Indoor air pollution in museums: a review of prediction models and control strategies

The calculation of pollution mass balances is explained with reference to modelling indoor air quality in museums, and the implication of pollution deposition on building interior and museum objects is discussed. A short overview of the museum environments key pollutants and their effect on materials are given. Case studies, which compare buildings with and without air-filtration, old and new buildings, or buildings in urban and rural areas, suggest that pollution mainly infiltrates buildings via free air movement and that passive control measures maybe sufficient to exclude outdoor pollutants. What this means for the level of indoor generated pollutants is not clear. Other studies have shown benefits from the use of active air-filtration, especially in urban areas with high pollution levels. The use of dosimeters rather than concentration measurements is now in focus in conservation research. Different approaches to setting acceptable limits for air pollution are briefly discussed, including the establishment of ‘adverse effect levels’. Introduction In late 2005 a comprehensive report was published on the condition and preservation needs of cultural heritage collections in the United States [1]. From a survey representing more than 30,000 institutions it was concluded that the most urgent need of US institutions is environmental control, and it was found that 47% of the responding institutions have had ‘some’ or ‘significant’ damage to their collections due to air pollution. However, air pollution is not a new museum phenomenon. In 1850 Eastlake, Faraday and Russell described the effect of air pollution on oil paintings in the National Gallery, London [2]. The special problems from indoor generated pollutants, e.g. emission from wooden storage or display materials, was noticed first by Byne in 1899 as he described corrosion damage to sea shells, however, Byne failed to link the damage and the poor storage conditions [3]. However, this was done a few decades later by Scott [4], and Nicholls [5], who described in detail the deterioration of lead medals housed in oak cabinets, and Mollusc shells in oak drawers, respectively [se also 6]. More recently, chapters on air pollution in Thomson’s book “The Museum Environment” [7], and texts such as the 1982 paper “Trouble in store” by Padfield et al [8] increased the attention to air pollution problems among conservators. One of the most cited articles on air pollution and museums is the 1990 review by Brimblecombe [9]. In his conclusion Brimblecombe listed the following issues as directions for future work (extract):