This natural phenomenon affects ambient air quality, and it is estimated that it may contribute to an increase in suspended particle concentrations in the Algarve, Alentejo, Centre, North and Lisbon and Tagus Valley regions, explains the Portuguese Environment Agency (APA).

During today, according to the APA, the "circulation of the western quadrant close to the surface in mainland Portugal will gradually dislodge the dust-rich air mass", with the end of this episode expected on Thursday.

The APA explains that the long-distance transport of particles of natural origin in arid areas of North Africa, as is the case of the Sahara and Sahel deserts, can cause high levels of particles in suspension.

As long as this phenomenon continues, the DGS advises the population to avoid prolonged efforts, limit outdoor physical activity and avoid exposure to risk factors, such as tobacco smoke and contact with irritating products.

In addition to general recommendations, DGS advises the most vulnerable populations to remain inside buildings and, preferably, with windows closed. This population group includes children, the elderly, patients with chronic respiratory problems, namely asthma, and cardiovascular patients.