The immense fallout throughout Europe of ash and dust from Iceland’s still-erupting volcano Eyjafjallajokull does not pose health dangers to the populations underneath but rather to aircraft flying above the continent.
Because too little is known about what concentrations of the microscopic debris in the upper atmosphere could cause serious harm to jet engines and windshields, the airlines are playing it safe and keeping planes away until the dust settles, according to Israeli experts in jet engines and atmospherics.
The only harm Israelis could suffer at this point is logistical and economic, either from delayed flights to and from Europe or from the inability to get Israeli produce and goods to their European markets.
Dust from ordinary sand storms are close to the surface and thus affect old and sick people, children and pregnant women, but the volcanic particles are at a high altitude and far to the west, so no one is in danger.
Prof. Daniel Rosenfeld, a Hebrew University of Jerusalem expert in rain and cloud physics, precipitation formation processes and satellite and radar analysis of the volcanic thunderstorms, among others, told The Jerusalem Post
Sunday that volcanic dust is very similar to dust that reaches Israel from African deserts during a hamsin
but even smaller.
The problem is not on the surface, but six to 10 kilometers upwards, where jet planes fly.
Though many believe such an extraordinary event has never happened in modern times, they are wrong, he said. The Pinatubo volcano eruption in the Philippines in 1991 caused harm to planes, though none crashed.
But that volcano was far from major airline traffic routes, unlike the current volcano. However, it is true that the expanse over which the volcanic ash has spread is unprecedented, and the volcano has not yet halted its spitting of particles into the atmosphere, he said.
The volcano is only about a kilometer high, added Rosenfeld, but the heat causes the particles to be propelled upwards at great force, causing them to reach the upper atmosphere. Satellites can view the dark accumulations of microscopic glass particles, but it could be necessary for pilots in jets devoid of passengers to fly to the altitude with special sensors to collect particles and determine their concentrations.
“There are things that are beyond our power,” he said. “The particles can’t be filtered out of the atmosphere or blown away, except by the wind.”
Dust in the lower atmosphere, where rain clouds are located, can be brought down by precipitation, but most of particles are above the clouds, so they could remain there for a much longer time while losing their density, he said.
Israel does not have volcanoes, though the Golan had volcanic activity some 10,000 years ago, and the basalt residue in the north is evidence of it, Rosenfeld said.
“They have not been active for a very long time. But Iceland is an island that was created by volcanoes, and these are still active,” he explained.
Hebrew University air pollution and atmospheric chemistry expert Prof. Menachem Luria added that the volcanic particles can spread over the entire globe via the winds, but the farther they are from the volcanic source, the less dense they are.
“It’s hard to predict where they will go, as there is no real model for this,” he said. “The density over Europe is 10 times or more the level of desert dust in this region during a hamsin. When the particles fall to earth, they will dissolve in the rain.”
They are not toxic and cause no harm to agriculture, but they do not benefit agriculture either, said Luria.
The particles can cause damage to jet planes in a number of ways, said Prof. Yeshayahou Levy of the Technion-Israel Institute of Technology in Haifa.
The expert in aircraft engines said that the particles are very abrasive due to their speed. Entering a jet engine, they can harm the engine blades and change their dynamic shape. Harm to the exterior flaps that change the plane’s direction is less significant, he said.
In addition, the pilot’s windshield can be hit by the particles and severely scratched, making the glass cloudy. Static electricity can be produced and sensors can be blocked. All the plane’s jet engines can stall.
Particles going through the engines’ compressors into the combustion chambers would meld and conglomerate, causing buildup and blocking the turbine.
“While it is theoretically possible to restart stalled engines, this is not a likelihood,” said Levy.
Jet planes flying at high altitudes are not designed for an encounter
with such dust, he explained, as particles block channels within the
turbine blades, which have to be constantly cooled by air. If blocked,
they will get very had, become plastic and break the engine.
Planes will have to stay away at least until the volcano shuts down, he declared.
helicopter engines – which are often exposed to dust particles – are
built to function in dust, and they have an integral air particle
separator. Jet planes could theoretically be designed to carry such
equipment if the volcanic ash remains at their altitude for some time,
but engine performance would decline, said Levy, and it would be very