Science and Innovation

With a degree in environmental sciences and a doctorate specializing in pollution, Anna Gómez joined the Barcelona Public Health Agency in 2007 as a water quality and consumption technician. In 2016, she became head of the Environmental Intervention Service and has been working as head of the Environmental Health Department for just one year (2024).

What jobs does the department include and what does this new position entail?

We focus mainly on environmental monitoring and the impact that different pollutants have on health. In general, it is divided into two different services or areas: one on environmental quality and information and the other on urban pests.

As a more specific job, it motivates me especially, because it is what I wanted to do when I was studying. More than anything because it allows you to put theory into practice, advise and recommend to improve the urban environment, the life of ecosystems, the health of citizens and in the end, also the quality of life.

The good part is this, you can influence the decisions that have to be made. The bad thing is those procedures, in the administrative field, that slow down or hinder progress.

Air quality is directly related to people’s health, and also to the various ecosystems in the environment. How would you rate the evolution of its state in the city?

Progress has been made but more needs to be improved. Progress has always been accompanied by various European directives, which have promoted a minimum framework of action that has reduced pollutants. For example, elements such as lead (previously used in fuels) or also sulfur dioxide (derived from the burning of fuels such as ship fuel) have been reduced to levels that are not of much concern.

All this has been accompanied by the effort to communicate and modernize the entire sampling network and annual reports. Barcelona City Council began analyzing pollutants in the 1960s. But in a more concrete and determined way, everything went much faster with the creation and start of operation, in 2003, of the Barcelona Public Health Agency. Annual reports began to be produced in 2008 and the enabled stations and other sampling tools such as mobile devices were consolidated.

Since 2018, these reports have incorporated levels of impact on health, and also a more accurate description by district (since until then they only differentiated according to the stations).

The 2024 report makes two things clear. We would say as a headline that we are doing better but that we are still a little far from what would be ideal. Do you corroborate these statements?

Without a doubt. To understand it more deeply, it is necessary to consider that there are three reference values. The first, the most permissive, is set by the European standard that is in force (Directive 2008/50/EC) for all pollutants. The second is that of the legislation that restricts all values ​​from the year 2030 (Directive 2024/2881/EC). And the third, and the strictest, is the health protection guide drawn up by the World Health Organization (WHO). Let’s say that now, and it has not always been like this, we at least comply with the law in force. But in some pollutants, those that cause the most effects (such as nitrogen dioxide, the finest particles PM10 or PM2.5 and also ozone) we are above both the WHO guide and what this new directive sets.

Among the compounds analyzed, we focus on these three: NO₂ (nitrogen dioxide), PM 10 (particles between 2.5 and 10 micrometers, µm) and PM 2.5 (particles smaller than 2.5 micrometers). The first is lowering its levels and remains, for the second consecutive year, within the legal values ​​allowed (40 µm/m3 annual average). How is it created, what is its impact and how can it be further reduced?

Nitrogen dioxide arises from the combustion of industries and vehicle engines (as the most prominent sources). But in a special way in the city it is linked to those areas with much more road traffic. It causes adverse effects on health, especially in the respiratory tract, and can also induce lower resistance to infectious diseases. Since 2005 it has had a progressive downward trend and it has only been in recent years (from 2020 onwards) that it has already been within the legal values ​​(below 40 µg/m³ as an annual average). To reduce it obviously and very directly, it is necessary to reduce the volume of cars and motor vehicles circulating in the city

PM 10 and PM 2.5 particles, on the other hand, have a more diverse origin. Where exactly do they come from?

Well, from much more diverse sources. They are designated by their thickness (the aerodynamic diameter) and come from both natural sources (such as sea salt or suspended minerals) and emissions generated in construction sites, industry and other reactions.

These two groups of compounds have remained fairly stable since 2013, but above the levels that would be optimal. Should we be concerned?

Such fine particles, inhaled in the short or long term, cause respiratory and other cardiovascular effects. They also promote lung cancer and can have some adverse effects related to pregnancy. On the other hand, it has been shown that they can have consequences for the neurological development of children and can also be associated with certain chronic diseases such as diabetes.

