Naturally,Ozone (O3) is a gaseous molecule having a bluish colour with fishysmell. It is the natural constituent of the atmosphere with the pre-industrialconcentration of 10-15 ppb and present base line values of 30- 40ppb (Sitch etal., 2007) over globe were recorded. O3 is a secondary air pollutant formedfrom precursors such as NOx, NMVOCs, CH4 and CO in the presence of sunlight andthe process is called photochemical reaction. A brief description of the O3formation in the atmosphere with the initial breakdown of nitrogen dioxide(NO2) in the presence sunlight resulting in nitric oxide and nascent oxygen formation.
O3 is formed from reaction between nascent oxygen and molecular oxygen issummarized below as:NO2+ hv – NO + OO+ O2 – O3Nitricoxide (NO) react with O3 at low O3 concentration resulting in the formation ofNO2 and the process is called NO titration, is generally occur in urban areas (Mittalet al., 2007). The presence of Volatile organic carbon (VOC) and free radicals,consumes NO thus more O3 concentration in the atmosphere (especially ruralareas) has been recorded. At the same time, less diurnal variation was observedin the rural areas because of low NOx concentrations (Mittal et al., 2007). Thetotal O3 concentration in the atmosphere is contributed mainly by in-situ photochemicalreaction among O3 precursors (Sahu et al., 2016) and downward movement fromstratosphere (Lefohn et al.
, 2011). HTAP includes NA, EU, SA and EA in northernmid-latitude conclude that in these region, the total atmosphere O3 contributesby aprox. 25% from stratosphere, aprox. 25% originated from natural sources andrest 50% released from anthropogenic activity. Out of 50% anthropogenicaddition, 20% generated in-situ by photochemical reaction while 25% aretransported through air masses from others polluted places. In the anthropogenicaddition, human activities play significant role in increasing surface O3(TFHTAP, 2010). Ambient O3 concentrations contributed by anthropogenicactivities are variable, reducing in EU and NA but increasing in EA (Granier et al.
, 2011). At the same time, changesreported from high to low latitudes NH (Parrish et al., 2013). Ground level O3concentration in East Asia has been increasing due to high precursor emissioncontributed by human activities and more developing countries (Cooper etal., 2014). Combustion of fossil fuel and biomassburning are the major source of O3 precursor particularly in India ( Sinha et al., 2014).
India reportedhigh O3 concentration in which highest O3 concentration typically high indensely populated Indo-Gangaetic Plain of northern India. Exceptionally high O3concentration was recorded in the China in june month with 30-60% high O3 and3-4 times more CO compared to others sites (Zbinden et al. (2013).Humanplays major role in biomass burning which are roughly equal in both thehemispheres (Dentener etal., 2011). Biomassburning global emission of NOx (main precursor of O3) from the fossil fuel andbiomass burning for the year 2005 was reported (Van der Werf et al.
, 2006). Inaddition to this, transboundry movement of O3 precursors from the developingcountries contributes to increasing in background O3 concentration (Dentener etal., 2006). . O3 concentration throughout the year is not uniform dependingupon the meteorology and precursors at a particular region, therefore,troposphere O3 is a regional and global (hemisphere) scale pollution. O3 is agreenhouse gas with the radiative force of 0.
35 Wm-2 absorbingradiation at 9.4 µm wavelength reflected from earth surface (Solomon et al.,2007). O3 along with many others factors such as increasing temperature andelevated CO2 results in climate change (Gilliland et al., 2015).