Saharan Sand Cloud from Morocco to Worsen Air Quality in Belgium

"It happens that Saharan sand is transported to Europe, it is quite regular. In winter, it often affects Spain, the Canaries for example, and it can happen that this sand is brought up to above our regions," says Philippe Maetz, expert of the interregional environmental cell, Celine with La Libre. According to him, this is not very frequent, but it does happen. "So it also contributes to pollution since it is added to our own emissions. But the sandstorm will rarely be the sole cause of the pollution peak. We are far from it!" he explains. Recalling an episode in January in the Canaries, the specialist says that "this phenomenon of importing Saharan sand is called the Calima, from the name of a specific wind that carries the sand over the Canary Islands." This type of event "is not so rare and can occur several times a year," explains the Royal Meteorological Institute (IRM), adding that Belgium will not be spared from the Saharan sandstorms.

"The dust in the air limited visibility, the cars were yellow, and the concentrations in the air were enormous: 200 or 300 micrograms per cubic meter, or even more. This doesn’t happen here of course. Nevertheless, we occasionally observe imports of sand or sand dust from the Sahara," adds Philippe Maetz, stressing that it is very rare for a pollution peak to be attributable to a single source. "We always measure fine particles as a set of compounds that are never very well defined: there are organic compounds in it, such as pollution coming from road traffic or heating, and mineral compounds, such as dust raised from the ground. Indeed, soil erosion is also a natural source (of air pollution). Wind or traffic stir up dust on the ground, but of course it is not as important as if we were in a desert!" continues the expert.

He says that weather conditions must also be added to this: a stable weather where particles are not dispersed. "The sand that will come from the Sahara to here will be added to a pollution episode, and can sometimes constitute a significant part of the episode, but it will never be alone. It is also difficult to say whether this element has a greater impact than the other sources, a pollution peak always being a mixture of different things. This is not currently the most important source of fine particle pollution. Local emissions related to residential (heating) and traffic remain by far much more important than the contribution of Saharan sand imports," summarizes Maetz.

What about the impact of this Saharan dust on health? According to the Copernicus Atmospheric Monitoring Service (CAMS), it depends on the concentration and altitude. "It has been established that high concentrations of dust, generally close to the source of the dust, cause respiratory and cardiovascular diseases. The transport of dust at high altitude is less likely to have a significant impact on surface air quality. But significant surface dust clouds bring coarse and fine particles, deteriorating air quality and posing respiratory, even cardiovascular, risks," he explains, adding that these episodes can also carry viruses or bacteria from the dust sources. CAMS estimates that this sand can also be radioactive. And to reassure: "The source can be natural and, in the case of a particular region of Algeria, from the nuclear tests carried out by France in the 1960s. Again, there is no evidence that at these concentrations, the particles could pose a risk to health or the environment."