“There is an intrusion of an air mass coming from the deserts of North Africa, resulting in a situation of poor air quality with high levels of inhalable particles (PM10)”, says the Portuguese Environment Agency (APA), in a statement.

The APA advances that the occurrence started early this morning in the North region, and is expected to extend to the regions of the Center, Lisbon and Vale do Tejo and Alentejo, and the rest of the country on Wednesday.

According to the APA, the dust clouds should decrease in intensity from Thursday.

The APA explains that this is “a phenomenon that occurs when the air mass containing high concentrations of dust is transported over large distances from arid and semi-arid regions, reaching lower altitudes, reaching ground level, as is the case in the situation that is already taking place in the interior North region of the country”.

The Portuguese Environment Agency also indicates that “this pollutant has effects on human health, mainly on the most sensitive population, children and the elderly, whose health care must be redoubled during the occurrence of these situations, and the specific recommendations of the Directorate-General must be followed".