Benzene’s concentration in the atmosphere is derived from the rate of its emission and the atmospheric conditions that cause it to be dispersed and transported. An analysis of the daily benzene concentrations in the three largest population centers in Israel (Tel-Aviv, Jerusalem and Haifa) revealed that practically all values were lower than the Israeli 24-h air quality standard. Even though, daily elevated benzene occurrences were found to be associated with four out of the 22 synoptic weather types prevailing over the Eastern Mediterranean, more than half of them occurring during the winter and the transitional seasons. These weather types are characterized by a persistent south-easterly dry flow over Israel. During nighttime the very high frequency of the radiative inversion characterizing these 4 synoptic types trap the benzene near the surface, resulting in elevated concentrations. At daytime, a significantly higher relative frequency of weak winds was found for the four relevant synoptic types, as compared to their overall relative frequency. These calm conditions contribute to the observed buildup in the benzene concentrations. The very high prevalence of both radiative inversion during the nights and weak winds in daytime for the four synoptic circulation types did not alter the strength of the synoptic classification in predicting the prevalence of these elevated benzene occurrences. The annual frequency of benzene elevated concentrations is about 30 percent, mostly associated with the presence of the two modes of the Red Sea Trough. Therefore, synoptic classification can serve as a valuable predictor of elevated concentrations. 

Sarit is a Lecturer of Statistics at Hebrew University. Her research focuses mainly on survival analysis, measurement error, and topological data analysis, but on various applied statistics in different areas, such as air pollution, as well. Sarit have completed an MA in Economics and Statistics at Hebrew University, and earned her PhD in Statistics at Hebrew University. Her MA and PhD theses discussed the setting of a changepoint with or without a measurement error in the main covariate, in modeling a survival time. In her postdoc at the Technion-Israel Institute of Technology, she worked on Topological Data Analysis.