The Research Institute for Environmental Health* operated monitoring stations 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 pollutants.
Days in the same month, which had approximately the same diurnal SI levels were grouped together. Half hour averages of SI and O3 were calculated for each group. These average values, obtained for the different 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 negative correlation with O3 pattern. This phenomenon was most outstanding during winter, especially in January, due to lower dispersion. There may 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 levels.
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 values.