Pollutant

== Description ==
An aerosol, or particulate contaminant. Pollutants are generated by natural and man-made sources, such as decomposition, abrasion, or combustion. Pollutants may be damaging or toxic to the environment, people, and materials. Currently the pollutants with the highest outdoor concentrations generally occur in big cities (nitrogen oxides, hydrocarbons, ozone, carbon monoxide, particulates) or near smoke stacks (sulfur dioxide, nitrogen oxides). Very dense haze, or combination of smoke and fog, is called smog. Indoor air pollutants (organic acids, aldehydes, hydrocarbons, ozone, particulates, etc) are emitted from construction materials (wood, insulation, carpets, paints), office machines (copiers, printers) or are transported inside from the outdoor environment. Once inside a museum, pollutants can deposit and interact deleteriously with museum materials. The concentration of air pollutants may be decreased by minimizing sources or by reacting or absorbing the pollutants from the air. Scavengers provide one method to minimize the concentration of air pollutants in contained spaces.
Comparison table of aerosol pollutants information from Canosa and Norrehed (2019) and Jean Tétreault (2011).
Pollutant 	Sources 	Collection Risks
Acetaldehyde; acetic acid 	Fuel combustion; wood (especially oak, cedar, etc.) and wood products, biological processes, PVC flooring, laminated materials, paints, adhesives, sealants, tobacco smoke, cellulose acetate decomposition; acetaldehyde is a precursor of acetic acid 	Metal corrosion, reaction with calcareous materials, cellulose and protein embrittlement, degradation of soda-rich glass, enamels, and pigments; acidification of paper
Formaldehyde; formic acid 	Fuel combustion, wood and wood products, resins, oil-based paints, natural history specimens, fiberglass, photocopiers, textiles, construction materials, PVC carpeting, laminates, tobacco smoke, gas ovens, adhesives, sealants; formaldehyde is a precursor of formic acid	Metal corrosion, reaction with calcareous materials, cellulose and, protein embrittlement, discoloration of dyes, pigments, and textiles; acidification of paper
Ammonia 	Latex paints, cleaning products, food preparation, HVAC systems, people, concrete, biomaterial degradation, fertilizers 	Crystal growth on cellulose nitrate objects, yellowing of linseed oil; corrosion of copper alloys
Ozone 	Smog, photocopiers, laser printers, electrostatic particle filters; UV light sources, arc welders 	Rubber, cellulose and protein embrittlement, dye, ink and pigment discoloration, photograph and book deterioration
Peroxides 	Secondary product from polymerization of alkyds, drying oil, urethanes, epoxies such as found in some adhesives and paints 	Cellulose degradation, black spotting on photographs, oxidation of proteins (leather and wool), discoloration or bleaching
Nitrogen oxides; nitric acid 	Biological processes, fuel combustion, cellulose nitrate decomposition, tobacco smoke, photocopiers 	Cellulose and protein embrittlement, dye, ink and pigment discoloration, photographic film deterioration
Sulfur dioxide; sulfuric acid	Fuel combustion, pulp and paper production, biological activity, pyrite oxidation, vulcanized rubber, proteinaceous materials inside enclosures 	Metal corrosion, dye fading, cellulose embrittlement, photograph deterioration, leather red-rot, pigment darkening, reaction with calcareous materials
Sulfides; hydrogen sulfide 	Fuel combustion, humans, natural gas, marshes, volcanoes, wool, silk, felt, furs, vulcanized rubber, waterlogged archaeological organic materials, pyrite collections 	Metal corrosion, photograph silver mirroring and redox spots, leather red-rot, lead pigment darkening, stone deterioration; paper and fabric discoloration
Particulates 	Combustion residues (soot, smog, smoke, flyash), construction (roads, buildings, vehicles), humans (proteins), fibers (lint), biological specimens (spores, pollen), soil (dust, salt) 	Some objects are difficult to clean (feathers, minerals, microcracks, sticky objects, etc.); Dust can cause disfiguration of objects, attract pests, and scratch soft surfaces by friction.
Water vapor 	Water vapor from visitors, water-based paints, and adhesives, wet cleaning activities and outdoor environment; 	Can produce both physical and chemical deterioration; fluctuations can damage wood products; hydrolysis of cellulosic materials including cellulose acetate and cellulose nitrate; objects with salts, gelatin, natural varnish are susceptible; causes oxides to convert to acids
== Synonyms and Related Terms ==
pollutants; air pollutants; pollution
==Resources and Citations==
* Jean Tétreault, "Sustainable Use of Coatings in Museums and Archives" Canadian Conservation Institute, 2011 [ https://www.morana-rtd.com/e-preservationscience/2011/Tetreault-05-01-2011.pdf Link]
* AIC Conservation Wiki: Exhibit Technical Notes: Environmental Control
* Exhibit Guidelines Technical Note: Monitoring Pollutants Inside an Exhibit Case
* Exhibit Guidelines Technical Note: Using Pollutant Absorbers Inside an Exhibit Case
* Jean Tétreault, Airborne Pollutants in Museums, Galleries and Archives: Risk Assessment, Control Strategies and Preservation Management. Ottawa, Canada: Canadian Conservation Institute, 2003.
* Cecily Grzywacz, Tools for Conservation: Monitoring for Gaseous Pollutants in Museum Environments. Los Angeles: Getty Publications. 2006.
* Elyse Canosa & Sara Norrehed; Strategies for Pollutant Monitoring in Museum Environments, Swedish National Heritage Board, 2019. Link
* Jean Tétreault, Agent of Deterioration: Pollutants Airborne Pollutants
* Pam Hatchfield, Pollutants in the Museum Environment, Archetype Press, London, 2002
* A Glossary of Paper Conservation Terms, Margaret Ellis (ed.), Conservation Center of the Institute of Fine Arts, New York City, 1998
* Art and Architecture Thesaurus Online, https://www.getty.edu/research/tools/vocabulary/aat/, J. Paul Getty Trust, Los Angeles, 2000
* Website: AMOL reCollections Glossary -http://amol.org.au/recollections/7/p/htm
Category:Materials databaseCategory: MWGCategory: Climate/EnvironmentCategory: Comparisons