Cognitive performance and stress worsen during the most polluted days in Barcelona

Cognitive performance and stress worsen during the most polluted days in Barcelona. This is the main conclusion of CitieS-Health, a European citizen science study coordinated by Ideas for Change and the Barcelona Institute for Global Health (ISGlobal), a centre promoted by "la Caixa" Foundation, to measure how pollution affects the mental health of people in the city. The analysis was carried out over several months thanks to the commitment of almost 300 residents, who took part in the research on a voluntary basis, enabling information on habits and mobility to be collected over a total of 160 days.

The research has revealed that citizens show a lower level of concentration during the days when air pollution is at its highest. In particular, reaction time and cognitive performance can vary by about 5% between a clean day and a day with high air pollution. Stress levels also increase on days with higher levels of pollution. The difference is 0.5 (on a scale of 0-10) between a highly polluted day and a clear day for this indicator. In parallel, the study has revealed that, during the most polluted days, the cognitive health of people living close to a green or blue space (such as the sea) is less affected than that of those living far away, while the relationships between air pollution and cognitive well-being do not seem to vary according to noise exposure. A scientific paper with the results is currently being drafted for validation through a peer-review process.

To conduct the analysis, the CitieS-Health team relied on citizen data provided by participants in the experiment. For two non-consecutive weeks, they took a test of attention span and processing speed and a series of questions about stress level, mood and sleep quality via an app. In many cases, they also provided their mobility data (GPS) to estimate the correspondence between pollutant concentration and time spent in different areas of the city. In addition, more than 260 volunteers carried a small tube for passive NO₂ collection, which made it possible to measure the cumulative concentration of this pollutant accumulated by each participant over the course of a week.

In order to compare the sample and establish correlations, the results were cross-referenced with other public data such as the average concentration of pollutants collected by the stations of the Barcelona City Council's Air Pollution Monitoring and Forecasting Network, the strategic municipal noise map of Barcelona and the city's land use maps.

In order to compare the sample and establish correlations, the results were cross-referenced with other public data such as the average concentration of pollutants collected by the stations of the Barcelona City Council's Air Pollution Monitoring and Forecasting Network, the strategic municipal noise map of Barcelona and the city's land use maps.

Citizens' interest in the impact of pollution on mental health has been reflected throughout the project. Not surprisingly, it was the residents of Barcelona themselves who chose the subject of analysis for the study. In 2019, a participatory process was carried out involving more than 1,000 Barcelona residents in which mental health was the most voted issue.

The results of the study are just the first step towards reversing the situation. During the event to present the findings of the research, organised virtually, four dialogue tables were set up with residents of the city. With the support of local communities active in promoting citizen science and sustainable habits in the city, participants discussed ideas for actions that can be implemented by both private individuals and public administration and that contribute to addressing the problems detected.

The areas of exploration are: art and green interventions to counteract pollution and its effects on mental health (driven with the collaboration of Enverdim), sustainable mobility to improve health and quality of life (with the contribution of WeCount), how our data can contribute to future scientific research in health (with the support of Salus.coop), and healthy habits to contribute to emotional well-being and mental health (coordinated by #PaulaDivulga).

The recommendations compiled by citizens will be presented at Park(ing) Day Barcelona 2021, the citizen intervention to reclaim public space scheduled for 17 September this year, and will be shared with the relevant public administrations to raise awareness. The stand, located at Carrer Padilla 230, will host an interactive and participatory visualisation of the results of the study, showing the steps followed during the course of the experiment, the final conclusions and a compilation of citizen actions to combat air pollution and improve mental health.