Volatile organic compounds , role

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

Many volatile organic compounds (hydrocarbons, alcohols, aldehydes, acids, esters, ketones, amines, etc.) have been identified in marine systems [ 156,157]. These volatile materials may have an important role in the cycling of organic... 

Solvents are widely used in the chemical industry and play a variety of roles e.g. mass and heat transfer (Adams et al, 2004). They are conventionally volatile organic compounds (VOC) that lead to significant emissions to the atmosphere and possess substantial risks such as flammability and toxicity. Some of these solvents are already banned in the pharmaceutical industry (e.g. benzene) and others... 

So what are nitrogen oxides Where does they come from And why is there a concern about the amount that enters the atmosphere Nitrogen dioxide (NO2) is a brownish, highly reactive gas that is present in all urban atmospheres. N02 can irritate the lungs, cause bronchitis and pneumonia, and lower resistance to respiratory infections. Nitrogen oxides are an important precursor both to ozone (Oj) and acid rain, and may affect both terrestrial and aquatic ecosystems. The major mechanism for the formation of NO2 in the atmosphere is the oxidation of the primary air pollutant, nitric oxide (NO). NOx plays a major role, together with VOCs (Volatile Organic Compounds), in the atmospheric... 

Gas-phase, solution-phase, and heterogeneous reactions all play important roles in atmospheric chemistry. The mean atmospheric composition is given in Table 1. N2, O2, and Ar comprise 99.9% of the atmosphere and, for all practical purposes, the relative proportion of these gases is constant in the lower 100 km of the atmosphere. We are concerned here with the fate of pollutants such as CO, volatile organic compounds, halocarbons, sulfur compounds, and nitrogen oxides, which are present in trace amounts and whose concentrations vary significantly both spatially and temporally. 

Brown HS. Bishop DR, Rowan CA. 1984. The role of skin absorption as a route of exposure for volatile organic compounds in drinking water. Am J Public Health 74 479-484. 

There is evidence of a cause-effect relationship between exposure to indoor (chemical vapours, gases [42], formaldehyde and volatile organic compounds) and outdoor pollution and induction of respiratory symptoms in individuals with established disease [43-45], However, the possible role of pollutants in the development of asthma and atopic airway disease seems less important and needs further elucidation. 

Abstract The possible utilization of room temperature ionic liquids (RTILs), instead of volatile organic compounds (VOCs), in the electrochemical procedures of organic synthesis has been discussed. The synthesis of p-lactams, the activation of carbon dioxide and its utilization as renewable carbon source and the carbon-carbon bond formation reactions via umpolung of aldehydes (benzoin condensation and Stetter reaction) and via Henry reaction have been selected as typical electrochani-cal methodologies. The results, related to procedures performed in RTILs, have been compared with those performed in VOCs. The double role of RTILs, as green solvents and parents of electrogenerated reactive intermediates or catalysts, has been emphasized. 

In the 1970s, the EPA assumed a leading role in pollution control. With the realization that practically all solvents exhibited some level of photochemical activity, new rules—state and national—were focused on the total solvent content of paints as applied. The index used—VOC (volatile organic compound)—did not differentiate between solvents or coalescents but merely set limits in pounds of emissions per gallon of paint (excluding water) for varying industrial applications. 

Solid sorbents play an important role for the determination of volatile organic compounds (VOCs) in indoor air. They overcome some serious disadvantages of liquid absorbents ... 

Three commercial processes, complete oxidation of volatile organic compounds (VOC) for purification of industrial exhaust gases, SO2 oxidation for sulfuric acid production, and NO reduction by ammonia, have employed the periodic flow reversal concept. In all cases the reaction Idnetics, including dynamic phenomena plays a crucial role. 

Chapter 3 Detection of Volatile Organic Compounds The Role of... 

D. Volatile organic compounds (VOCs), including low-molecular-weight alcohols, aldehydes, and ketones, are generated by molds, and are often responsible for the musty, disagreeable odor associated with indoor molds. A role for these VOCs in some building-related symptoms is possible. 

Low-molecular mass carbonyls are among the most abundant and ubiquitous volatile organic compounds in the atmosphere. They are produced from industrial activity and incomplete combustion of fossil fuels and biomass. Many aldehydes are also emitted indoors (plastic, foam insulation, lacquers, etc.). As a source of free radicals, aldehydes play an important role in the ozone formation, in urban smog events, as well as in the photochemistry of the unpolluted troposphere. Aldehydes are recognized irritants of the eye and respiratory tract, and often, carcinogenic and mutagenic characteristics are also attributed to them. 

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