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| Education: Ozone: Effects on Materials in Libraries, Museums and Institutions |
| Wednesday, October 22, 2008 Posted by MarkCermak |
  In the aftermath of Hurricane Katrina, the devastation to structure, property and life has been documented as one of the worst natural disasters in U.S. history. As the Gulf coast regions begin to rebuild, the amount of water damage and mold that are being addressed by the professional restoration industry is overwhelming. There are many challenges facing the remediation professional that include mold remediation in schools, hospitals, high rise buildings and cultural institutions such as libraries and museums. There are many questions being asked in regards to finding alternatives to traditional mold remediation procedures, particularly with regards to using ozone as a biocide.
There is past and current research on the effects of ozone on natural or organic materials such as cellulose materials. Research from 1970 - 1980 on ozone also examines its effects on the atmosphere and the creation and use of ozone indoors and on the occupants. The effects of ozone are of particular interest for dealing with soot, fire or mold damaged cellulose materials that include all paper formats, textiles, art on canvas and paper, wood and photographs. The effects of ozone on film-based materials such as microfilm, motion picture film, and magnetic tape were also examined.
Background, Uses and Effects
Ozone naturally present in the atmosphere is very stable and is usually in concentrations of .03 ppm. It is often found in the air after thunderstorms and is generated by the interaction of sunlight with nitrogen dioxide from automobile exhaust. It screens out ultraviolet light and absorbs some harmful radiation. It primarily exists as a gas and has a pungent odor. It is affected by temperature, sunlight, pH, and organic matter. Ozone has been used as a drinking water disinfectant since 1893 and is still used in a variety of applications such as wastewater treatment, preparation of high purity water for the pharmaceutical industry and treatment of cooling tower water. Artificial ozone is created by passing an electric charge through oxygen and is highly reactive and very unstable. Artificially generated ozone is often released in concentrations greater than 1 ppm which is toxic to humans and animals. OSHA regulates exposure to 0.1 ppm: exposure in short duration is permitted up to 0.3 ppm. Artificial ozone seeks out unsaturated organic compounds such as soot, mold and molecules that create odors, and bonds with them neutralizing the smell. That means that the ozone changes molecular bonds and creates a new compound. Many of these new compounds act as bleaches and are very caustic. When natural or organic materials are exposed to ozone, the inherent chemical reactions already going on inside the item will begin to accelerate. Even with minimal exposure, ozone ultimately destroys organic, natural cellulose materials.
Some scientists use ozone’s powerful oxidizing properties to sterilize water and purify air. It can also be sued to sterilize food but the concentration needed may be irritating and toxic to humans. Many disaster recovery firms and cleaning companies generate ozone to be used in deodorizing contents and building materials affected by fire and smoke damage. While an effective deodorizer, the new compounds created by the reaction of ozone with other elements often times creates new chemicals that are sometimes caustic. If using ozone as a deodorizer on buildings, do not use in the presence of the building occupants. Ensure that the ozone is evacuated completely from the affected areas before allowing the building occupants to re-enter the space.
The increased use of ozone to treat microbially contaminated buildings have also been on the rise. Ozone is considered a gas-phase biocide and there are several limitations associated with its use. The ability to maintain an effective concentration, full contact and dwell time cannot be achieved as well as it’s toxic affects on the occupants of the building.
Using ozone in institutions that maintain documents or paper/cellulose items can be particularly devastating. Libraries, archives, museums and historical societies are full of cellulose, natural and organic materials, and particularly paper-based items. Most paper created between 1860 and 1980 is acidic. Chemical reactions occur constantly causing the paper to deteriorate, lose strength and become very brittle. When ozone is generated for use in deodorizing the cellulose and paper based materials, it tends to bond with the reactive chemicals already present and accelerate the aging process. Even a minimum amount of exposure to ozone will cause these materials to become more acidic. Ozone should not be used on any items of lasting value found in cultural institutions.
