EXALAR XXI is a project of the Public Health Institute (ISPUP) and Faculty of Medicine from Porto University that will study the association between urban environment and allergic diseases and asthma among children using knowledge from geography, biology, medicine and environmental sciences.

Currently more than 150 million Europeans suffer from allergic diseases and estimates suggest that by 2025 half of the European population will be affected.

This public health problem is particularly burdensome among pediatric populations. Allergic diseases and asthma, in particular, are one of the most common chronic non-communicable diseases among children, being the first cause of hospitalization in children from high income countries.

Urbanisation and urbanisation-related detrimental exposures – air pollution, heat stress, poor and unequal access to natural and biodiverse spaces – have been indicated as possible culprits for such remarkable increase in allergic diseases and asthma.

The ‘biodiversity hypothesis' defends precisely that reduced contact with natural environments and biodiversity in the first years of life may disrupt the development of immune function, causing susceptibility to allergens and abnormal immune responses to common epitopes later in life. Yet, scientific evidence about this possible association remains inconclusive.


Therefore, the EXALAR XXI project will investigate how the exposure to urban pollution, green and blue spaces, and biodiversity influence the development of allergic diseases and asthma in children.

To reach this objective, this project will be grounded on data from the Geração XXI (G21), a population-based birth cohort established in 2005/6 comprising 8647 newborns from Porto Metropolitan Area. Since then, these children have been regularly evaluated to collect detailed clinical, social, demographic and biological data, which can be used to address important scientific questions.

Additionally, EXALAR XXI it will be also anchored on mixed data sources that will allow a deep characterization of the biogeophysical exposures (pollution, green and blue space and biodiversity) across Porto Metropolitan Area.

The integration of the two information (clinical and environmental) will be possible because all participants from the cohort are georeferenced, thereby allowing matching participants to places and the tracking of cumulative and spatially varying environmental exposures.

With EXALAR XXI, we aims to address the scientific questions around which the project was built, but we do also expect to answer to real-life practical problems and to produce recommendations that could be used be decision makers and urban planners towards the creation of healthy, inclusive and sustainable urban environments.