There are over 360,000 public libraries and 50,000 museums worldwide that house countless cultural and heritage artifacts and documents. All of these buildings must provide an environment that protects and preserves these materials – but many don’t. A survey report on indoor air quality management in European museums found that the majority of the institutions have not measured airborne pollutants and do not know the damages related to poor environmental quality conditions.
This general lack of awareness when it comes to the dangers of poor indoor environmental quality in museums and libraries is a cause for concern. Outdoor pollution and indoor pollution create an environment that is not only harmful for human health and safety but more importantly for museum and library collections. The materials are typically sensitive to factors such as humidity, temperature, light as well as concentrations of volatile organic compounds and particulate matter. They do not have inherent mechanisms to withstand the adverse effects of pollutants. Exposure can cause corrosion, tarnishing, fading, or embrittlement leading to irreversible decomposition and damage. It is important to understand which pollutants cause negative effects and how to manage and monitor them to ensure optimal environmental quality conditions.
Understanding environmental quality in museums and libraries
There are a number of factors that need to be considered when it comes to indoor environmental quality in public buildings such as museums and libraries. Aside from the effects on health and well-being that can range from allergies, headaches to respiratory and heart issues, there is the costly and considerable damage on cultural objects that museum and library directors should be aware of:
Temperature
- High temperature causes discoloration and disintegration of organic materials such as wood, paper, textile, leather or skin and softening of adhesives or lacquers. High temperatures also increase chemical reactions to materials such as films – which if left undetected may lead to a fire.
- Low temperature causes biological reactions and activities such as mold growth, insect and mite infestation
- Fluctuating temperatures can cause stress on materials with abrupt contraction and expansion
Relative Humidity
- Higher humidity levels cause warping and swelling of wood, fading of ink dyes as well as biological activities such as mold growth and breeding of insects
- Lower humidity levels may result to dessication of paper and fibers, shrinkage, flaking and cracking of wood, photographic emulsions, ivory and paper
Light
- Low light levels over prolonged periods can cause as much damage to cultural objects as high light levels for brief periods of time.
- Incorrect lighting levels can cause darkening, yellowing, fading, embrittlement and many other changes that can be irreversible.
Air pollution
- Particulate air pollutants such as dust, mold, fibers and pollen can act as catalysts for chemical reactions that form damage-causing acids such as acetic acid or sulfuric acid; they also attract moisture that cause problems such as molds and mildew
- Gaseous air pollutants emitted from outdoor and indoor sources such as sulfur dioxide and nitrogen dioxide from combustion and burning fossil fuels; ozone coming from equipment such as photocopying machines, printers or air filtering devices; formaldehyde from preserving fluids, woods, glues and adhesive materials; phthalates from plastics and cleaning materials and many others
Object Materials | Deterioration | Primary Air Pollutants | Environmental Factors Accelerating Damage |
metals | corrosion/tarnishing | sulfur oxides and other acidic gases | water, oxygen, salts |
stone | surface erosion, discoloration | sulfur oxides and other acidic gases, particulates | water, temperature fluctuations, salt, vibration, microorganisms, carbon dioxide |
paint | surface erosion, discoloration | sulfur oxides, hydrogen sulfide, ozone, particulates | water, sunlight, microorganisms |
textile dyes and pigments | fading, color change | nitrogen oxides, ozone | sunlight |
textiles | weakened fibers, soiling | sulfur oxides, nitrogen oxides, particulates | water, sunlight, mechanical wear |
paper | embrittlement | sulfur oxides | moisture, mechanical wear |
leather | weakening powdered surface | sulfur oxides | mechanical wear |
ceramics | damaged surface | acid gases | moisture |
Source: https://www.nps.gov/museum/publications/MHi/CHAPTER4.pdf
Continuous real-time indoor environmental quality monitoring as an active management strategy
Museum and library directors are faced with the difficult challenge of balancing the right environmental conditions for the health and well-being of employees and visitors, and the conservation of cultural materials. The environmental quality conditions for human health and comfort may be different from what is required to protect objects and papers. Moreover, different collections require different environmental conditions. Precise monitoring is therefore essential to understand the dynamics of the different air quality factors and how you can control them to achieve stable environment conditions.
- Determine the concentration levels of pollutants and promptly address the risks related to suboptimal conditions
- Assess and manage the right threshold levels for occupied and unoccupied spaces in the museum or library
- Identify patterns and trends of deterioration caused by poor indoor air quality and make thoughtful decisions to minimize and prevent irreversible damage
- Prevent costly and unnecessary repairs, restorations, as well as dangerous accidents such as fires and explosions
The data and actionable insights from real-time indoor air quality monitoring can provide museum and library directors with greater knowledge to preserve the precious collections and provide a healthy and safe facility for employees and visitors.