But these statements are based on different tests and new studies that are updated. Every so often this evidence is reviewed and the values ​​that can cause effects. Those established by the WHO, although low, can have consequences depending on the people, but at least they are considered safer thresholds. What is missing is to see the correlation and the overall effects of concentrating several pollutants in the same point.

To try to reduce them, solutions have been devised such as filters in vehicles, or also in chimneys. They have lowered them a little but they have not done enough, we need to go even further and take structural remedies.

The report also details other pollutants, such as ozone (O₃). Where does it come from and how can we reduce it further?

Ozone arises from reactions in the atmosphere of substances such as nitrogen dioxide (NO₂) or volatile organic compounds (that group of hydrocarbons that have a gaseous state at room temperature). Especially heat (radiation at certain levels) causes changes (breakages) in the molecules and causes the oxygen radicals to converge and end up forming O₃ (Ozone). It is, therefore, a derivative of the entire cluster of substances that surround the city, and is generated, especially in the summer. Contrary to what happens with nitrogen dioxide, it spreads more with the wind and although it has been generated in Barcelona, ​​we often see large concentrations of it in other places such as the Plana de Vic or Cerdanya.

Ozone also causes very harmful effects on health, causing irritation to the eyes, respiratory tract, headaches, decreased lung function, damage to the liver, kidneys and central system. And in the case of plants, it reduces their photosynthetic capacity.

On the other hand, the report includes compounds such as benzene (C6H6), carbon monoxide (CO) or sulfur dioxide (SO2). Should we be concerned about any of them?

Many are still present but in insignificant quantities. None of these exceed the values ​​established by the WHO guideline document. What needs to be investigated further are all those pollutants that are not yet monitored and that are mentioned in the new European standard. For example, the case of black carbon, a product of the incomplete combustion of engines (especially diesel), stoves or wood, which end up forming soot, or finer particles, almost imperceptible, and with a high capacity to penetrate and accumulate in tissues.

We also measure the emissions that may derive from the Port, which we have found to decrease as they move away from their origin. Here nickel serves as a tracer to calibrate its concentration, which is already lower in stations such as Verdaguer or Plaça Universitat. Little by little, more attention and refinement will be needed, especially in the case of black carbon.

How do all these substances affect the health of citizens and the environment?

Well, the figures are very clear. The report estimates that currently the pollutant values ​​have caused in Barcelona (in the period 2020 – 2024) 1.300 deaths each year (8% of all natural deaths), 800 cases of childhood asthma and another 120 annually also of lung cancer. The figures have been reduced compared to the previous period (2018-2019) but could be 38% lower if the thresholds stipulated by the new European standard are met.

For effects, in addition to those already described, all pollution creates cognitive problems, long-term consequences, and even accelerates dementia. It is important to involve the medical sector here and communicate the figures to all citizens so that they can be well aware of them. By now there are already groups that have come together to raise awareness and fight for cleaner air, such as Eixample Respira.

Is the Climate Plan, approved in 2024, the framework for preventing the conditions?

It is a new step forward but now it will have to be complemented with more specific measures. Streets have been pacified, and other measures such as Low Emission Zones have helped reduce the number of vehicles, but there are still many cars. Green space or pedestrian streets help a lot but only near where they are located. We need to expand and make more global the solutions that also include strengthening public transport, urban and interurban, and the freight network. And perhaps also coercive measures, such as more penalties, to reduce traffic levels that are still high on major roads.

In general, air quality has a problem, and it affects many administrations and multiple departments and thus it is difficult to move forward. But we trust that the measures being approved, the work that is progressing here at the city hall and the adoption of the new European law will help accelerate this progress towards a cleaner atmosphere.

How can we make further progress towards cleaner air in the city of Barcelona?

We need to be even stricter and promote a city framework that reduces trips and uses other means of transport such as bicycles. This transformation that many people may see as a stumbling block must be explained positively in order to encourage this change. And to think that a city with much less traffic also means having less noise, fewer accidents, much less stress, less pollution and ultimately a friendlier environment, with many more social ties, cleaner air and better health. That we can is very clear. During COVID-19, NO₂ levels dropped considerably in just a few days. With everyone’s effort, we could get back to that point.