background: nitrogen oxides occur in the atmosphere in six forms of namely: n2o , no , no2 , n2o3, n2o4 and n2o5 .among these oxides no2 is the most important air pollutant because of its relatively high toxicity and its ubiquity in ambient air. in this research griess-saltzman method was utilized for determination of nitric oxide and nitrogen dioxide in the atmosphere of different laboratories...