Cognitive Performance and Stress Worsen on High-Pollution Days in Barcelona

Cognitive performance and stress worsen on high-pollution days in Barcelona. These are the preliminary results of CitieS-Health, a European citizen-science study coordinated by Ideas for Change and the Barcelona Institute for Global Health (ISGlobal)—a centre supported by the ”la Caixa” Foundation—with the goal of measuring how pollution affects the mental health of people in the city. The study took place over several months, with the voluntary participation of nearly 300 residents, who enabled the researchers to collect information on habits and mobility over the course of 160 days.

Research has shown that people have greater difficulty concentrating on the days when air pollution is highest. Specifically, reaction time and cognitive performance can drop by about 5% on a high-pollution day compared to a day with clean air. On days with higher levels of pollution, stress levels also increase by roughly 0.5 (on a scale of 0-10) compared to a clear day. The study also found that, on high-pollution days, the cognitive health of people living close to a green or blue space (such as the sea) is less affected than that of people living farther away, whereas the relationship between air pollution and cognitive well-being does not seem to vary with noise exposure. The findings of the study are currently being written up in a scientific article for validation via the peer-review process.

Citizen Data and Public Data Support the Findings

The analysis conducted by the CitieS-Health team used citizen data provided by study participants. For two non-consecutive weeks, participants took a test of attention span and processing speed and answered a series of questions on stress level, mood and sleep quality via an app. In many cases, participants also provided their GPS mobility data to estimate the correspondence between pollutant concentration and time spent in different parts of the city. In addition, more than 260 volunteers wore apassive sampling device to measure the accumulated NO _₂ concentration they were exposed to over the course of a week.

To compare the sample and establish correlations, the results were cross-checked against public data such as the average pollutant concentrations collected by the stations in Barcelona’s Air Pollution Monitoring and Forecasting Network, as well as the city’s strategic municipal noise map and land-use maps.

Citizen Proposals to Be Presented at Park(ing) Day 2021

The public’s interest in the effects of pollution on mental health was evident throughout the project. In fact, Barcelona residents themselves chose the subject of analysis for this study. In 2019, a participatory process involving more than 1,000 inhabitants of Barcelona found that mental health was the issue that generated the most interest.

The results of the study are just the first step towards remedying the situation. At the online presentation of the research findings, four dialogue sessions were held with city residents. With the support of local communities that are active in promoting citizen science and sustainable habits in the city, participants discussed ideas for actions that could be implemented by private citizens and public bodies alike to help address important issues.

The areas identified for exploration were art and greening to counteract pollution and its effects on mental health (in collaboration with Enverdim), sustainable mobility to improve health and quality of life (with contributions from WeCount), how our data can contribute to future health research (with the support of Salus Coop) and healthy habits to foster emotional well-being and mental health (coordinated by #PaulaDivulga).

The citizen recommendations will be presented on 17 September as a part of Park(ing) Day Barcelona 2021—a community-driven intervention to reclaim public space—and shared with the relevant government bodies to raise awareness. A stand set up at Carrer Padilla 230 will host an interactive and participatory visualisation of the study’s findings, the steps followed during the experiment, the final conclusions and a compilation of citizen actions to combat air pollution and improve mental health.