Sahara Desert Sand allover the Swiss skies
On 6 February 2021, across parts of Switzerland, people awoke to a strange yellowish light and brown skies.
The strange light and brown sky are caused by sand from the Sahara desert. It is a well-known meteorological phenomenon that occurs around three times a year in Switzerland, according to SRF Meteo.
Areas currently most affected by it are in western Switzerland and include Geneva, Vaud, Valais, and Fribourg.
According to SRF Meteo, the sand came mainly from the northwest of Africa, a region containing Mauritania, Mali, and Algeria. Most of the sand is floating airborne between 2km and 5km from the ground, according to the weather service. It takes between a week and two days for the dust to travel from the desert to Europe. The largest particles land on the ground while the smallest remain airborne and continue their journey northward.
At the measuring station on the A2 motorway in Erstfeld, where we live, up to 140 micrograms of fine dust per cubic meter were measured. In Altdorf, the next large city, even a peak value of 214. That is about ten to twenty times more than under normal circumstances. But the absolute front runner was the measuring station on amazing Jungfrau Joch. This measuring station is located very high, 11,350 feet above sea level, and therefore measures practically no particulate matter under normal circumstances. On February 6th, however, she was in the middle of a cloud of dust. On Saturday afternoon, fine dust pollution of 768 micrograms per cubic meter was measured!
No health effects to be expected
The health effects of this short but high level of fine dust pollution are likely to be minor. Saharan dust can also act as a fertilizer. Especially in rainforests and partly in oceans it can be observed that nutrients get into the environment through regular input of Saharan dust.
The phenomenon accompanies a warm air weather system known as the Foehn.
