Preservation of Historical Records (1986) / Chapter Skim
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3. Environmental Criteria
3. Environmental Criteria
Pages 11-32
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From page 11... ...
Because these documents, or at least their inforn~ation content, must be retained indefinitely, even very slow rates of deterioration caused by air pollutants could lead to unacceptable levels of accumulated damage over a period of several hundred years. The problem of protecting the National Archives inventory is thus quite different from the question of protecting common consumer products from premature deterioration over their short service lifetime.
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From page 12... ...
. A variety of additional air pollutants are recognized for which outdoor air quality standards have not been set at a national level.
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From page 13... ...
Acid mists and soot particles are often concentrated in particle sizes less than 1 ,um in diameter that are relatively difficult to remove when compared to coarser particles several micrometers in diameter. Unless a more sophisticated definition of particulate air quality is adopted than one based solely on total aerosol mass concentration, there is a danger that ventilation systems will be designed that will lower mass loadings without achieving a proportionate reduction in damage potential.
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From page 14... ...
PRESERVATION OF HISTORICAL RECORDS :~4': Historical records requiring immediate preservation to avoid loss of information. Damage can result from deterioration of the paper, ink, and binding as well as from handling.
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From page 15... ...
Sulfur dioxide is readily absorbed by uncoated wallpaper, but the absorption process can be retarded by vinyl coatings on the paper surface ;Spedding andRowlands, 1970; Walsh et al., 1977J. Once absorbed by the paper, SO2 can be oxidized, thereby contributing to the acidity of the paper.
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From page 16... ...
Chemical analysis showed that the deposits contained carbonaceous material, with 21 percent to 30 percent of the carbon present as black elemental carbon, which is the ratio of elemental carbon to total carbon close to that observed in atmospheric aerosol samples in downtown Los Angeles [sass et al., 1984~. This study, plus experience with particle samples filtered from the atmosphere onto paper substrates, suggests that both coarse and fine particles must be controlled if these colored atmospheric materials {i.e., elemental carbon and soil dust types)
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From page 17... ...
ENVIRONMENTAL CRITERIA 1 Bound volumesin storage stacks at the NationaJArchives. Leatherand cloth, as wed as paper, pigments, andinks, are affected by environmental conditions.
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From page 18... ...
Corrosion of Metals In common experience, paper clips, staples, and other metal fasteners corrode and stain paper-based documents stored in poorly controlled environments. However, such effects have seldom been observed in documents stored under good environmental conditions at the National Archives, and virtually none for the post-1940 records.
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From page 19... ...
Sulfur Dioxide Levels In the absence of deliberate pollutant removal, the indoor level of the pollutants generated outdoors might be expected to approach the level in the outdoor air that feeds building ventilation systems. Thomson {1965)
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From page 20... ...
Peak 1-hour average ozone levels inside one such museum in Los Angeles have been observed at 143 ppb compared with 173 ppb outside, or 83 percent of the outdoor level. This is consistent with observed values in the gallery at the Sainsbury Center for Visual Arts in England, where indoor O3 levels of up to 40 ppb were observed inside a modern art gallery in the presence of peak outdoor levels of 58 ppb, or 69 percent of the outdoor level {Davies et al., 1984~.
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From page 21... ...
In the Madison Building of the Library of Congress, a packed bed of Purafil for acid gas removal reduced the indoor NOX levels to the range of 4 to 154 ppb in the presence of outdoor levels of 46 to 318 ppb. These data show that the wash and Purafil systems are much less effective for NOX removal than for SO2 removal, but the reason is not yet clear, since laboratory tests show Purafil to be effective.
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From page 22... ...
Particulate Matter Removal Even though most forced ventilation systems contain some form of particle filtration device, very little literature exists on the detailed effect of these filters on the chemical and soiling aspects of air quality in archives, libraries, and museums. Particulate matter concentrations were not measured during the recent examination of the National Archives Building, the National Gallery, and the Library of Congress {Mathey et al., 1983~.
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From page 23... ...
Both aerosol mass concentration and the soiling index were monitored during the study, and a greater attenuation of the aerosol mass concentration than of the soiling index between outdoors and indoors was found. That observation is consistent with the hypothesis that soot particles contributing to the soiling index values are primarily concentrated in the fine particle sizes that may negotiate building air inlets more readily than coarse particle material.
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From page 24... ...
Total aerosol carbon particle levels inside were almost identical to total aerosol carbon levels outside, but black elemental carbon levels indoors were lower than those outdoors, suggesting an indoor source of aerosol organic carbon. This poor filtration efficiency for fine particles should be avoided in future designs, since the fine particle fraction of the outdoor aerosol burden contains much of the black soot and acidic material.
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From page 25... ...
Tables 3-3 and 3-4 summarize the variety of recommendations that have been made. Evidence that good environmental control will make a significant difference to the future of the National Archives is provided by a direct inspection of the present Archives collection by members of the committee who are experts on the condition of the Library of Congress collection.
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From page 26... ...
This evidence, plus the realization that the vast majority of the Archives collection will remain on paper for the foreseeable future, argues in favor of the committee's endorsement of both the draft ANSI standard, Practice for Storage of Paper-Based Library and Archival Materials, and the suggested NBS standards for proposed environmental control in archives. Where the two sets of recommendations are in conflict, the more restrictive requirement is endorsed {e.g., the proposed ANSI recommendations for O3 and particulate matter)
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From page 27... ...
Much of the intended environmental protection apparently can be provided by passive control (e.g., the laoxes) rather than by complete reliance on expensive active control measures {e.g., air conditioning)
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From page 28... ...
It will be noted that the minimum detection limits listed for O3 and SO2 are slightly higher than the proposed ANSI standards. These detection limits appear to be close enough to the stated objectives that a rational approach might well be first to design the building air conditioning system to meet the air quality objectives and then to monitor for equipment failure by determining whether pollutant levels exceed instrumental detection levels similar to those given in Table 3-6.
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From page 29... ...
The continuous-monitoring approach probably would require having a skilled air monitoring technician on the National Archives staff to maintain the equipment. Alternatively, the monitoring equipment might be maintained by arrangement with other local government agencies that currently operate continuous ambient monitoring systems for outdoor air quality.
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From page 30... ...
Measurement of the Concentration of Sulphur Dioxide, Nitrogen Oxides, and Ozone in the National Archives Building.
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From page 31... ...
1971. Reactions of fabrics made from synthetic fibers to air contaminated with nitrogen dioxide, ozone or sulfur dioxide.
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From page 32... ...
Record storage stacks showing odder style of government filing system that required documents to be folded. The NationaJArchives is currently refiling these records in covered box storage.
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