Mold is a type of fungus that exists everywhere, spreading through microscopic spores that float in the air. Paper and paper-based materials, such as books and documents, contain cellulose, an organic polymer that molds readily consume as a food source. This cellulose acts as a perfect nutrient base for mold spores when combined with moisture. Finding mold growth on these items is a common problem, especially when stored in less-than-ideal conditions.
The Health Risks of Airborne Mold Spores
The primary danger from mold on paper comes from the inhalation of its airborne spores. When mold colonies are disturbed, they release a concentrated burst of these spores into the surrounding air. These microscopic particles can trigger a range of allergic reactions in sensitive individuals, which is the most frequent health effect of mold exposure. Symptoms often resemble hay fever, including a stuffy nose, persistent coughing, wheezing, and irritation of the eyes and throat.
Individuals with pre-existing respiratory conditions, such as asthma, are particularly vulnerable, as spore inhalation can provoke severe asthma attacks. Although less common, certain mold species that thrive on cellulose, like Stachybotrys or some Aspergillus species, can produce toxic compounds known as mycotoxins. People with compromised immune systems face a higher risk of developing more serious conditions, such as a fungal infection in the lungs. The level of risk depends heavily on the individual’s sensitivity and the duration and concentration of exposure.
Visual Identification and Environmental Triggers
Mold on paper is often first identified by a distinct, earthy, or musty odor, indicating active fungal growth. Visually, the mold can present in various textures and colors, which do not necessarily correlate with its danger level. Active mold growth may appear fuzzy or slimy, while dormant mold often looks powdery and dry. Colors can range widely, showing up as black, white, green, pink, or reddish-brown spots on the paper surface. A crucial sign of fungal activity is a change in the paper’s texture, as the mold secretes enzymes that break down the cellulose, leading to discoloration and brittleness.
Mold growth is directly tied to the environmental conditions surrounding the paper materials. The most significant trigger is high relative humidity, specifically levels sustained above 60 percent, which allows the dormant spores to germinate. Lack of air circulation is also a major contributing factor, as stagnant air allows moisture to condense on surfaces. Temperature is a factor, with optimal growth often occurring between 70 and 90 degrees Fahrenheit.
Practical Steps for Safe Removal and Preservation
Addressing mold on paper requires a methodical approach that prioritizes safety and prevents further contamination.
Safe Handling and Deactivation
Before handling any affected materials, don personal protective equipment, including an N95 respirator mask and disposable gloves, to avoid inhaling spores and direct skin contact. The affected item should be isolated immediately by placing it in a sealed plastic bag and moving it to a dry, well-ventilated location. To deactivate active mold, which is visibly wet or smearing, the paper’s moisture content must be reduced. This can be achieved by lowering the relative humidity in the isolation area to below 60 percent, or for highly valuable items, by freezing them to halt the growth.
Physical Removal
Once the mold is dry and dormant, physical removal can begin using a soft-bristled brush to gently sweep the surface, moving from the center of the page outward. The loose spores should be collected using a vacuum cleaner equipped with a High-Efficiency Particulate Air (HEPA) filter, which traps the microscopic particles instead of recirculating them. Liquid cleaners, including bleach, should not be applied directly to paper, as they can cause irreparable staining and structural damage. For documents that are severely compromised, structurally weak, or of high historical value, professional archival conservators should be consulted for specialized restoration techniques.
Long-Term Preservation
Long-term preservation focuses on maintaining a stable, dry storage environment. Documents should be stored in acid-free folders or boxes and kept in areas with consistent temperature and low humidity, avoiding damp basements or attics. Using a dehumidifier and ensuring adequate airflow around storage containers are effective preventative measures to keep the relative humidity below the critical 60 percent threshold.