Short-term NO2 exposure and cognitive and mental health: A panel study based on a citizen science project in Barcelona, Spain

Background: The association between short-term exposure to air pollution and cognitive and mental health has not been thoroughly investigated so far. Objectives: We conducted a panel study co-designed with citizens to assess whether air pollution can affect attention, perceived stress, mood and sleep quality. Methods: From September 2020 to March 2021, we followed 288 adults (mean age = 37.9 years; standard deviation = 12.1 years) for 14 days in Barcelona, Spain. Two tasks were self-administered daily through a mobile application: the Stroop color-word test to assess attention performance and a set of 0-to-10 rating scale questions to evaluate perceived stress, well-being, energy and sleep quality. From the Stroop test, three outcomes related to selective attention were calculated and z-score-transformed: response time, cognitive throughput and inhibitory control. Air pollution was assessed using the mean nitrogen dioxide (NO2) concentrations (mean of all Barcelona monitoring stations or using location data) 12 and 24 h before the tasks were completed. We applied linear regression with random effects by participant to estimate intra-individual associations, controlling for day of the week and time-varying factors such as alcohol consumption and physical activity. Results: Based on 2,457 repeated attention test performances, an increase of 30 mu g/m(3) exposure to NO2 12 h was associated with lower cognitive throughput (beta =-0.08, 95% CI:-0.15,-0.01) and higher response time (beta = 0.07, 95% CI: 0.01, 0.14) (increase inattentiveness). Moreover, an increase of 30 mu g/m(3) exposure to NO2 12 h was associated with higher self-perceived stress (beta = 0.44, 95% CI: 0.13, 0.77). We did not find statistically significant associations with inhibitory control and subjective well-being. Conclusions: Our findings suggest that short-term exposure to air pollution could have adverse effects on attention performance and perceived stress in adults.