The musty scent of aged paper is a complex mix of volatile organic compounds released as materials degrade. While exposure to old books presents no health threat for many people, they can cause illness, particularly for those with pre-existing sensitivities. The primary risks involve exposure to accumulated biological matter and, in some historical volumes, toxic chemical residues. These irritants can trigger allergic responses and respiratory issues.
Biological Hazards in Aged Materials
The most frequent source of health issues from aged books comes from biological matter that has accumulated or grown within the paper and cloth fibers over time. Dust, which settles on book surfaces and between pages, is not merely inert dirt; it is a complex allergen reservoir. This accumulated debris contains decomposed organic products, including bacteria, fungal spores, and fragments of dead insects. These components can all cause mild to severe allergic reactions.
Mold and mildew thrive on organic materials like paper and leather when relative humidity exceeds 65 percent, releasing microscopic spores into the air. Inhaling these spores can lead to respiratory problems such as allergic rhinitis, characterized by symptoms like sneezing, a runny nose, and itchy eyes. Furthermore, certain molds produce toxic by-products called mycotoxins. Exposure to high concentrations of spores can exacerbate conditions like asthma or trigger flu-like symptoms.
Dust mites also contribute to the biological hazard, feeding on shed skin cells and fungi in the dust. Allergies are caused by inhaling their minute waste particles and fragmented body parts, not the mites themselves. These airborne particles can cause hay-fever-like symptoms and wheezing, especially when a dusty book is opened. Continuous exposure to these low levels of airborne dust and mold can increase an individual’s sensitivity over prolonged periods.
Hidden Chemical Contaminants
Beyond biological hazards, certain older books contain chemical contaminants introduced during their manufacturing process. A notable example is the use of heavy metals, such as arsenic, lead, and chromium, which were historically incorporated into pigments and dyes to create vibrant colors. During the Victorian era, for instance, arsenic compounds were used to achieve bright green shades on cloth book covers.
Recent studies have shown that some 19th and early 20th-century volumes contain levels of heavy metals that exceed safety thresholds established by organizations like the Centers for Disease Control and Prevention. Researchers testing some of these cloth-bound books found lead and chromium concentrations significantly above acceptable limits for chronic exposure. Chronic exposure to these elements, often through inhalation of dust from the degrading cover materials, is associated with serious health issues including respiratory problems, lung damage, and even cancer.
Chemical concerns also stem from the degradation of the paper itself, particularly in books printed using high-acidity processes. As this paper ages, it breaks down, releasing acidic paper dust and volatile organic compounds (VOCs) into the air. Historically, some libraries used potent chemicals, such as fumigants like DDT, to control pests, leaving behind toxic residues that can off-gas. These chemical components represent a distinct toxicity risk separate from biological allergens.
Safe Handling and Storage Practices
Minimizing the health risks associated with old books centers on controlling the environment and implementing clean handling practices. The most effective way to prevent mold and mildew growth is to maintain a stable, relatively dry environment, ideally with a relative humidity between 40 and 50 percent. Storing books in basements or attics should be avoided, as these locations often experience the extreme temperature and humidity fluctuations that encourage biological growth.
When handling older volumes, especially those that are visibly dusty or moldy, wearing gloves and a high-efficiency particulate air (HEPA) mask is advised to prevent skin contact and spore inhalation. Cleaning should be performed regularly using a soft cloth or a vacuum cleaner equipped with a HEPA filter and a soft brush attachment to remove loose dust. Work outdoors or in a well-ventilated area when cleaning dusty books to allow airborne particulates to disperse.
After any handling session, thorough handwashing is a simple but effective measure to remove any residual dust or chemical contaminants that may have transferred from the book cover or pages. For books suspected of containing heavy metal dyes, sealing them in an archival-quality, non-acidic plastic enclosure can prevent the toxic compounds from shedding dust into the air. Proper care focuses on mitigating the transfer of both biological allergens and chemical residues from the book to the reader.