Dealing with Atmospheric Pollutants

Damage from air-borne pollutants is most evident in old books and in stacks of old papers, where the edges of pages are discolored from acid deterioration while the center portions remain almost white. Certain gases such as sulfur dioxide, hydrogen sulfide and nitrogen dioxide originate from burning fossil fuels and are most serious in industrial areas. As large and expensive filtering devices are necessary for removal, no economical means of protection is available for the small collector.

Some of the compounds are not dangerous until combined with other compounds to form acids; for example, sulfur dioxide is catalyzed by other airborne compounds to form sulfur trioxide, which unites with water vapor to form sulfuric acid. Ozone, a pungent gas generated by the interaction of sunlight and nitrogen dioxide from auto exhaust and one which is also prevalent around electric motors and after thunderstorms, causes the oxidation and consequent embrittlement of paper.

As dirt and dust carry absorbed pollutants which can be abrasive to books and paper, air in a storage room should be filtered, with frequent changes of filters in the system. Where filtration is not possible, objects can be stored in closed containers; if used, plastic bags should not be tightly sealed. Exhibit cases which are sealed against dust and dirt should provide air circulation through filters. As stagnant air increases the possibility of mold growth, any material stored in closed containers should be checked frequently. Also, the area should be cleaned and vacuumed regularly to eliminate dust and dirt buildup on any materials.