The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
An aerosol in the atmosphere of sufficient concentration and extent to decrease visibility significantly when the relative humidity is below saturation is known as haze. Haze may contain dry particles or droplets or a mixture of both, depending on the precise value of the humidity. In the use of the word, there is a connotation of some degree of permanence. For example, a dust storm is not a haze, but the coarse particles may settle rapidly and leave a haze behind once the velocity drops.
Human activity is responsible for many hazes. Enhanced emission of sulfur dioxide results in the formation of aerosols of sulfuric acid. In the presence of ammonia, which is excreted by most higher animals including humans, such emissions result in aerosols of ammonium sulfate and bisulfate. Organic hazes are part of photochemical smog, such as the smog often associated with Los Angeles, and they consist primarily of polyfunctional, highly oxygenated compounds with at least five carbon atoms. Such hazes can also form if air with an enhanced nitrogen oxide content meets air containing the natural terpenes emitted by vegetation.
All hazes, however, are not products of human activity. Natural hazes can result from forest fires, dust storms, and the natural processes that convert gaseous contaminants into particles for subsequent removal by precipitation or deposition to the surface or to vegetation. Still other hazes are of mixed origin, as noted above, and an event such as a dust storm can be enhanced by human-caused devegetation of soil.
Though it may contain particles injurious to health, haze is not of itself a health hazard. It can have a significant economic impact, however, when tourists cannot see scenic views, or if it becomes sufficiently dense to inhibit aircraft operations.
Air Pollution; Air Quality; Air Quality Criteria; Los Angeles Basin; Mexico City, Mexico
Husar, R. B. Trends in Seasonal Haziness and Sulfur Emissions Over the Eastern United States. Research Triangle Park, NC: U. S. Environmental Protection Agency, 1989.
Husar, R. B., and W. E. Wilson. "Haze and Sulfur Emission Trends in the Eastern United States." Environmental Science and Technology 27 (January 1993): 12–16.
Malm, W. C. "Characteristics and Origins of Haze in the Continental United States." Earth-Science Reviews 33 (August 1992): 1–36.
Raloff, J. "Haze May Confound Effects of Ozone Loss." Science News 141 (4 January 1992): 5.