Particulate sulfate has been measured intermittently at various ground sites in Israel and from an instrumented aircraft for a 10-year period between 1984 and 1993. The measurements were accompanied by concurrent monitoring of primary and secondary air pollutants and meteorological parameters. In three studies, Etzion 1984, Jerusalem 1987, and Jerusalem 1990-1991 were taken for at least a year. The other studies were performed during summer months when higher levels of secondary pollutants, including particulate sulfate, were observed. In most of the studies samples were taken for four sequential 6-hour time segments. In one study, at Caesarea 1993, sulfate samples were taken only when wind flows were perpendicular to the coastline. The airborne measurements were performed along three north-south paths inside the planetary boundary layer, over the Mediterranean coast, over the Judea-Samaria mountains and over the Jordan Valley. Each flight path consisted of 30 to 45 minutes of continuous sampling of SO2 and one integrated sample of particulate sulfate. In all of our studies the concentration of particulate sulfate observed was relatively high compared .... 3 r with other world locations. The h•ghest values, occasionally exceeding 500 nmole rn , we e found during the summer. Wintertime levels were in the range of 50-100 nmole m '3. The annual average, calculated for the three long studies, is 100 q-15 nmole m '3, which is twice as high as predicted for the region by a global model and as high as reported for some of the more polluted regions in the US. Several indicators suggested that the origin of the sulfate in the region is not from local sources but the result of long range transport. The indicators include the lack of correlation between particulate sulfate and primary pollutants, the high sulfate to total sulfur values, the origin of the airmass back trajectories and the fact that similar levels were observed during concurrent periods at different sites. Throughout the study, higher concentration of particulate sulfate was found during the afternoon hours, especially during the summer and at the inland locations. The contribution to the afternoon elevated values could not be associated with long range transport and results probably from major sulfur emission sources located along the Israeli Mediterranean coast. of 1956-1987 [Stanhill and Moreshet, 1992]. This reduction might be attributed to the increasing particulate sulfate concentration in the region. Exposure to acidic aerosols may also pose a potential threat to health [Liang and Waldman, 1993; Waldman et al., 1993]. The possible association of fine particulates and sulfate and health effects was demonstrated by Dockery et al. [1993] in a study based on 15 years of air pollution and mortality data in six U.S. cities that indicated an increase of about 26ø/6 in mortality rate occurred in the more polluted of the cities (particulate sulfate long-term average concentration for the measuring period of about 13 gg m-3 or 135 nmole m-3), as compared with th...

Ambient particulate sulfate measurements have been intermittently performed at a rural site in Israel over a period of more than two years. Concurrent measurements of ambient pollutants (SO2, NO-NOx, and 03), as well as meteorological data, were also carried out. The daily data included four particulate sulfate samples representing four successive 6 h accumulating periods. The measured concentrations of sulfate ions ranged from a low 2 lag m -3 observed during the winter season to a high of > 50 lag m -3 obtained during the summer. Little correlation was obtained between the sulfate concentration and either 03 or SO 2 , although sulfate and 03 showed a similar diurnal and annual trend. Based on the data distribution and on a photochemical model, it was concluded that a large part of the particulate sulfate observed at the eastern coast of the Mediterranean Sea must be related to long-range transport from distant sources.