Abstract
Volatile Organic Compounds (VOCs) present a particularly unique testing dilemma sincethere are a large number of different compounds defined as VOCs, The process of accuratelyand consistently measuring the quantity of total VOCs emitted is a matter of concern to policymakers and researchers,Each method has advantages and disadvantages relative to the other methods, The choice ofmeasurement and reporting techniques depends on the purpose that the data will serve, Due todiffering analytical limitations for each of the VOC test methods, all sources may not be ableto use the same method/ procedures to monitor and report,Because of the wide variety of compounds of interest coupled with the lack of standardizedsampling and analysis procedures, detennination of pollutants in ambient air is a complextask, Many toxic organics can be sampled and analyzed by several techniques, with differentinterferences and detection limitations, No uniforn1 averaging period is defined for ambientvoe measurement,
Highlights
Volatile Organic Compounds (VOCs) are major class of pollutants causing concern, VOCs are part of the large hydrocarbon family, a vast array of aliphatic, aromatic hydrocarbons, their halogenated derivatives, alcohols, ketones and aldehydes, VOCs have a property of conversion into vapour or gas without any chemical change, They are highly reactive hydrocarbons and participate in atmospheric photochemical reactions, Some of them have negligible photochemical activity; they play an important role as heat trapping gases in atmosphere, Sources: Many VOCs are of natural origin while many owe their existence to anthropogenic activities, Natural sources of VOCs include forests, tem1ites, oceans, wetlands, Tundras and volcanoes, Estimated global emission rate of biogenic VOCs is 1150 Tgyr-1 (Guenther et al,J 995)
The anthropogenic sources of VOCs consist of vehicular emissions, petroleum products, chemicals, manufacturing industries, painting operations, varnishes, coating operations, consumer products, petroleum handling, auto refinishing, cold clean degreasing, printing inks, dry-cleaning etc, In presence of oxides of nitrogen and sunlight, VOCs fom[1] ozone and other products, Oxidation of VOCs by reaction with hydroxyl radicals is the main removal process, The oxidation of complex organic molecules leads to the fragmentation, production of a range of reactive free radicals and more stable smaller molecules such as aldehydes, VOCs are cause of concern firstly due to its role in formation of ground level ozone and smog and secondly due to some of them being carcinogenic, mutagenic and teratogenic in nature, Adverse effects
UNECE Definition/ Environment Agency voe as any organic compound which is emitted from anthropogenic processes and has a photochemical ozone creation potential (POCP) excluding methane and naturally occurring voes
Summary
Volatile Organic Compounds (VOCs) are major class of pollutants causing concern, VOCs are part of the large hydrocarbon family, a vast array of aliphatic, aromatic hydrocarbons, their halogenated derivatives, alcohols, ketones and aldehydes, VOCs have a property of conversion into vapour or gas without any chemical change, They are highly reactive hydrocarbons and participate in atmospheric photochemical reactions, Some of them have negligible photochemical activity; they play an important role as heat trapping gases in atmosphere, Sources: Many VOCs are of natural origin while many owe their existence to anthropogenic activities, Natural sources of VOCs include forests, tem1ites, oceans, wetlands, Tundras and volcanoes, Estimated global emission rate of biogenic VOCs is 1150 Tgyr-1 (Guenther et al,J 995). International concerns regarding voes arise due to their ability of long range transport, distribution and accumulation in various components of environment, their toxic nature and significant contribution from natural sources
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