Research found that those who grow up amid heavy traffic pollution have higher rates of mental illness by age 18

Children and young people who grow up amid heavy traffic-related air pollution have higher rates of mental illness by the time they are 18, new research has found.

There is a link between exposure to nitrogen oxides and particulate matter in childhood and the development of disorders such as anxiety and depression, the academics said.

The findings are from a 25-year-long joint British/American study of 2,039 children – all twins – born in England and Wales during 1994 and 1995, whose mental health was assessed at 18.

“These results collectively suggest that youths persistently exposed to moderate levels of nitrogen oxide air pollution may experience greater overall liability to psychiatric illness by young adulthood”, the authors concluded.

The link between air pollution and risk of mental illness is “modest” but real, they added. The association was also “a liability independent of other individual, family and neighbourhood influences on mental health”, such as poverty and family history of mental disorder.

Dr Helen Fisher, the study’s co-author, said: “This study has demonstrated that children growing up in our biggest cities face a greater risk of mental illness due to higher levels of traffic.

“While we might like to think of our towns and cities as green and open spaces, it’s clear that there is a hidden danger that many will not have even considered.”

Fisher was the principal investigator of the study at the Institute of Psychiatry, Psychology and Neuroscience at King’s College London, which also involved Duke University in the US.

Participants’ mental health was measured when they were 18 using an assessment of symptoms for ten common psychiatric disorders, such as ADHD, anxiety and alcohol dependence. That was used to calculate a measure of their mental health called the psychopathology factor or p-factor. Those with a higher p-factor score displayed more of those symptoms.

The researchers found that those who had the highest exposure to nitrogen oxides scored 2.62 points higher on the general psychopathology score than their peers in the bottom three quartiles. Those exposed to the most particulate matter scored 2.04 points more than their peers.

Andy Bell, deputy chief executive of the Centre for Mental Health thinktank, said: “We know from research that our mental health is determined by the lives we lead, the environments we’re in and our experiences from our early years onwards. A child’s mental health is influenced by many factors, including their home, school, community and neighbourhood.

“We know that poverty, racism, trauma and exclusion are major risks to mental health. As today’s research shows, our physical environment matters too, and making places safer, cleaner and healthier to live in will have lifelong benefits.”

Pollution has already been identified as an aggravating factor for poor heart and lung health and ailments of the central nervous system, and also as a risk for mental illness. Nine out of ten people worldwide are exposed to high levels of pollution, according to the World Health Organization.

Kevin McConway, emeritus professor of applied statistics at the Open University, said that while the study did show an association between traffic fumes and mental ill-heath, “what they can’t do is to show that it’s the high air pollution that actually causes the poorer mental health.”

Study links childhood air pollution exposure to poorer mental health | Air pollution | The Guardian