The unique scent of aged paper and bindings is known as “bibliosmia.” While this aroma is a source of pleasure for many readers, it raises questions about the safety of handling older materials. Potential hazards relate to both the chemical compounds released by the paper and the biological matter that accumulates over time. Assessing the overall safety of your personal library requires understanding the source of the smell and the substances books collect.
The Chemical Recipe: What Creates the Old Book Smell
The iconic scent of an antique volume results from the paper’s slow chemical degradation over decades. Paper is primarily composed of cellulose and lignin, which break down through a process called acid hydrolysis. Acids within the paper interact with organic compounds, causing them to decompose and release airborne molecules called Volatile Organic Compounds (VOCs).
The specific scent profile is a cocktail of these VOCs, with each compound contributing a distinct note. For instance, the degradation of lignin produces a faint, sweet vanilla-like smell, as lignin is closely related to vanillin. Other compounds include benzaldehyde, which imparts an almond scent, and toluene and ethyl benzene, which contribute to a generally sweet odor.
Various alcohols and aldehydes, such as hexanol and furfural, may introduce slightly floral or grassy undertones. This chemical signature acts as a non-destructive indicator of the book’s condition, allowing conservators to gauge the state of preservation. The changing ratio of these VOCs creates the unique, musty, and pleasant smell.
Assessing Toxicity: Are the VOCs Harmful
The VOCs released by aging paper are technically irritants, but their risk to human health depends entirely on their concentration. In old books, compounds like vanillin, benzaldehyde, and toluene are released at extremely low, ambient levels. Many of these chemicals are common food additives and flavorings, considered safe for human consumption at typical doses.
Studies conducted in libraries and archives have measured the concentrations of selected VOCs, including toluene and acetic acid, finding them well below established safety thresholds for indoor air quality. While high industrial exposure can cause headaches, dizziness, or respiratory irritation, the minute amounts emitted by a book are unlikely to cause severe chemical poisoning. However, individuals with heightened chemical sensitivities may still experience mild, acute symptoms, such as slight headaches or nasal irritation, especially in poorly ventilated rooms containing many old books.
Beyond Chemistry: Non-Chemical Health Hazards
While chemical emissions are generally low-risk, the most significant hazards associated with old books are biological and physical. Books stored in damp or humid conditions often host mold and mildew, posing a more immediate threat. Mold spores, such as Aspergillus and Penicillium species, are easily inhaled when a book is opened, triggering allergic reactions and respiratory problems.
Exposure to these airborne spores can lead to symptoms like a runny nose, coughing, and eye irritation, and can significantly aggravate pre-existing conditions like asthma. In rare cases, inhaling certain fungal spores can lead to more serious fungal infections known as mycoses, particularly in individuals with compromised immune systems.
Old books also act as efficient collectors of particulate matter, including common house dust and dust mite fragments. The paper surface attracts and holds these particles, which are then aerosolized when the book is handled. This book dust is a potent physical allergen and a common asthma trigger, contributing to the “book allergy” experienced in older libraries or used bookstores.
Safe Handling and Preservation Practices
The risks associated with old books can be greatly reduced by implementing simple, actionable preservation and handling techniques. The most effective strategy is controlling the storage environment, as high humidity promotes mold growth and speeds up paper degradation. Books should be kept in a stable environment with a temperature between 60 and 70 degrees Fahrenheit and a relative humidity range of 30 to 55 percent.
Regular cleaning is also important to mitigate the accumulation of dust and biological matter. For routine maintenance, gently dust the outer covers and page edges using a soft, clean brush or a vacuum cleaner fitted with a soft-bristle hose attachment. If you encounter a visibly moldy book, ensure it is dry and handle it with caution, wearing protective gear such as an N95 mask and disposable gloves. For valuable or severely affected books, consulting a professional conservator is the safest method for mold remediation.