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Non methane hydrocarbons NMHCs are a major class of organic pollutants Xiao and Zhu 2003 Caselli et al 2010 that significantly affect atmospheric photochemical chemistry and human health Elbir et al 2007 Mudliar et al 2010 The NMHCs and oxygenated NMHCs e g alcohols aldehydes and organic acids are constituents of volatile organic compounds VOC that have short atmospheric lifetimes fractions of a day to months and have direct but small impacts on atmospheric radiative forcing Intergovernmental Panel on Climate Change https www ipcc ch ipccreports tar wg1 140 htm NMHCs have an important role to play on air quality due to their high reactivity that enables them to generate tropospheric ozone O3 through atmospheric chemical reactions with nitrogen oxides NOx and radicals under relatively high NOx concentrations Fehsnfeld and Liu 1987 Finlayson Pitts and Pitts 2000 Batterman et al 2005 As O3 in many areas could be NMHC dependent controlling NMHC emissions has assumed great importance and has been imposed to attain O3 standards Batterman et al 2005 In rural areas where NOx concentration is generally small O3 production is also less But in the urban areas due to the industrial and vehicular pollution the relative concentration of NOx reaches up to a level so that it easily contributes to production of O3 even in small concentration of NMHCs Donahue and Prinn 1990
