Almost the entire population residing in Spain (specifically, 96.5%) and 99.5% of the national territory have been exposed this year to levels of unhealthy air due to tropospheric ozone (O3) thanks largely to high temperatures, Well, this spring was the warmest in the country since at least 1961 and the summer turned out to be the third hottest, only behind those of 2022 and 2003.
This is reflected in a report by Ecologists in Action presented this Wednesday at a press conference in Madrid. The work is based on data collected from 493 fixed measurement stations spread across 130 areas and agglomerations. The document includes preliminary data between January 1 and September 30, 2023.
O3 or ‘bad ozone’ usually appears in the months of greatest solar radiation, which is why it is usually linked to spring and summer. It is the atmospheric pollutant that year after year affects more of the population and territory in Spain.
Furthermore, it is a very complex pollutant that does not have a direct human source, but rather It is formed on the Earth’s surface in the presence of solar radiation due to the combination of other pollutants called precursors, emitted by transportation (especially diesel vehicles), thermoelectric plants, certain industrial activities or intensive livestock farming. It is a secondary pollutant that in summer affects suburban and rural areas influenced by urban and industrial pollution.
The report, which is in its eighth annual edition, takes as reference two limit values: the recommendation of the World Health Organization (WHO), which sets the objective at 100 micrograms of ozone per cubic meter of air in periods of eight hours, which must not be exceeded for more than three days a year, and the EU legal objective of 120 micrograms of ozone per cubic meter of air, which must not be exceeded in periods of eight hours for more than 25 days a year.