^{Peroxy Acetyl Nitrate does not have any natural presence but only be produced during human activity. Therefore, PAN is a significant representative index of photochemical pollution. System adopts GC-ECD principle to identify and quantify the presence of PAN in sample.} 

Photolytic rate of some critical reactant and free radical (O(1D), NO₂, H₂O₂, HONO, HCHO etc.) are key indicators for identify status & extent of photochemical pollution.The analyzer is receiving solar radiation by quartz probe and transferring the radiation to spectrum via optical quartz fiber, the spectrum data will be evaluated and compared with reference data with mathematical approach and gives photolytic rate.