THE CORRELATION BETWEEN SOILING INDEX AND ATMOSPHERIC OZONE CONCENTRATIONS IN TEL-AVIV

The Research Institute for Environmental Health operated monitoring s tations for the measurement of air pollutants emitted by combustion in Tel-Aviv. Most of the soiling index (SI) data obtained for the years 1976-1985, showed a direct correlation with the other primary pollutan ts. Days in the same month, which had approximately the same diurnal S I levels were grouped together. Half hour averages of SI and O3 were c alculated for each group. These average values, obtained for the diffe rent groups of SI, were compared. The resultS showed that groups with high SI levels had low O3 values and vice versa. Also weekends, which had low SI levels, due to lower traffic, had higher O3 concentrations as compared to other days of the week. SI values showed a clear negati ve correlation with O3 pattern. This phenomenon was most outstanding d uring winter, especially in January, due to lower dispersion. There ma y be a direct influence of soot on the O3 concentrations, or it may be that the SI is only an indicator of the total reducing pollutants lev els. It was also found that for high SI values, the slopes around the O3 peak were steeper than those obtained at low SI levels. O3 levels, except those at the peak were close to zero on days with high SI value s.