Annual Congress 2022 of the European Academy of Allergy and Clinical Immunology

(Prague, Czech Republic, 1-3 July 2022) The world is rapidly urbanizing with significant changes in lifestyles, behaviours, and health. This growing urbanization is also associated with increased exposure to air pollution, loss of natural environments and biodiversity. Furthermore, this everchanging urban environment has an impact on disease patterns and prevalence, namely on noncommunicable diseases, such as asthma and allergy, and poses many challenges to understand the relationship between the changing on the urban environment and human health.

The dynamic interaction between host and its microbial community in an environmental context, as proposed by the holobiont concept, respond and change to environmental exposures. However, the loss of natural spaces and biodiversity, also associated with growing urbanization, may leads to a reduced or to an imbalance in human microbiota, immune dysfunction and inflammation, and to a higher risk of inflammatory diseases, such as allergy and asthma.

Several studies have assessed the association between exposure to natural spaces, including green and blue spaces, and the development of allergic diseases and asthma, however the results are inconsistent. The heterogeneity of results may be related to geographic location, season, moment of exposure and outcome assessment, but also to the definitions and conceptualization (availability, accessibility, or visibility) of exposure to green and blue spaces. Results from a study using seven birth cohorts from five countries showed contrasting associations between green spaces and allergic diseases among children. Recent studies also showed that lifetime exposure to green spaces and exposure at specific time points over the life course were protective against allergy, asthma, and lung function, suggesting that the timing of exposure may be critical and pertinent in understanding health effects.

There is also evidence showing that high exposure to green spaces in school and residential neighborhoods was associated with a lower prevalence of asthma and allergic symptoms in a dose-response manner, suggesting a healthy dose of exposure to green spaces. Furthermore, a growing body of evidence suggests that living near blue space may have positive effects on physical and mental health by lowering the levels of environmental hazards and increased physical activity and social connection. And how about the effect of exposure to blue spaces on asthma and allergy? Inconclusive and no significant associations were observed between the exposure to blue space asthma, allergic diseases and lung function. Several mechanisms have
been proposed to explain the health effects of natural spaces. Exposure to natural spaces may affect the composition of the human microbiota, exposure to air pollution and pollen concentrations, and the autonomic nervous system activity, which in turn may reflect immunologic responses to environment and protect against allergy and asthma.

“Therefore, growing urbanization, the related increasing air pollution levels, loss of green spaces and biodiversity, and changes in lifestyle raise new challenges, but also offer opportunities to better understand the pathways linking natural environments to human health and to increase connectivity between ecosystems providing more livable and healthier cities, protecting human health. Most of the studies provide evidence that natural spaces and biodiversity may be a protective factor for the development of allergy and asthma, showing that integrating natural elements into cities in a controlled way and promoting the contact of
humans with nature may be an effective strategy to promote human health as well as prevent allergic and respiratory diseases,” says Inês Paciência, Center for Environmental and Respiratory Health Research, Oulu, Finland, at the opening plenary symposium of the EAACI Annual Congress 2022 in Prague.

About EAACI

The European Academy of Allergy and Clinical Immunology (EAACI) is an association of clinicians,
researchers and allied health professionals founded in 1956. EAACI is dedicated to improving the
health of people affected by allergic diseases. With more than 13 000 members from 125
countries and over 75 National Allergy Societies, EAACI is the primary source of expertise in
Europe and worldwide for all aspects of allergy.

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