Children who study in schools with a higher number of trees in the surrounding areas have lower levels of exhaled nitric oxide, a marker that is used to assess airway inflammation. The conclusion is from a study by the Instituto de Saúde Pública da Universidade do Porto (ISPUP), published in the European Annals of Allergy and Clinical Immunology.
The investigation, which follows a previous article that found a benefit of green spaces for children’s lung function, analyzed whether the density and type of trees existing around schools affected the inflammation of children’s airways, which is associated with symptoms such as difficulty in breathing, dry cough and wheezing.
To carry out the study, the authors evaluated the number and type of trees that were located within a distance of 500 meters from 20 primary schools in the city of Porto, which agreed to participate in the study. The presence of coniferous trees, such as pines, and broadleaf trees, such as plantains, were considered.
The researchers also assessed lung function and the level of airway inflammation in a sample of 845 children who were attending these educational institutions. The nitric oxide exhaled by children was used as the marker to assess airway inflammation.
The importance of nitric oxide
Nitric oxide “is formed in our body and consists of a response of the inflammatory process to an external factor. In areas with greater pollution, there is an increase in the inflammatory response, and, consequently, a greater production of nitric oxide by the body”, indicates Inês Paciência, first author of the study, coordinated by André Moreira.
The research concluded that children who study in schools with a higher density of broadleaf or coniferous trees in the surrounding areas exhale smaller amounts of nitric oxide, which means that they have a lower inflammatory response in the airways.
As Inês Paciência explains, “broadleaf or coniferous tree can help to reduce the pollution present in the air, either by serving as a barrier to pollutants, or by absorbing some pollutants themselves, thus contributing to reduce pollution in areas around schools”. For this reason, “the nitric oxide levels exhaled by children are lower”.
The authors point out that the beneficial effects of the presence of trees near schools are not only felt among children with asthma, but also in healthy children.
“We observed that both asthmatic and non-asthmatic children had a reduction in airway inflammation, and that the former also showed a reduction in the symptoms associated with asthma”, she says.
The importance of a green city
For the researcher, the study entitled Association between the density and type of trees around urban schools and exhaled nitric oxide levels in schoolchildren, accessible HERE, demonstrates that proximity to green spaces is associated with better health.
“It is important to have a green city that promotes the improvement of air quality, because it has an impact on the quality of life and health of the population. In terms of urbanism, it is crucial to think about the types of trees that we put around buildings and how they can help to reduce pollution”.
The researchers João Rufo, Ana Isabel Ribeiro, Francisca Castro Mendes, Mariana Farraia, Diana Silva and Luís Delgado also participated in the article.