air pollution assessment in shiraz by passive sampling techniques

the air quality in shiraz was assessed based on a one-week passive sampling campaign.during the first week of the summer 2003, about 400 passive samplers were used in groups of two andthree, so that 187 sampling stations covered all of shiraz. pollutant gases including so2, no2 and btx(benzene, toluene and xylene) were sampled by diffusive sampling tubes. collected samples wereanalyzed and pollutant concentrations were determined by using ion chromatography, spectrophotometryand gas chromatography techniques. the result of the analysis shows that so2 and no2 concentrationsexceed national and international standards in the central and southern parts of shiraz. weekly averagedconcentrations of benzene, toluene and xylene at all sampling sites were 105, 206 and 123 μg/m3, whichexceed national and international standards.based on the results, more than 15% of shiraz's population (180,000 out of 1.2 million people)were exposed to high levels of no2 during this survey period.