Urban Planning, Ecological Transition, Urban Services and Housing

Tropospheric ozone levels are forecast to be high in the coming days. People are advised to reduce intense physical activity, especially outdoors, and particularly vulnerable groups. On Monday, 30 June, the Government of Catalonia’s Directorate General for Environmental Quality and Climate Change activated the preventive alert for high levels of ground-level ozone, or tropospheric ozone, which may affect the respiratory system of the most vulnerable.

What is tropospheric ozone?

Tropospheric or ground-level ozone is a pollutant that forms from a photochemical reaction between nitrogen oxide (NO2), volatile organic compounds (COVC) and intense solar radiation over several hours. Because of this, ozone levels increase during the summer with the increase in temperatures, particularly at weekends, when nitrogen oxide (NO2) emissions from cars drop.

This pollutant should not be confused with the ozone in the higher layers of the atmosphere, which protects us from ultraviolet radiation from the sun.

How does ground-level ozone affect our health?

Breathing in high levels of ozone can cause irritation to the throat and eyes, coughing and a sensation of a dry throat. It can make respiratory symptoms worse in people with asthma or other chronic respiratory illnesses.

High concentrations of ozone increase the risk of developing asthma or chronic pulmonary obstruction, and of reduced pulmonary operation. People particularly sensitive to the effects of ozone include those with respiratory or heart conditions, the elderly, infants or pre-school age and pregnant women.

More updated information on ground-level ozone levels in the city at: https://canalsalut.gencat.cat/ca/detalls/article/ozo-troposferic-00002.