SURFACE OZONE levels breached safety levels in at least five areas of Lisbon on Tuesday of last week, a day when temperatures reached 36 centigrade.
In Almada, Lisbon, Loures, Odivelas and Sintra, levels exceeded 180 microgrammes per cubic metre (mg/m3), the point at which authorities are obliged to warn the public of health risks. Ultraviolet levels were also extremely high.
“Ozone is a secondary pollutant and a form of oxygen resulting from car emissions and from combustion in industry,” says environmental group Quercus. The organisation says that “in the stratosphere, ozone is beneficial, but nearer to the ground it can be very prejudicial”. The Commission of Co-ordination and Regional Development (CCDR) for Lisbon and the Vale do Tejo recorded the highest levels in Olivais (206 mg/m3) and Restelo (193 mg/m3) between 1pm and 2pm.
Avoid exposure in polluted areas
The recent heat wave, which particularly affected the capital, inevitably triggers increases in ozone levels on the ground. The Assistant Director-General of Health, José Robalo, said that high ozone levels could trigger respiratory problems and eye irritation. Other symptoms include coughing, headaches and chest pains, particularly among vulnerable groups such as the elderly, children and the sick.
Robalo recommended that people should “avoid prolonged exposure to the sun, especially in highly polluted areas, as well as physical exertion outdoors,” which could aggravate their symptoms.
The Meteorological Institute also issued alerts last week about levels of ultraviolet reaching “extreme values” between 1pm and 2pm. The president of the institute, Adérito Serrão, advised caution: “The situation is normal bearing in mind the high temperatures recorded, but an exposure above 14 minutes can cause burns.”