In Spain, Most of the urban air pollution monitors are not where they should be.This is the conclusion of a comprehensive analysis by Ecologists in Action, which has once again focused on a thorny issue: the way in which pollution levels are officially measured in cities.
According to this work, Three out of four traffic-oriented air quality stations are poorly locatedThe problem is not technical or related to the sensors themselves, but rather to where they are placed: too often far from the busiest streets or at heights and distances that artificially reduce the detected concentrations.
A report that uncovers a structural problem in Spanish cities
The study, entitled 'Traffic and urban air quality in the Spanish State', Check the location of 25 official stations in 25 citiesIt includes the 17 large urban agglomerations with more than 250.000 inhabitants and several medium-sized cities, with at least one urban center analyzed per autonomous community.
For each city, a choice has been made the most representative station for traffic pollution, often the one that records the worst data in the network: points such as Plaza Elíptica in Madrid, Eixample in Barcelona or Olivereta in Valencia are some examples of reference meters in previous analyses.
The work focuses on two scales of analysis: the so-called macro-implementation (the general urban environment where the station is located) and microimplantation (the immediate conditions of the sampling point)It is not enough to be in a polluted city; you have to be on the right street and at the correct distance from the roadway.
The authors examine elements such as type of environment (urban, suburban or rural), proximity to emission sources, road characteristics, land use, building morphology, physical obstacles and dispersion conditions of the pollutants. The general conclusion is clear: in most cases, what is measured does not accurately reflect what people are breathing.
Of the total number of stations evaluated, 19 out of 25, that is, 76%, present partial or total non-compliance of the location criteria set by the new European regulations. Only a minority are considered truly suitable to represent the population's actual exposure to traffic pollution.
The new European directive toughens the rules of the game
The report is published at a key moment, in the midst of the rollout of the European Directive 2024/2881 on ambient air quality and a cleaner atmosphere in EuropeThis regulation, which Spain must transpose into its legislation before the end of the year, significantly strengthens the requirements regarding where and how the meters should be located.
The directive specifies that Sampling points intended to protect human health must provide reliable data in locations with the highest concentrations, and preferably in sensitive areas such as residential zones, schools, hospitals, residences, and office areas.
When the objective is to assess pollution from road traffic, the requirements are even more specific: The stations should be placed on streets with the highest density of vehicles.Taking into account the volume of traffic, the shape of the street and the arrangement of the buildings, including the well-known "urban gorges" or "canyons" where the air is less well renewed.
Furthermore, the regulations stipulate that Each zone must have at least one station at a critical pollution point that measures key traffic-related pollutants: nitrogen dioxide (NO2), particulate matter (PM10 and PM2,5), benzene, and carbon monoxide (CO). If only one sampling point is established in an area, it must be located in that critical area.
European regulation also defines the maximum distance to the edge of the roadway (less than 10 meters) and height of the sampling points (in the typical range of human respiration, below four meters)These conditions are intended to prevent the meters from being too far from the exhaust pipes and, therefore, from registering artificially low levels.
Controversial relocations and a landmark European ruling
Ecologists in Action emphasizes that The location of the measuring stations is one of the most controversial points in air quality management. in Spain and other European Union countries. It's not a new debate: it has been generating tensions between administrations and social organizations for years.
For much of this century, Many autonomous communities and municipalities relocated the “most problematic” stationsGenerally, traffic incidents, from busy roads to secondary streets or urban areas, sometimes following local incidents such as the crisis over Petronor emissions in MuskizThe official argument has often been the need to "comply with legal criteria," but the practical effect has been to lower the recorded pollution figures.
This type of maneuver led to a key precedent in 2019This occurred when the Court of Justice of the European Union issued a ruling on the Brussels air quality monitoring network case. The ruling openly questioned the design of that network and made it clear that cities cannot "hide" pollution by moving sensors away from areas with the worst air quality.
On that basis, the new 2024 directive has been drawn up, which explicitly tightens the location criteria and insists that the data must be representative of the population's actual exposure. The Ecologists in Action report relies precisely on these updated European criteria to assess the situation of monitoring stations in Spain.
According to the environmental organization, This is not just a technical debateIf the monitoring stations are not properly positioned, it is impossible to know precisely when and where the limit values or thresholds recommended by the World Health Organization are exceeded. And without this diagnosis, public policies against pollution are fundamentally flawed.
Macro-implementation: cities without well-measured traffic hotspots
One of the main conclusions of the study is that In several large urban areas, the stations analyzed are not located on streets with the highest concentrations of pollutants.In other words, they fail at the macro-level implementation, in the overall choice of location within the city.
En Barcelona, Bilbao, Elche, Granada, Santander and ValladolidThe traffic monitoring stations examined are not located on streets where the highest pollution peaks are expected. From the perspective of the new directive, they cannot be considered critical pointsTherefore, they do not represent the reality of the areas with the most exposure to traffic.
In other cities, the problem is even more basic: Badajoz, Guadalajara and Logroño do not even have a specific traffic stationIn these cases, the only station selected is located in a Residential urban setting with moderate traffic and distance from the main traffic axes, as happens on Atienza Street in Guadalajara.
The environmental organization maintains that Without a station on a major traffic axis, it is impossible to properly assess the impact of traffic in air quality. Demand it. new measuring points on the main urban roads of these cities, which allow us to know the real pollution to which their inhabitants are exposed in places where there are more cars.
In territories such as EuskadiThe criticisms are repeated. Ekologistak Martxan, linked to the same demands, denounces that the urban meters of Bilbao, San Sebastián and Vitoria-Gasteiz They are also not well located: either because of their distance from traffic or because They are located at such high altitudes that they do not reflect what the citizens breathe..
