Listen to The Mould Show Podcast on ITunes

The Silent Scourge: The Unseen Mould Threat to Your Treasured Collections

Uncategorized Nov 26, 2023

Imagine this: your cherished collection of books, personal documents, legal papers, or even prized vinyl records, fine art prints, and photographs—items that carry irreplaceable personal value and history—fall victim to an invisible assailant. Without a sound, without a warning, they could be deteriorating, page by page, memory by memory. This is not a hypothetical situation exclusive to the dusty shelves of old libraries; it's a reality that could affect anyone's collection. Through the lens of extensive research into mould in libraries, we can gain insights into this silent menace and learn how to protect our own treasures from its grasp.

Introduction to Mould Threats in Libraries

Libraries are treasure troves of knowledge, but they face various threats that can damage their precious collections and the buildings they reside in. While fires have historically been a major concern, often triggered by warfare, sabotage, or negligence, there's a silent destroyer that's been overlooked: mould.

mould and its microbial companions, like mildews, are insidious. They don't just mar the pages or bindings of books; they introduce a musty scent that's often the first sign of their presence. The problem is compounded by climate change, with its extreme weather patterns leading to water damage that creates a breeding ground for these organisms.

Books and other library materials are particularly vulnerable to mould. These fungi are not just a menace to the items but also pose a significant health risk to library staff and visitors. Known to trigger respiratory problems, allergies, and even the debated "sick building syndrome," moulds are a hidden hazard, especially for librarians and archivists who work closely with affected materials.

While the health implications are notable, this paper zeros in on the fungi responsible for the biodeterioration of library assets, uncovering a threat that could undermine the very fabric of our repositories of history and culture.

Understanding Air Sampling in Library Environments

In the fight against mould in libraries, air sampling plays a pivotal role in understanding and assessing the extent of microbial threats. The choice of air sampling methods hinges on several factors including the specific indoor conditions of the library, the goals of the research, and the levels of microbial presence.

Active air sampling techniques are widely used, which employ a pump to draw air over a collection medium at a consistent rate. Culture-based air sampling is a go-to approach in this realm. It works by capturing airborne particles on an agar plate, which then allows for the growth and quantification of mould spores, presented as colony-forming units (CFUs) per air volume.

There is a variety of air sampling methods at our disposal, from traditional culture techniques to advanced DNA and chemical analyses. These methods can collect samples from various sources like the air, dust, surfaces, and even directly from visible fungal growth. Among the specialized tools are impaction devices like the Andersen sampler, which segregates particles by size, and impingement methods that capture microbes in liquid, particularly useful in highly contaminated scenarios.

Meanwhile, filtration devices offer a simpler and more cost-effective solution, trapping airborne microorganisms on membrane filters. Non-culture methods, like spore traps, provide a quick estimate of total airborne particulates but fall short in distinguishing specific fungal types, especially when the spores lack distinctive features.

For those elusive fungi with generic spore structures, culture-based techniques are still the most effective means of identification. These diverse sampling methods, each with their own strengths, give us the arsenal we need to detect and quantify the mould lurking in our libraries.

Surveying Microbial Presence Through Surface Sampling

Surface sampling is a key detective tool in the library mould investigation, helping us to identify and understand the colonies of microorganisms that dwell on surfaces. There are three primary methods each tailored to different scenarios.

Swab sampling is akin to an archaeological dig. A sterile swab is used to collect a sample from the surface, particularly effective for those hard-to-reach nooks and crannies or textured materials. The swab picks up a microbial community which is then suspended and analyzed.

Then there's the contact plate method, also known as a RODACplate. This technique involves rolling a plate with a growth medium over the area of interest. The collected microbes then grow into colonies, providing a clear picture of who's been living on the surfaces.

Lastly, we have the adhesive tape technique. It's the non-invasive member of the trio, gently lifting fungal particles from the surface onto a piece of tape. While it can't tell us if the spores are ready to grow, it can reveal the identity of some species and doesn't require any fancy equipment.

Each method offers a window into the microbial ecosystem of a library, showing us not just the organisms present but also how they interact with their environment.

Fungal Contamination in Libraries: A Comprehensive Literature Review and Findings

A thorough literature review was conducted to understand the scope of fungal contamination in library settings, searching databases with terms like 'mould in libraries' and 'biodeterioration of books.' This review encompassed studies irrespective of their sample type, methodologies, or geographic locations and grouped them based on the sampling strategy used: surface and dust, air, or a combination of methods. The three primary fungal genera identified were noted, but studies that did not specify fungi types were omitted.

The outcome of this review includes an analysis of 53 studies that pinpoint fungi at the genus or species level within libraries. These studies employed various sampling methods, including air samples, surface swabs, and vacuum samples. Initially, moulds were primarily identified through their microscopic and morphological features. However, a shift towards molecular techniques, especially PCR targeting the ITS region, has been noted in more contemporary research.

Across different countries, the most prevalent fungi detected in library air samples were Aspergillus, Cladosporium, and Penicillium. These genera also dominated the findings in dust and on book surfaces, with Aspergillus frequently emerging as the most detected genus. In combined sample studies, Aspergillus was again at the forefront, appearing in over half of the cases.

Molecular methods have refined the identification process, with Aspergillus niger emerging as the most common species, found across six nations. Other frequently identified species included various types of Cladosporium and Penicillium chrysogenum. Notably, a human pathogenic fungus, Cryptococcus, was isolated from a library in Brazil, signaling a potential health concern.

This review underscores the pervasive presence of mould in library environments and the necessity for meticulous identification methods to protect both cultural heritage materials and public health.

Navigating Mould Contamination in Libraries: A Synthesis of Challenges, Findings, and Steps Forward

The challenge of assessing mould contamination in libraries is multifaceted, as highlighted in the discussion of various methods and difficulties in the field. The consensus is that multiple sampling techniques are essential for a comprehensive assessment, given that no single method provides a complete picture. Interestingly, despite varying protocols, studies globally report the same major fungal culprits: Aspergillus, Cladosporium, and Penicillium.

The focus of research has largely been on identifying these culturable fungi, with less attention given to remediation strategies or the health implications of exposure to indoor fungi—a topic that continues to stir debate due to the absence of universally accepted exposure guidelines. To address this, organizations like NIOSH and the ISO have begun to standardize monitoring techniques, with the ISO 16000 series leading the way in setting guidelines for indoor air quality.

Drawing conclusions, the pervasive nature of mould in libraries is a universal concern that transcends geographic boundaries. Various sampling methods—swabs, tape lifts, air sampling—are employed to detect and analyze these common moulds. The identification of Cryptococcus in a Brazilian library underscores the potential health hazards. Despite the lack of established safe levels of mould, remediation is widely advocated to mitigate both health risks and material damage.

Ultimately, the authors seek to guide scientific support for librarians and to elevate awareness of the destructive impact of mould on cultural heritage, which often receives less attention than more dramatic threats like fire damage.

In the face of this quiet destroyer, taking action is paramount. Whether you're a librarian guarding a community's history, a collector preserving nostalgic memories, or anyone who values the longevity of paper-based materials—be proactive. "When in doubt, get it tested." This simple mantra could be the difference between preservation and loss. Employ the strategies and insights from library research to safeguard your collections. Don't let mould have the final word on your treasures.


El Jaddaoui, I.; Ghazal, H.; Bennett, J.W. Mold in Paradise: A Review of Fungi Found in Libraries.
J. Fungi 2023, 9, 1061.


50% Complete

Get Your FREE Housing Mould Hazard Check

In less than 5 minutes you'll know if you need to take action about your water damage or mould concerns.