Now we finally know why so many city dwellers are depressed — and no, it’s not because of your failing local sports teams.
A new study from King’s College of London found that even tiny increases in vehicle emissions in highly polluted neighborhoods were correlated with shockingly high rates of clinical depression among residents — even when the researchers controlled for common environmental contributors to mental health conditions, like lack of access to mood-boosting green space or substandard housing.
Though all the regions the researchers studied had high rates of vehicle-related pollution, people who lived in neighborhoods that had just 3 micrograms of nitrogen dioxide more per cubic meter had a stunning 39 percent higher risk of a depression diagnosis, when compared with the residents of neighborhoods with the lowest levels of NO2, which is commonly found in diesel exhaust emitted by heavy trucks.
Purpose The World Health Organisation (WHO) recently ranked air pollution as the major environmental cause of premature death. However, the significant potential health and societal costs of poor mental health in relation to air quality are not represented in the WHO report due to limited evidence. We aimed to test the hypothesis that long-term exposure to air pollution is associated with poor mental health.
Methods A prospective longitudinal population-based mental health survey was conducted of 1698 adults living in 1075 households in South East London, from 2008 to 2013. High-resolution quarterly average air pollution concentrations of nitrogen dioxide (NO2) and oxides (NOx), ozone (O3), particulate matter with an aerodynamic diameter < 10 μm (PM10) and < 2.5 μm (PM2.5) were linked to the home addresses of the study participants. Associations with mental health were analysed with the use of multilevel generalised linear models, after adjusting for large number of confounders, including the individuals’ socioeconomic position and exposure to road-traffic noise.
Results We found robust evidence for interquartile range increases in PM2.5, NOx and NO2 to be associated with 18–39% increased odds of common mental disorders, 19–30% increased odds of poor physical symptoms and 33% of psychotic experiences only for PM10. These longitudinal associations were more pronounced in the subset of non-movers for NO2 and NOx.
Conclusions The findings suggest that traffic-related air pollution is adversely affecting mental health. Whilst causation cannot be proved, this work suggests substantial morbidity from mental disorders could be avoided with improved air quality.
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Did they adjust for ability to access medical care?
Study: https://link.springer.com/article/10.1007/s00127-020-01966-x
Okay so it’s a survey not just based on diagnosis statistics. This is also just a correlation but it’s a very reasonably-studied one in this case.