Anatomy of a historical haze: this is how the particle concentration records were pulverized

The Saharan dust intrusion episode that much of the Peninsula and the Balearic Islands have experienced this week, with the strongest peaks on Tuesday and Wednesday, has been truly extraordinary due to its intensity and geographical extension.

This is confirmed by the data from the air quality control network of the Ministry for Ecological Transition: in 107 of the 471 stations in Spain that measure the presence of PM₁₀ particles (those with a diameter of less than 10 microns) they have been detected. daily concentrations never before recorded.

In other words, this extreme phenomenon has led to record records in 23% of the country's stations, according to the analysis carried out by EL PAÍS of these data.

The Saharan dust has fully impacted the Peninsula and has left a trail of historical marks in Andalusia, Murcia, the Valencian Community, Castilla-La Mancha, Madrid, Castilla y León, the Basque Country, Cantabria, Asturias and Galicia.

But the crown is taken by a station in Almería: in El Ejido an average concentration of 1,779 micrograms per cubic meter (µg/m³) was recorded on March 15.

To understand what this means, it is useful to know that the World Health Organization (WHO) set an average daily exposure of 45 μg/m³ as a safety limit in its latest air quality guide.

On Tuesday in El Ejido the concentration of particles was almost 40 times higher.

This is the highest concentration collected in any of the 471 stations with which the ministry works and whose measurements go back in some cases, such as El Ejido,

"Here, not even the oldest remember anything like it," says Pilar Bellido, a pharmacist from Almeria who lives in Aguadulce and works in El Ejido.

And that in Almería these episodes are not extraordinary.

"We are used to haze that lasts two hours, four hours, but never this, and in winter," she says.

"It's like a very dense fog, but orange, it looks like the apocalypse," she says about the worst episode of haze that she has experienced in her 65 years.

If in El Ejido that average concentration of 1,779 micrograms per cubic meter was reached, in the nearest neighboring station —located in Almería capital and called Mediterráneo— the team did not give more of itself on Tuesday and, when it reached a concentration of around than 1,000 micrograms, he did not measure further.

"Several stations have collapsed in this episode," explains Sara Basart, a researcher at the Barcelona Supercomputing Center–National Supercomputing Center.

The historical marks were not limited only to Almería or Murcia.

As the Saharan dust cloud advanced — “there are studies that indicate that the dust moves at about 50 kilometers per hour,” Basart points out —, the measurement stations along the way saw the concentrations of dust skyrocket. PM₁₀, as occurred for example in Villanueva del Arzobispo (Jaén), where 1,000 μg/m³ were exceeded.

This station began to accumulate data on these particles in 2004. And the highest daily average that the ministry has registered in Villanueva del Arzobispo dated January 2007;

and they were 268 micrograms, four times less than now.

The WHO, in its latest guide on pollution, points out that Saharan dust intrusions are one of the factors that contribute to worsening air quality.

And he warns: "There is a close quantitative correlation between exposure to high concentrations of particulate matter and increased daily and long-term mortality or morbidity."

In Spain there are studies that relate the increase in hospital admissions and this type of haze episodes.

It is still early to draw health conclusions about the phenomenon experienced in Spain this March and that is still active, but in some provinces they are already offering data.

In Almería, according to the Junta de Andalucía, until this Thursday, 250 people had been treated in hospital emergencies for ailments related to the calima.

Paradoxically, at the Hospital de Poniente de El Ejido there has been no explosion of cases: between Monday and Thursday morning 24 patients had attended as a result of the haze, explains a spokeswoman for the center.

"They are patients with previous respiratory conditions (asthma or COPD) who, after consultation, adjustment of treatment and useful recommendations, have not required admission," she adds.

There have also been cases of mild eye and skin conditions.

For Miguel Angel Baena,

During Tuesday and Wednesday, the Saharan dust penetrated deeper and deeper into the Peninsula, to the point that all PM₁₀ particle measurement stations in Castilla-La Mancha, the Community of Madrid and Castilla y León exceeded 100 micrograms, more than twice what is recommended by the WHO.

In those of Madrid, they comfortably exceeded 300 and even 400.

And, further to the northwest, the situation did not improve: at the Ávila measurement station, for example, 861 μg/m³ were reached, undoubtedly the highest mark recorded in the decade that this facility has been operating.

This meter is among the 10 in the country that have marked a higher concentration during this phenomenon, according to data provided by the ministry.

"This has been an exceptional episode for the Iberian Peninsula, especially in the southeast, where the data is historical," says a "surprised" Carlos Pérez García-Pando in a preliminary analysis of the figures provided by the European Environment Agency. , also from the Barcelona Supercomputing Center–National Supercomputing Center.

"In mainland Spain, the years 2021 and 2022 have seen two very strong entries of dust in suspension, although last year's was not as extensive, since it affected the east and the Pyrenees," adds García-Pando.

The network of stations that Spain has, and which report to the European Environment Agency, serves to monitor the quality of the air in the country and so that the European Commission can also monitor it.

Currently, European regulations establish a daily average concentration limit of 50 μg/m³.

But, to be considered an infraction, that value must be exceeded 35 days a year.

In addition, according to Marta Muñoz Cuesta, deputy director of Clean Air and Industrial Sustainability at the ministry, Saharan dust intrusions do not count when Brussels analyzes non-compliance with pollution regulations.

At the moment, the Ministry for the Ecological Transition is finalizing the approval of a royal decree in which, among other things, the thresholds for exceeding contaminating particles will be set, points out Ismael Aznar, general director of Quality and Environmental Evaluation.

This will serve so that local administrations can alert the population when episodes of this type are detected so that they can take measures, such as reducing outdoor sports or, as has happened with this extreme haze, wearing masks.

In addition, Aznar recalls that his ministry has just launched a new digital viewer that not only allows air quality to be checked in real time at the country's network of measurement stations, but also to access the forecast for the next few hours to take precautions .

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