by Maria Spiliopoulou, Valentini Anagnostopoulou

ATHENS, March 27 (Xinhua) -- The sky in many parts of Greece in the past few days has turned orange as waves of Sahara desert dust clouds have been sweeping through the country.

The phenomenon does not pose significant risks to public health, but Greeks should get used to it as it will become more frequent in the future, experts told Xinhua in Athens on Tuesday.

The natural phenomenon occurs for centuries in springtime and September as strong southern winds transfer sand from the Sahara to Europe all the way to Sweden some times, Nikos Michalopoulos, director of the Institute of Environment and Sustainable Development of the National Observatory of Athens and Chemistry Professor at the University of Crete, explained.

What has changed this March is that Greek citizens pay more attention as the concentrations of dust are quite high.

Last week the Athens Observatory recorded a 15 year record high in the city of Herakleion on Crete island, where the concentration of particulate matter pollution levels were 10 times of normal levels which the EU has set at 50 micrograms per cubic meter of air.

This week the level at Crete had dropped to about 200 micrograms per cubic meter and about 50 was recorded on Tuesday in Athens, but meteorologists warn that the circle is far from over.

"Maybe lately we put more emphasis, because now we take measurements, something that we did not use to do in the past," Michalopoulos noted. At the University of Crete the database started about 15 years ago.

Asked whether the natural phenomenon is affected by climate change, the Greek scientist noted that it was very early to reach conclusions. Experts need many years of research before answering this question.

"What we can say with certainty is that in the last five years we recorded a minor increase in the frequency of southern winds," he said.

"It is not clear whether climate change is a factor which could explain the increased frequency of such phenomena," the expert added.

"What we can say for sure is that climate change, given that models predict desertification in this region, will bring more dust which will be added to the dust clouds coming from northern Africa. Therefore in the future we will face higher concentrations of particles in the atmosphere than those we record today," he explained.

For the time being Michalopoulos suggests Greeks to be prepared for more dust this spring and take precautions if they have health issues.

"We must await more such phenomena until at least mid May," he said.

"It is wise when the measurements are showing more than 50 micrograms concentrations, and problems start for people - in particular those belonging to high risk groups, such as young children and patients suffering from cardiovascular and respiratory issues- then they should limit their exposure to the dust," he said.

Pulmonologist- Intensivist Panagiotis Bechrakis, Director of the Institute of Public Health of the American College in Greece, also suggested calm for the natural phenomenon which so far does not have significant impact on Greeks.

"The positive fact is that this cloud dust is not in particularly toxic. In case we faced similar concentrations of smog caused by human activities for so long, then the situation would be tragic," he explained.

People who do not have chronic health issues have nothing to worry about. Those with breathing problems are advised to stay indoors, use masks or a handkerchief to filter the larger particles of dust in the atmosphere and seek medical aid in case of discomfort.

"Undoubtedly every irritation that lasts for long has cumulatively consequences. However the rule so far is that these dust clouds come and go for a few hours or a couple of days. We do not have to deal with a permanent problem, therefore I do not see any reason why we should be alarmed that we may have chronic issues from this phenomenon," the Greek expert said.