According to a new study on the effects of urban air pollution on mental health, increases in people’s exposure to air pollution are associated with significant rises in anxiety and depression.
The study shows that a gradual increase in nitrogen dioxide (NO2), mainly produced by diesel vehicles, amplifies the risk of common mental disorders by 39%. While tiny particle pollution (also called PM), mostly from burning fossil fuels and tire dust, causes the risk to rise by 18%.
People living in places with higher PM levels were found twice as likely to experience mental health issues than those living in the least polluted areas. However, the researchers acknowledged that other factors are a significant cause of mental health, such as childhood experiences or genetics. Regardless, unlike these factors, air pollution could be prevented.
Over five years, the study followed over 1,000 adults in the London borough of Southwark and Lambeth, but the results are applicable for cities globally. In the UK, almost all urban areas have PM levels over the WHO guidelines, while 90% of people worldwide breathe dirty air.
Dr. Ioannis Bakolis, a lecturer from King’s College London who led the study, explained:
Air pollution is not the only factor that may have an impact on the presence of mental disorders, but it is a preventable one. Introducing measures to reduce air pollution may represent a rare and potentially impactful primary health measure for the prevention of psychiatric disorders.
According to Dr. Ian Mudway, a member of the research team and a lecturer at Imperial College London, mental health disorder rates are higher in urban areas, with suggested causes including deprivation of green spaces. “The amazing thing with this study is that when you control all of those other features of the urban environment and socioeconomic factors, the air pollution signal remains. It’s a very robust finding,” he said.
Dr. Mudway added:
There is now an increasing body of evidence suggesting air pollution isn’t great for the brain either. We may actually have been underplaying the adverse effects of air pollution on our health from cradle to grave.
The research, published in the journal Social Psychiatry and Psychiatric Epidemiology, used standard questionnaires to evaluate the subjects’ mental health for more than five years. It used data on individuals to consider age, frequency of smoking, drinking, exercise, socioeconomic status, and neighborhood deprivation.
The results showed average NO2 levels in the boroughs varied between 24 and 83 micrograms per cubic meter, and a rise in the exposure of only three units increased the risk of mental disorders by 39%. PM ranged from 9 to 23 micrograms per cubic meter, with a 5-unit rise leading to an increased risk of mental health conditions by 18%.
Anna Hansell, a professor at the University of Leicester, thought the research was fascinating and carefully conducted, but more studies are needed to confirm their findings. “However, there are already urgent grounds to reduce air pollution due to its association with chronic disease and premature deaths,” she added.
Hansell advises people to regularly exercise, as it’s incredibly beneficial to physical and mental health. Even in polluted areas, people can find a less polluted route for walking, running, or riding a bicycle. They can also exercise inside their homes, such as jump roping, push-ups, squats, or yoga.
