Understanding the relationship between time spent outdoors, mental well-being and health-related behaviours in a Spanish sample: A real time smartphone-based study

Introduction: COVID-19 pandemic has affected our lifestyle and physical and mental well-being. We aimed to study the effect of being outdoors and mental well-being after the COVID-19 pandemic.Material and methods: We used smartphone based ecological momentary assessments (EMA) (Urban Mind app) to study the mental well-being of the Spanish general population. We collected socio-demographic data, past and current physical and mental health, and social and physical environment. Participants were recruited during 5 months (February to June 2021). Longitudinal associations between EMA and anxiety, depression, loneliness, tiredness, and happiness during the assessments were investigated using random intercept ordinal logistic regression models.Results: 274 subjects downloaded the app and completed the baseline assessment. 66 participants completed at least 50 % of the assessments. Being outdoors was related to a lower likelihood of anxiety (OR: 0.48, 95 %CI 0.34-0.66), depression (OR: 0.40, 95 %CI 0.28-0.56), tiredness (OR: 0.47, 95 %CI 0.35-0.63), and loneliness (OR: 0.59, 95 %CI 0.42-0.84), and a higher likelihood of happiness (OR: 2.14, 95 %CI 1.57-2.93).Conclusions: Being outdoors is related to better mental health in the general population independently of other factors (baseline mental well-being or socio-demographic characteristics). Public policies should include mea-surements to promote outdoor spaces in urban settings.