This Sunday, ozone levels in northern Portugal exceeded safety thresholds, prompting a warning from the CCDR. The concentration reached 186 µg/m³ at the Burgães station, surpassing the 180 µg/m³ threshold. Vulnerable groups, including children and the elderly, are advised to avoid outdoor activities and seek medical help if symptoms arise. The ozone is a secondary pollutant formed from reactions between other pollutants and solar radiation, with higher concentrations occurring in summer afternoons. Authorities have declared a state of alert due to high temperatures and active fires in the region.