Air pollutants, general

Examples of point sources of air pollution, general control methods, and pollution prevention and energy saving practices... 

VDI 2262/ Blatt 1, April 1993. Luftbeschaffenheit am Arbeitsplatz, Minderung der Exposition durch luftfremde Stoffe Allgemeine Anforderungen (Workplace Air, Reduction of Exposure to Air Pollutants—General Requirements). 

Air pollution—generally, local environmental agencies are quick to arrive at industrial fires and start monitoring to determine if hazardous materials are in the air that could cause harm to the public or the environment. Depending on the materials on fire, there is a potential for hazardous materials to travel offsite. The Emergency Response Plan must identify potential pollutants and appropriate responses for the public. 

In the United States, antimony is listed as a Clean Air Act hazardous air pollutant generally known or suspected to cause serious health problems. Antimony and its compounds are listed as Clean Water Act... 

Nickel chloride is listed as a US hazardous air pollutant, generally known or suspected to cause serious health problems. The Clean Air Act, as amended in 1990, directs the US Environmental Protection Agency (EPA) to set standards requiring major sources to sharply reduce routine emissions of toxic pollutants. EPA is required to establish and phase in specific performance based standards for all air emission sources that emit one or more of the listed pollutants. Nickel is also a toxic pollutant designated pursuant to Section 307(a) (1) of the Clean Water Act and is subject to effluent limitations. 

Temperature also affects the response of vegetation to air pollution. Generally, plant sensitivity to oxidants increases with increasing temperature up to 30°C. Soybeans are more sensitive to ozone when grown at 28°C than at 20°C, regardless of exposure temperature or ozone doses (Dunning et al. 1974). The response of pinto bean to a 20 and 28°C growth temperature was found to... 

The air pollutants generally determined may be grouped into five categories [9 ... 

The pneumatic classification system should be designed to handle ha2ardous dust (28). A ha2ardous dust is one which, when finely divided and suspended in air in the proper concentration, bums, produces violent explosions, or is sufficiently toxic to be injurious to personnel health (see Air pollution control methods Powders, handling). At the least, almost any dust can be irritating to personnel because of inhalation or skin or eye contact. Fully oxidi2ed and hydrated materials are generally considered safe. 

Air pollution problems and labor costs have led to the closing of older pyrometaHurgical plants, and to increased electrolytic production. On a worldwide basis, 77% of total 2inc production in 1985 was by the electrolytic process (4). In electrolytic 2inc plants, the calcined material is dissolved in aqueous sulfuric acid, usually spent electrolyte from the electrolytic cells. Residual soHds are generally separated from the leach solution by decantation and the clarified solution is then treated with 2inc dust to remove cadmium and other impurities. 

Pressure drop in a venturi scrubber is controlled by throat velocity. While some venturis have fixed throats, marw are designed with variable louvers to change throat dimensions and control performance for changes in gas flow. Pressure-drop equations have been developed by Calvert (R-13, R-14, R-15), Boll [Ind Eng Chem Fundam, 12, 40 (1973)], and Hesketh [J. Air Pollut Control Assoc, 24, 939 (1974)]. Hollands and Goel [Ind Eng Chem Fundam, 14, 16 (1975)] have developed a generalized pressure-drop equation. 

Unbumed Hydrocarbons Various unburned hydrocarbon species may be emitted from hydrocarbon flames. In general, there are two classes of unburned hydrocarbons (1) small molecules that are the intermediate products of combustion (for example, formaldehyde) and (2) larger molecules that are formed by pyro-synthesis in hot, fuel-rich zones within flames, e.g., benzene, toluene, xylene, and various polycyclic aromatic hydrocarbons (PAHs). Many of these species are listed as Hazardous Air Pollutants (HAPs) in Title III of the Clean Air Act Amendment of 1990 and are therefore of particular concern. In a well-adjusted combustion system, emission or HAPs is extremely low (typically, parts per trillion to parts per billion). However, emission of certain HAPs may be of concern in poorly designed or maladjusted systems. 

The air pollution problems associated with combustion of coal are of major concern. These problems generally occur away from the coal mine. The problems of atmospheric emissions due to mining, cleaning, handling, and transportation of coal from the mine to the user are of lesser sigruficance as far as the overall air pollution problems are concerned. Whenever coal is handled, particulate emission becomes a problem. The emissions can be either coal dust or inorganic inclusions. Control of these emissions can be relatively expensive if the coal storage and transfer facilities are located near residential areas. 

A mobile source of air pollution can be defined as one capable of moving from one place to another under its own power. According to this definition, an automobile is a mobile source and a portable asphalt batching plant is not. Generally, mobile sources imply transportation, but sources such as construction equipment, gasoUne-powered lawn mowers, and gasoline-powered tools are included in this category. 

In general, clinical studies provide evidence on the effects of air pollutants under reproducible laboratory conditions. The exposure level may be accurately determined. The physiological effect may be quantified, and the health status of the subject is well known. This type of study can determine the presence or absence of various endpoints for a given sample group exposed to short-term, low-level concentrations of various air pollutants. 

In general, air quality data are classified as a function of time, location, and magnitude. Several statistical parameters may be used to characterize a group of air pollution concentrations, including the arithmetic mean, the median, and the geometric mean. These parameters may be determined over averaging times of up to 1 year. In addition to these three parameters, a measure of the variability of a data set, such as the standard deviation... 

Wind speed generally increases with height. A number of expressions describe the variation of wind speed in the surface boundary layer. A power law profile has frequently been used in air pollution work ... 

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