El saharan dust It is found in numerous cities near the Sahara Desert. We know that gusts of wind can carry sand particles, which end up being deposited in different locations. This dust can cause various problems in people's daily lives and can benefit some natural ecosystems.
In this article we are going to see what Saharan dust consists of, what its characteristics are and how it harms or benefits the environment and people.
What is Saharan dust
It is particulate matter suspended in the atmosphere in the Sahara desert and transported by the winds to other regions. Its presence in the atmosphere can cause some turbidity in the sky and, in some cases, significantly reduce visibility. Furthermore, sunsets with yellow or reddish skies are also common in the presence of suspended dust, as can be seen in the sunsets associated with Saharan dust.
When precipitation occurs in the presence of suspended dust, we deposit wet dust in the form of mud rain (or blood rain). Dry settling occurs when particle concentrations are high and particles fall to the surface by gravity.
Saharan incursions are often referred to as smog or simply airborne dust. However, other particulate matter from different sources (factories, fires, etc.) can generate mist (very small solid particles in suspension). Specifically, Saharan dust constitutes a type A haze or natural haze.
Composition and transportation
The dust in the Sahara It is made up of different mineral compounds found on the surface of desert sand. Silicates (muscovite, quartz, kaolinite, etc.) and carbonates (such as calcite or dolomite) are in the majority.
In Spain, Saharan dust is most often found in the Canary Islands. This occurs when easterly winds manage to blow away dust from the desert, leaving cloudy skies and very poor air quality on the islands, especially the easternmost ones. This phenomenon is more common in winter in the archipelago.
However, Saharan dust intrusions are also more frequent in the Iberian Peninsula, especially in the southern and eastern half of the peninsula. Here, the events occurred near a deep depression near the west, which was blowing southerly winds and carrying dust from North Africa. They can also occur when DANA is in the northern part of the continent, and winds channeled from the southeast can also leave mud rain, as seen in Recent events.
The haze caused by Saharan dust disappears as winds and air masses change, transferring the dust to other areas.
How is Saharan dust measured?
All these types of small suspended particles belong to the PM10 and PM2,5 groups (particles less than 10 microns and 2,5 microns in diameter, respectively) and are commonly used to determine air quality. Therefore, these records are used to understand the concentration of Saharan dust in the atmosphere.
Airborne dust tends to worsen the AQI, especially PM10. In Spain, the daily limit of PM10, harmful to health, is set at 50 µg/m3. In cases such as the Kalima event in March 2022, values of up to 1000 µg/m3 were found in large areas of the peninsula.
Furthermore, thanks to the Barcelona Dust Forecast Centre, managed by AEMET and the Barcelona Supercomputing Centre, daily forecasts of suspended dust in Europe are available. If you'd like to learn more about the implications of this phenomenon, you can read the article on the intrusion of Saharan dust and its impact.
Benefits and harms
The negative effects of airborne dust in the Sahara desert are associated with worsening air quality. This mainly has direct effects on health, such as respiratory problems and irritation of the mucous membranes. Also, intense concentration can make it difficult for some people to breathe and even develop anxiety.
However, many people are unaware that the haze events associated with the Saharan dust invasion also have a positive side. Their mineral salt and metal content serves as a natural fertilizer for agriculture and fishing in the areas where these particles are deposited, which can be considered a significant benefit. When this phenomenon occurs in high concentrations, it is recommended to go out as little as possible and always wear a mask to avoid inhaling these particles. It is recommended to avoid physical activity outdoors. In interior spaces, it is important to keep the windows closed.
haze and Saharan dust
This is a meteorological phenomenon that occurs in the atmosphere and is characterized by the presence of very small solid particles in suspension, but in sufficient quantities to give the air an opaque appearance. Yes, it is sand floating in the air.
As a result, we observe cloudy environments and yellowish or orange colors. These particles are usually dust and sand, but can also form ash and clay fog, in which case the particles are much smaller in size, in units of microns and tens of microns. It must be emphasized that long-term inhalation of these substances is detrimental to health.
Etymologically we find that in Latin, caligo y caliginis, are words that translate as “black smoke”, “cloud”, “opaque and black fog” or “dense dust”, so clearly, haze is not a new phenomenon, the Romans already gave it a word.
It is important do not confuse smog with haze, which can also reduce visibility, but make a big difference due to humidity. Unlike smog, which consists of solid, dry particles in the air, fog and mist are water particles in the environment, and very humid air does not have negative health effects, unlike smog.
The most common place to find haze in Spain is the Canary Islands, but not because it occurs there. The origins of calima are large deserts, such as the Sahara desert in the Canary Islands.
For this to happen there must be two climatic factors: a desert dust storm and southerly or easterly winds that drag the dust storm to the Canary Islands or the peninsula itself, as happened in March 2022.
I hope that with this information you can learn more about Saharan powders and their characteristics.