Tropospheric ozone, a particularly complex pollutant and the most widespread in Spain, has continued its decline since the pandemic began. Since the beginning of the year, 1.4 million Spaniards have breathed air with dangerous levels of this gas – taking into account the limits allowed by the European Union – a figure far removed from the 9.6 million before the pandemic and even three million less than last year, when the confinement was decreed. If you take the much stricter scales set by the World Health Organization (WHO), the scenario turns black: people exposed to that unhealthy air skyrocket to 34.6 million, 73% of the population, which is which also represents a drop of between two and seven million people compared to years prior to the virus. Tropospheric ozone is a powerful oxidant that causes lung conditions, aggravates asthma, increases mortality in chronic patients, and causes headaches and fatigue, among other adverse health effects.

The decline “has had an influence on the fact that there have continued to be traffic restrictions and there has been less industrial activity, in addition to the fact that the summer was less hot than other years,” explains Miguel Ángel Ceballos, from Ecologistas en Acción. Ozone appears in spring and summer because to form it needs solar radiation, along with other pollutants that are called precursors and that are emitted by automobiles (nitrogen dioxide is the main one), large thermoelectric plants, industrial activities or intensive livestock. With this background, it is not surprising that its levels have fallen in a scenario with mobility restrictions due to the virus, which shows the connection between the production of this gas and polluting emissions. What conservationists did not expect is that once the COVID containment measures were lifted, the ozone would be further reduced.

There have continued to be exceedances of the threshold in which citizens must be informed, but they have remained at fifty, and it has only risen above the alert limit in Tarragona. It is the lowest figure since “there are systematic records of this pollutant, in the early 1990s,” says the ecologists’ report. The most affected territories are distributed in the Community of Madrid, the interior of Catalonia and the Valencian Community, the city of Cáceres and the industrial area of ​​Puente Nuevo, north of Córdoba. Ozone has another peculiarity. It is not a static gas. It occurs in the areas where the substances that originate it are emitted, but then it moves and affects more virulence in suburban and rural areas downwind of large urban agglomerations.

Ecologists in Action warns that to date there are very few territories that have protocols for action against these ozone peaks, and only the Valladolid City Council “contemplates and applies traffic limitation measures” at that time. A dozen autonomous communities (Andalusia, Aragon, the Balearic Islands, Castilla-La Mancha, Castilla y León, Catalonia, Valencia, Madrid, Murcia, Navarra and the Basque Country) still do not draw up air quality improvement plans, despite being mandatory. The Ministry for Ecological Transition has also not prepared the National Plan for Tropospheric Ozone, in which many regional governments hide to undertake the reforms that they have pending, warn conservationists.

There is only one way to stop the pollutant: reducing traffic, improving rail transport or saving and energy efficiency, among other measures, says the NGO. In addition, it is necessary to expand the available scientific information on gas dynamics, although this circumstance “cannot serve as a political alibi for not acting.”

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