The power of citizen data
The subject of this study was chosen by Barcelona residents themselves during a participatory process that took place in 2019 and involved over 1,000 inhabitants. During the study, nearly 300 volunteers provided information on their habits and mobility over the course of 160 days. They took several tests of attention span and processing speed, answered a series of questions on stress level, quality of sleep and mood via an app, and shared GPS data that made it possible to estimate the time spent in different parts of the city and their exposure to pollutants. They also wore a sampling device to measure the levels of nitrogen dioxide concentration they were exposed to over the course of a week.