Ozone speeds up the invisible and damaging reactions in paper, creating more sulfur dioxide and hydrogen peroxide, and accelerating g acidic process. Ozone will cause paper to turn brown and become brittle. Eventually, the paper will become so brittle, that it will flake to the touch. Preservation and conservation activities in cultural institutions are designed to delay and retard deterioration of cellulose and film-based materials. Using ozone to eliminate mold and soot odors will destroy all advances in preservation efforts. Ozone should not be used with cellulose materials as it causes them to become brittle and decompose. Paintings, textiles, paper, film, furniture and leather are all organic materials and ozone is extremely damaging to these items.
When ozone comes in contact with photographs and film, it is even more destructive. Ozone increases the rate of oxidation of silver, destroying the images on film-based materials. It reacts even more quickly with color film than black and white. In strong concentrations, ozone can cause the images to flake off of the film. The chemicals that once interacted to create and stabilize the photographic images bond with ozone to cause the photograph to continue to develop. The same reactions occur when microfilm and motion picture film are exposed too ozone. In addition, ozone will react with the materials that make up magnetic media especially film-based materials.
Compact discs and laser or optical discs are also adversely affected by ozone. Ozone can bond with elements to create solvents that cause the protective polycarbonate layer to deteriorate, ultimately destroying the signal or data encoded on the discs.
Major concerns that need to be considered before using ozone are that there is no way to know all of the chemicals and molecules that are present in an environment that ozone can bond with. There is also no way to determine what ozone will create when it bonds with all of these molecules. Some of these molecules and compounds may be harmless and dissipate into the atmosphere but some of the compounds and molecules may be toxic and carcinogenic. There is no way to predict the behavior of ozone and air flow, temperature and potential elements to bond with must be factored into the high reactivity and unpredictability of ozone.
While an effective deodorizer and a purifier of drinking water, the long-term affects must be considered prior to using ozone in buildings. There are many environmental factors that also have an affect on ozone and how it reacts within the indoor environment. Just as many biocides have a place in restoration / remediation of indoor environments, the limitations and safety and health issues must be considered prior to its use.
References
MBK Consulting: Ozone: Effects on Materials in Cultural Institutions & Uses in Disaster recovery. Columbus, OH: MBK Consulting, 1994
The Northeast Document Conservation Center: Protecting Books and Paper Against Mold. NEDC, Andover, MA, September 1997.
The Library of Congress: A National Preservation Program Publication, Preservation Leaflet No. 2, ISSN 0160-9297, October 1983
Environmental Protection Agency: Mold Remediation in Schools and Commercial Buildings. EPA 402-K-01-001, March 2001
American Conference of Governmental Industrial Hygienists: Bioaerosols Assessment and Control. Cincinnati, Ohio: American Conference of Governmental Industrial Hygienists, 1999.
American Industrial Hygiene Association: Field Guide for the Determination of Biological Contaminants in Environmental Samples. Fairfax, Virginia: American Industrial Hygiene Association, 1996.
Eastern New York Occupational and Environmental Health Center: Bioaerosols, Fungi and Mycotoxins: Health Effects, Assessment, Prevention and Control. Albany, New York: Eastern New York Occupational and Environmental Health Center, 1999.
New York City Department of Health: The New York City Guidelines, Guidelines on Assessment and Remediation of Fungi in Indoor Environments. New York, New York: New York City Department of Health, 2000.
The Institute of Inspection, Cleaning and Restoration Certification: S500 IICRC Water Damage Standards. Vancouver, Washington: The Institute of Inspection, Cleaning and Restoration Certification, 2000.
Rachel Adams serves on the Board of Directors for the LMCCA as the Director of Health and Safety. Rachel is President of Indoor Environmental Management, Inc. located in Indianapolis, Indiana which is a full service consulting firm providing inspections of commercial and residential properties for indoor air quality issues. She has been an approved instructor for IICRC since 2003 and conducts training worldwide. She can be reached at 317-339-1291 or email rlaiam@aol.com.
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