LAUSR

Abstract Frequent dust storms originated from Middle Eastern deserts impact major cities in Iran, including Tehran. Previous studies identified Iraqi and Syrian deserts as the main cross-border contributors to Tehran Particulate Matter (PM) levels. In this study, the contribution of Iraqi and Syrian dust storms to Tehran's PM10 and PM2.5 concentration were assessed during a dust storm episode. Initially, a dust storm event was identified through the statistical analysis of the recorded air pollution data at Tehran's monitoring stations and the visual inspection of the satellite images. A combination of CMAQ/WRF/SMOKE modeling systems was used to simulate PM concentrations from Tehran local sources and dust storms formed in Iraq and Syria. An emission inventory of Tehran anthropogenic and biogenic pollutant sources was also developed and distributed throughout the city. In order to obtain the contribution of the different sources to Tehran PM10 and PM2.5 concentration, several sets of simulations were performed using different emission groups including local sources, Iraqi dust storms, Syrian dust storms and both Iraqi-Syrian dust storms. The results showed local emissions comprised most of the PM concentrations, however cross-border dust sources heavily influenced PM levels at all monitoring stations during the dust event. Nearly 28% of the average PM concentrations were dust particles formed in Iraq and Syria. The simulation of the dust event showed Iraqi's desert were responsible for nearly twice amount of observed PM concentrations in Tehran compared to Syria's desert during the episode. The results of this study could be used for planning effective measures to reduce dust related pollution problems in Tehran.