On Tuesday, March 15, half of Spain woke up dyed orange . There was dust everywhere, covering sidewalks, cars, upholstering patios… and suspended in the air. An extraordinary haze, which has reached even France and the Netherlands, was visiting us. How long will it last?
“The haze is a lithometeor, consisting of the suspension in the air of dry (non-aqueous) solid particles , such as mineral dust, of microscopic size, but in such quantities that they cause a significant reduction in visibility, making the sky look opalescent. , with a range of colors that can vary from ocher or earthy to orange and reddish, depending on the density of the particulate and the time of day”, tells us Jose Miguel Viñas, an expert at METEORED.
This orange dust comes, in this case, from the Sahara desert and it has been the Celia storm , installed in the southwest of our country and that has brought strong gusts of wind, the one in charge of transporting it directly to the Iberian Peninsula. Two types of haze are distinguished, the one that would be like the current one, that is, the one that is formed as a result of the dragging of sand from the desert and is called haze A and haze B, which has its origin in pollution and forest fires. . The A usually affects the Canary Islands and the B to cities that have a high level of pollution such as Madrid.
“In the absence of the episode ending, we can qualify it as extraordinary . Not so much because of the time of year in which it occurred, but because of the high density of particles and the extension of territory affected by the intense haze”, the meteorologist tells us. He also tells us that in the Canary Islands, where the haze phenomenon is very common, “there are many documented episodes of intensity similar to what is happening on the Peninsula.”
The haze of the Sahara that we have above us has detrimental effects on our health . As Viñas tells us, “the levels of PM particles in an FFP2 mask like the ones we use in the pandemic.” The worsening of the air has been noticed above all in Madrid, Barcelona and Valencia. In some neighborhoods of Madrid, on Tuesday morning, 500 microparticles (PM10) per cubic meter of air were exceeded, while in Almería it reached 600 PM10, according to data from Aqicn.
The good news is that the episode is expected to come to an end tomorrow, Thursday , and consequently the air quality will improve a lot in most of the country. “On Wednesday, a notable peak will be reached, predictably,” says the expert.
the Sahara desert
The Sahara desert occupies an area of more than 9 million square kilometers, most of North Africa . Its boundaries are diffuse, covering the entire African coast from east to west and reaching the Sahel belt to the south. In its extreme north its limit is gradual and reaches almost to the coast of Egypt, moving away about 500 km from the coast of Morocco.
As for the dust that comes from the Sahara, there are two fundamental sources of dust. One would be the Bodélé depression in northeastern Chad, which is also the most intense source of dust in the world, and the other the Tibesti mountain region in northern Chad. Depending on where they come from, dust particles can range from 0.7 µm (microns) to 20 µm.
“Saharan mineral dust has a significant proportion of iron, which is a good fertilizer , both from seawater and from farmland. The particles are also incorporated into the water cycle and are involved in precipitation processes. In general, a high concentration inhibits rain, but in smaller amounts it acts as an enhancer of it”, explains Jose Miguel Viñas. This rain that the meteorologist speaks of would be known as “rain of blood” or what is the same, when it seems that it rains mud and dirty everything in its path.