Children with greater proximity to green spaces have less asthma and allergic diseases

A study by the Instituto de Saúde Pública da Universidade do Porto (ISPUP) showed that green spaces protect against the development of asthma and allergic diseases in childhood.

The research, published in the journal Allergy, found that children who, since birth, live in areas closer to green spaces, have less allergic rhinitis and asthma, at 7 years of age. The study also observed that exposure, from early ages, to a high number of animal species does not have the same protective effect.

Several previously published studies have shown contradictory results regarding the influence of green spaces in the development of allergic diseases and asthma. There are articles that demonstrate a protective effect while others consider that exposure to these spaces is a risk factor.

In order to clarify the issue, ISPUP researchers sought to assess the effect of early exposure to green areas on the development of allergic diseases and asthma in children, using a sample of 1050 children from the Municipality of Porto, belonging to the longitudinal cohort study Generation XXI.

The environment around children’s homes was analyzed, considering the existing green spaces and their proximity to the homes of the participants in the study.

Additionally, the species richness index (which indicates the number of different animal species present in a given space) in the green areas, near the children’s homes, was considered. The objective was to understand whether contact with a greater richness of species could also have a protective effect against the development of the diseases mentioned, something that “had never been studied until now”, indicates João Rufo, first author of the research, coordinated by Ana Isabel Ribeiro.

Through the application of questionnaires to the participants, the researchers analyzed if, at 4 and 7 years of age, the children already had a history of allergic diseases and asthma.

The study found that…

Children from the Municipality of Porto who were closer to green spaces, since birth, had fewer allergic diseases, namely allergic rhinitis, and asthma, at 7 years of age. According to João Rufo, this result “corroborates articles that observed the protective effect of green areas and demonstrates that being in contact with vegetation in urban areas is beneficial for health”.

However, and contrary to the expected, a greater proximity to species richness was not protective, having even been considered to be a risk factor. In fact, children who had a closer contact with a high number of species had a greater allergic sensitization and, among those who already had asthma and wheezing, it was found to aggravate these pathologies.

One of the possible explanations for this result may be related to the release of molecules (allergens) by animal species, which in turn cause allergic reactions in the human body. This may exacerbate symptoms of allergy and asthma that have already been diagnosed. However, further studies on this topic are needed, given that, “contrary to what we found in these children from the Municipality of Porto, there are articles that show a beneficial effect of exposure to a greater richness of species”, notes Rufo.

Public health message

The published study showed “that green spaces are beneficial for health and that they can help prevent the occurrence of asthma and allergic diseases, such as rhinitis, in children”, underlines the researcher.

Thus, it is important to enhance its use among the youngest individuals and also pregnant women, since the perinatal period (which includes the pregnancy period until 2 years of age) is crucial for the prevention of these pathologies, which represent a high cost to the National Health Service.

Allergic rhinitis is one of the most common allergic diseases among the Portuguese population and, in the Northern Region of Portugal, the prevalence of asthma varies between 6 and 9%.

The Exalar XXI project

The article entitled The neighborhood natural environment is associated with asthma in children: a birth cohort study was developed within the Exalar XXI project, which aims to study the association between urban environment and allergic diseases and asthma among children using knowledge from geography, biology, medicine and environmental sciences.

The ISPUP article is available HERE. The researchers Inês Paciência, Elaine Hoffimann, André Moreira and Henrique Barros also participated in the study.

Image: Unsplash/Krisztina Papp 

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