"A situation of poor air quality is expected to occur on the continent, with an increase in the concentrations of inhalable particles of natural origin in the air, affecting the regions of the North, Centre, Lisbon, and Tagus Valley, Alentejo and Algarve", the DGS said in a statement.

According to the Directorate-General, this air mass carries suspended dust and is expected to cross mainland Portugal today with inhalable particles that have effects on human health, especially on the most sensitive population - children and the elderly - "whose health care should be redoubled during these situations".

The DGS recommends that the general population should avoid prolonged exertion, limit outdoor physical activity, and avoid exposure to risk factors, such as tobacco smoke and contact with irritants.

Children, the elderly, patients with chronic respiratory problems, such as asthma, and cardiovascular patients, due to their greater vulnerability to the effects of this phenomenon, should also remain indoors, preferably with the windows closed, whenever possible, the statement highlighted.

The DGS also states that chronically ill patients should continue with their medical treatments and, in the event of worsening symptoms, contact the Saúde 24 Line or seek medical help.