Air pollution from North Africa and Europe containing toxic materials has reached Israel, according to a series of studies by the Hebrew University and the Weizmann Institute of Science.
Tests show that toxic materials also get here on particles of desert dust.
Researchers will present a report at the President's Conference in Jerusalem on Tuesday, held jointly with the Hebrew University.
Scientists have been studying air particles arriving in Israel for years, and it is known that pollution can move long distances. But only in recent years has a precise analysis been made of the pollution and its origins.
The meteorologic data indicates that for two thirds of the days of the year, air currents arrive from Western and Eastern Europe, and for more than one-fifth of the year, air currents arrive from Saudi Arabia, Jordan and North Africa.
One of the project's key discoveries is that desert dust, which had been considered a natural and ostensibly less toxic pollutant, contains man-made materials that endanger health.
"We found that the desert dust we examined in Jerusalem contains both toxic metals and pesticides," said Prof. Yigal Erel, a researcher in the project.
Erel said the pollutants come from polluted soil in deserts; for example, in Egypt, and may also come from industrial activities around Cairo.
The researchers, who took air samples during dust storms, found that during several summer days, dust particles are present in Israel that originated in Europe and contain heavy metals such as nickel, zinc and lead. More than half of these metals accumulate in the dust while it is still in Europe. Lead was found in the dust that had originated in Ukraine, along with lead originating here.
According to the Hebrew University, air samples from the Beit Shemesh area reveal that more than half the larger pollution particles come from hundreds of kilometers away, or more.
Tests found that on cooler summer days, pollution from Europe is greater than local pollution, in relative terms.
Pollution from Israel also reaches neighboring countries. According to one study, it is very likely that air pollution created by bonfires during the Lag Ba'omer holiday makes its way to Amman, Jordan.
Researchers say work to improve Israel's air quality is not enough to prevent the health risks associated with pollution. They urge the adoption of conventions that will oblige all countries in the region to improve the situation.
Egypt, for example, should be encouraged to enforce clean-air laws, the researchers say, adding that countries share a common interest in reducing air pollution, which causes many hundreds of deaths every year.
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