The air quality in the grove and its surroundings remained “good” 97% of the time, compared to the records of the measuring stations of Granada Norte (37%) and the Palacio de Congresos (26%).

“Poplar in Granada is a strategic crop against pollution and should receive public aid,” says Antolino Gallego, coordinator of the LIFE Wood for the Future project, promoter of the study.

Granada, January 8, 2025

A research carried out in the framework of the European project LIFE Wood for Future/Madera para el Futuro, led by the University of Granada (UGR), has shown the protective role of poplar trees against polluting gases and particles, mainly from road traffic and heating boilers, as well as their ability to cushion the negative effects of Saharan dust intrusions.

Enrique Pérez Sánchez-Cañete, professor of Applied Physics at the UGR, installed an air quality measurement station, on loan from the Diputación de Granada, in collaboration with researcher María Ángeles Ripoll, inside the poplar grove of the Instituto de Investigación y Formación Agraria y Pesquera (Ifapa) of the Junta de Andalucía -located in the Camino de Purchil, on the edge of the city-, and compared its results with the records of the stations of Granada Norte and the Palacio de Congresos, between June 10 and July 17, 2022.

The air analysis recorded the presence of urban pollutant gases such as sulfur dioxide, nitrogen dioxide, carbon monoxide and ozone, and coarse (PM10) and fine (PM2.5) suspended particulate matter (PM2.5).

The poplar tree measuring station recorded an Air Quality Index (AQI) considered ‘good’ 97.5% of that period, compared to the records of the other two stations, Granada Norte and Palacio de Congresos, where air quality was ‘good’ 37.3% and 26.6% of the time, respectively; ‘reasonably good’ 50.2% and 61.6%; ‘fair’ 12.4% and 11.7%; and ‘unfavorable’ 0.1% and 0%.

A ‘good’ AQI indicates that air quality is satisfactory and air pollution poses little or no risk to human health and ‘reasonably good’ implies that it may have negative effects for a small group of people – for example, ozone-sensitive individuals – while a ‘fair’ AQI carries risks for people with respiratory and cardiovascular diseases, children and the elder.

The study shows that the poplar tree not only maintains a mostly good air quality, but also acts as a buffer against specific pollution events, such as the intrusion of Saharan dust,” said Enrique Pérez Sánchez-Cañete. It also highlights the importance of implementing nature-based strategies, such as tree planting, to combat the effects of air pollution in and around cities.”

“An important aspect to highlight is that no significant differences were found between the data obtained inside the poplar grove and 50 meters away, suggesting that the positive effect of vegetation on air quality extends beyond the area studied. This highlights the crucial role of poplar groves and vegetation in general as elements capable of mitigating the effects of pollution in urban and peri-urban areas. The ability of plants to filter particles and absorb gaseous pollutants contributes significantly to improving air quality and protecting human health,” concluded the professor.

Granada, due to its climatic and orographic particularities, has been one of the Spanish cities with the worst environmental pollution records for several years, despite its medium size and lack of an important industrial fabric. For Enrique Pérez, the progressive loss of 75% of the poplar groves in the Vega de Granada since the beginning of this century – from 12,000 hectares to 3,000 hectares – is one of the factors that could explain the drastic worsening of air quality in the capital of Granada.

 

More diseases and deaths

Aurora Bueno, professor of Preventive Medicine and Public Health at the UGR, has assured that, although the population is not always aware of it, environmental pollution has direct negative effects on health and, in fact, “is responsible for a third of premature mortality”. “At best, these pollution levels are associated with asthma problems or other respiratory conditions. However, constant exposure to polluted air causes a chronic inflammatory state, associated with multiple chronic diseases and deaths from cardiovascular pathologies and cancer.” As an example, he recalled that after peaks of atmospheric pollution there is a clear increase in heart attacks and cardiovascular accidents.

“We complain about the situation of the health system, the lack of doctors and nurses, but the real problem is the lack of investment in environmental policies that improve the quality of the air we breathe. The presence of trees is one of the key factors for this and Granada, one of the cities with the worst air quality in Spain, has a ratio of meters of green areas per inhabitant far below the recommended figures. Recovering the poplar groves of the Vega is a measure that can help defend us against this invisible enemy that undermines our health and that of our children,” insisted Aurora Bueno.

Other benefits of poplar

Enrique Pérez recalled that, due to their rapid growth – they can reach a height of 20 meters in ten years – poplars have a great capacity to sequester CO2 from the atmosphere, up to 20 tons per year, that is, 30 times more than the herbaceous crops that have been replaced in the Vega of Granada. In addition, poplar trees act as natural vaporizers, as they increase the humidity of the air and lower the temperature by 3 to 6 degrees in summer, and are excellent water pollution filters: in the Vega de Granada they are traditionally irrigated with poorly treated urban wastewater, which recharges the aquifers, improves soil fertility and prevents flooding. Finally, these crops help prevent soil erosion and attract a high biodiversity.

The coordinator of LIFE Wood for the Future, Antolino Gallego, has stressed that the benefits of poplar trees for the environment “should be reflected in the ‘green policies’ of the Junta de Andalucía and the Diputación de Granada for the fight against air pollution and the impact on human health in the Granada metropolis”.

“Poplar is a crop connected with the culture of Granada for 150 years and should receive agri-environmental aid to be economically competitive with other crops in expansion, such as hyper-intensive olive groves in the Vega. It is a strategic crop to fight against air pollution and administrations can not look the other way,” said the professor of Applied Physics at the UGR.

The LIFE Wood for Future project

LIFE Wood for Future/Madera para el Futuro, which has obtained funding from the LIFE Program of the European Union [LIFE 20 CCA/ES/001656] for the environment and climate action, is integrated by the University of Granada, the Provincial Council, the Confederation of Organizations of Foresters of Spain, the University of Santiago de Compostela and the spinoff 3edata.

The project, in addition to promoting the recovery of the poplar groves of Granada with the constitution of the Marjal group, which brings together a hundred producers, promotes the creation of a wood processing industry and research into new materials for sustainable industrialized construction through the spin-off IberoLam Timber&Technology.