issues.
Understanding Aspergillus and Its Presence
Aspergillus is a genus of mold with over 200 species, many of which thrive indoors. These fungi are aerobic and can grow in a wide temperature range, from 68 to over 100 degrees Fahrenheit, which is well within residential temperatures. They commonly grow on surfaces.
Moisture is a primary catalyst for Aspergillus growth indoors, often originating from elevated humidity or water damage. The mold also requires a food source, including common organic building materials like paper, fabric, wood, drywall, and dust. Within 48 hours of contact with water, active mold growth can begin, releasing microscopic airborne spores that spread throughout a structure.
Visual indications of Aspergillus can vary in color, appearing as black, blue-green, gray, or tan patches; some colonies might be flat, while others are more elevated and textured. Beyond visual cues, a distinctive musty odor, sometimes described as earthy or damp, often signals mold growth, even if not immediately visible. This smell is a key indicator, particularly when mold is hidden behind walls or under flooring.
Steps for Effective Remediation
Initiating small-scale Aspergillus remediation requires careful preparation to ensure safety and prevent spore dissemination. Personal protective equipment (PPE) is important, including gloves, eye protection, and a respirator mask rated for mold spores. Disposable laboratory coats can also help protect clothing from accidental contamination.
Containing the affected area is a subsequent step to prevent spores from spreading to unaffected parts of the home. This can involve sealing off the contaminated space with plastic sheeting and duct tape, and potentially installing negative air pressure barriers to keep spores within the work zone. Removing contents from the affected area, except for large salvageable furniture, is advisable to prevent cross-contamination.
For mold removal, porous materials like drywall or insulation with extensive mold growth need to be removed and replaced, as mold can penetrate deeply. For non-porous materials such as metals, glass, or hard plastic, and semi-porous materials like wood or concrete, surfaces should first be wet down lightly with a water-and-detergent solution to minimize airborne spores. A high-efficiency particulate air (HEPA) vacuum cleaner can also be used to remove surface mold and spores.
Thorough cleaning of surfaces follows removal. A non-ammonia soap or detergent with hot water, or a commercial mold cleaner, should be used to scrub all moldy surfaces. After scrubbing and rinsing with clean water, a disinfectant solution can be applied. For instance, a solution of one cup of household bleach (5-6% sodium hypochlorite) per gallon of water, or undiluted white vinegar (5-6% acetic acid), can be effective on non-porous surfaces. Hydrogen peroxide (3% solution) can also be sprayed directly onto surfaces and allowed to sit before wiping. Ensure adequate ventilation when using disinfectants, and never mix bleach with ammonia.
The final step involves ensuring the area is completely dry to prevent future growth. After cleaning and disinfecting, affected surfaces should be dried as quickly as possible, which can be accelerated by using fans and dehumidifiers. Moisture levels in materials like wood should be less than 12-15% before any rebuilding or painting occurs.
When to Seek Professional Help
While small mold problems can be addressed by a homeowner, professional Aspergillus remediation is recommended in specific situations. If the affected area of mold growth exceeds approximately 10 square feet (roughly a 3-foot by 3-foot patch), it is too large for a do-it-yourself approach. Large colonies can spread easily and require specialized containment and removal methods.
Mold growth resulting from contaminated water, such as sewage, necessitates professional intervention due to heightened health risks from potential pathogens. The presence of mold in heating, ventilation, and air conditioning (HVAC) systems also requires experts, as spores can circulate throughout the entire property, making widespread contamination likely. Professionals use specialized equipment like HEPA vacuums and air scrubbers to effectively remove mold spores and moisture from these systems.
If individuals in the household have compromised immune systems, severe allergies, or pre-existing respiratory conditions like asthma, professional remediation is advisable, even for smaller mold issues. These individuals are more susceptible to adverse health effects from mold exposure. If a musty odor persists despite cleaning, or if mold is suspected behind walls, under flooring, or in other hidden areas, professional assessment using tools like moisture meters and infrared cameras can pinpoint the problem. If previous DIY attempts to remove mold have failed and the mold has returned, it indicates a more deeply rooted issue that requires professional expertise to resolve the underlying moisture problem.
Preventing Future Growth
Preventing future Aspergillus growth centers on moisture control within the indoor environment. Promptly addressing any leaks from roofs, pipes, or windows is important, as water intrusion creates ideal conditions for mold proliferation. Thoroughly drying any wet areas within 24 to 48 hours after spills or floods is also important to inhibit mold growth.
Maintaining appropriate indoor humidity levels is another preventative measure. Experts recommend keeping indoor humidity between 30% and 60% relative humidity. Using dehumidifiers, especially in damp areas like basements, can help regulate moisture levels, and air conditioners can assist in controlling humidity.
Proper ventilation in high-moisture areas such as bathrooms, kitchens, and laundry rooms is beneficial. Using exhaust fans when showering or cooking helps remove excess moisture from the air, preventing its accumulation on surfaces. Regularly cleaning and maintaining HVAC systems, carpets, and furniture can reduce dust, which serves as a food source for Aspergillus. Ensuring proper drainage around a home’s foundation can prevent moisture from seeping into basements and crawl spaces.