Micro-implantation: excessive heights and sensors too far from the roadway
Beyond the choice of street, the report identifies a particularly worrying set of problems in the microimplantationThat is, in the exact physical conditions of the location of each station.
Among the most serious deficiencies appear disproportionate sampling heights. In BilbaoOne of the traffic stations is located more than seven meters high, above the normal range for human breathing, while in Las Palmas de Gran Canaria – City Life, History & Island Vibes The meter has been placed on the roof of a market, far above street level.
These cases are in addition to numerous violations of the maximum distance to the edge of the roadwayThe study cites examples in A Coruña, Alicante, Badajoz, Elx/Elche, Logroño, Madrid, Málaga, Donostia/San Sebastián, Vigo and Vitoria-Gasteiz, where the stations are more than ten meters from the busiest tracks, violating the limit set by the directive.
These differences in height and distance are not minor details: A few meters can significantly reduce the recorded concentration of pollutantsIf the sensor is too far from the emission source, the measured levels tend to be much lower than those experienced by pedestrians, cyclists, or residents at street level.
In cities like MurciaThe San Basilio station is located near a major road such as the Ronda Oeste, but The exact location is too far from the roadway According to the new criteria. Ecologists in Action are also calling for a review of other stations in Murcia, such as those in Alcantarilla and Ronda Sur, to bring them into compliance with EU regulations.
The six cities that are spared (with nuances)
Not everything on the map is negative. The report identifies six cities whose analyzed traffic stations mostly comply with the macro-implementation and micro-implementation requirements set by the European directive.
These are the stations located in Gijón/Xixón, Palma, Pamplona/Iruña, Seville, València and Zaragoza. In these cases, The meters are located on streets with high traffic density., at an appropriate distance from the roadway and at heights that reasonably represent the actual exposure of the population.
In the specific case of Gijón/Xixón, for example, the station located in the Constitution Avenue It is considered correctly positioned to measure traffic-related pollution. However, even here, the environmental organization points out that The remaining stations in the local network should be reviewed to ensure that at least half of the checkpoints are located in critical locations.
The same applies to the other "compliant" cities: Its reference stations pass the test, but the entire network still needs adjustmentsThe goal is to avoid having a single well-located station surrounded by poorly installed meters that lower the overall average.
In the opinion of Ecologists in Action, These six cities demonstrate that it is possible to design measurement networks in accordance with European criteriaBut they also highlight that there is still a long way to go to achieve a homogeneous and reliable system throughout the State.
Effects on public health and urban policies
The consequence of this network of bad locations is direct: Official pollution data may not reflect the actual exposure of millions of peopleIf the meters do not capture the maximum levels, agencies and administrations could be assessing air quality with an incomplete picture.
This affects both the activation of anti-pollution protocols and traffic restrictions as the planning of low emission zones or sustainable mobility measures. A city that apparently complies with legal limits could, in reality, be exceeding them on several of its busiest avenues without this being recorded in official records.
The environmental organization itself points out that Air pollution is associated with tens of thousands of premature deaths each year in Europe.respiratory and cardiovascular problems that scientific evidence has clearly linked to continued exposure to NO2 and fine particles.
If the sensors reduce that exposure due to being poorly positioned, There is a risk of minimizing a major public health problem.And, incidentally, it makes it more difficult for citizens to have "clear, accurate and rigorous" information about the air they breathe, as the organization insistently demands.
That is why Ecologists in Action insists that The location of the meters is as important as the technology of the stations themselves.A highly advanced sensor placed in the wrong location can provide very accurate data… but of little use for protecting health.
What Ecologists in Action demands: deadlines, technical guide and participation
Given this diagnosis, the organization puts forward a series of proposals that It is directly linked to the process of transposing the European directive. to the Spanish legal system. The idea is that the new regulations will not remain just empty words, but will translate into visible changes on the ground.
First, the Government is asked to Set a maximum period of one year to review and, if necessary, relocate urban traffic stationsThat timeline should start counting as soon as the state regulation incorporating the European requirements is approved.
The organization also asks that it be guaranteed in each urban agglomeration at least one station located at a critical point of air pollution linked to traffic. This would reduce the risk of exceedances of limit values going undetected due to poorly designed monitoring networks.
Another key claim relates to the development of a state technical guideThe guide, overseen by the Ministry for Ecological Transition and the Demographic Challenge, would ensure that all relevant authorities apply the same macro and micro implementation criteria, preventing lax or disparate interpretations across different regions.
Ecologists in Action also proposes that The redesign of the measurement networks should be supported by atmospheric modeling tools and indicative measurements. that allow for a transparent justification of the selection of critical points. And it proposes that the process of reviewing the location of the stations include mechanisms for citizen participationso that neighborhood associations and social entities can make contributions regarding the most relevant sources of pollution in each municipality.
Meanwhile, local organizations like Ekologistak Martxan or the Ecologists in Action groups in specific cities are moving specific recommendations to regional governments and municipalities, requesting the review of specific stations and the installation of new meters on particularly problematic routes.
The picture painted by this set of reports and analyses is that an urban measurement network that, in much of Spain, is not yet aligned with what Europe requires or with what public health needsThere are examples of cities that have done their homework and have well-located stations, but the majority of cases involve sensors that are too far from traffic, too high up, or simply outside of critical areas. How the review is handled in the coming months will determine whether official data begins to more accurately reflect the air quality on the streets.
