Exposure assessment


Geographic Information Systems (GIS) will be used to measure environmental exposures, to georeference participants and to integrate clinical and environmental information. Geographic Information Systems are computational systems that allow us to visualize, analyze and interpret geographical data in order to understand relationships, patterns and trends.


To estimate exposure to air pollutants, we will use land-use regression (LUR) models, which are commonly used methods to predict air pollutants’ concentrations at local level whenever the monitoring station network is not dense enough to capture local variability. These models use the measurements of air pollution in a certain location, obtained through stations pertaining to the monitoring network, as response variable and the type of land-use, traffic volume and other geographical characteristics as predictors.


Exposure to greenspaces will be evaluated using local cartography and satellite images that will allow us to calculate the Normalized Difference Vegetation Index (NDVI). This is an important index for studying vegetation, since it allow us to measure, based on satellite imagery, the vitality and characteristics of the vegetation in a certain area. The NDVI is ratio between the difference between near-infrared and visible light and the sum of the two. The NDVI varies between -1 and 1, where values near 1 indicate presence of vegetation and values near -1 indicate the presence of rocks and bare soil.



The information was collected through the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, applied to Geração XXI participants at 4, 7 and 10 years of age. ISAAC is an international study on asthma and childhood allergies and was designed to describe the prevalence and severity of asthma, allergic rhinoconjunctivitis and atopic eczema worldwide. Questions related to asthma, allergic rhinitis and atopic dermatitis are mainly related to the symptoms of each of these pathologies, especially in the last 12 months.

Additionally, we will also consider the results about lung function data which were obtained through spirometry, conducted according to the guidelines of the American Thoracic Society and European Respiratory Society (ATS / ERS). Spirometry, a manoeuvre similar to that of "filling" balloons, allows assessing the volume of air that can be mobilized, either in absolute value or as a function of time (volumes and airway debits).


The project will include the assessment of allergic sensitization in serum samples collected at each Geração XXI evaluation. Allergic sensitization will be measured by ImmunoCAP Phadiatop, in accordance with manufacturer instructions and as commonly used in clinical practice, allowing to assess the real clinical picture of sensitization and to construct age-dependent allergic sensitization profiles.