How Air Pollution May Lead To Rise In Mental Disorders

In this week's article for Breathe Series, Kiran Manral digs into researches and studies which point to correlation between air pollution and rise in mental health issues.

Kiran Manral
Oct 07, 2019 06:45 IST
air pollution mental health

If you thought pollution only affected your physical health, you couldn’t be more mistaken. New research is putting up a strong case for the link between exposure to air pollution and the growing incidence of mental health disorders. This is across age groups.


Scientists at Cincinnati Children's Hospital Medical Center, in collaboration with researchers at the University of Cincinnati have released studies that corroborate the relationship between air pollution and mental health in children.

Researchers at the Cincinnati Children’s Hospital Medical Centre and the University of Cincinnati have found that short term exposure to air pollution worsened psychiatric disorders amongst children, one to two days later. They came to this correlation by measured patient intake at the emergency department of the hospital, for psychiatric disorders over a five year period. Data from 6,800 children was analysed for this. To quote lead study author Cole Brokamp, Ph.D., a researcher in the division of Biostatistics and Epidemiology at Cincinnati Children's Hospital, from a story in Forbes, "This study is the first to show an association between daily outdoor air pollution levels and increased symptoms of psychiatric disorders, like anxiety and suicidality, in children. More research is needed to confirm these findings, but it could lead to new prevention strategies for children experiencing symptoms related to a psychiatric disorder.” Among the findings of the study were that kids from disadvantaged neighbourhoods were more susceptible, specifically to anxiety and suicidal tendencies. To quote Dr. Brokamp, from the same report, “The fact that children living in high poverty neighborhoods experienced greater health effects of air pollution could mean that pollutant and neighborhood stressors can have synergistic effects on psychiatric symptom severity and frequency.”

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Another study established a connection between High traffic-related air pollution exposure and children’s mental health. Researchers used Neuroimaging techniques to trace metabolic disturbances in the brains of children who were exposed to high air pollution caused by traffic. These were kids who were otherwise healthy and found symptoms of generalised anxiety disorders in these kids. They concluded that this could be caused by the brain responding to air pollution.

We must remember that pollution levels in Indian cities are amongst the highest globally. In India, an estimated 140 million people breathe air which is 10 times or more over the safe limit recommended by the World Health Organisation. Of the 20 cities across the world with the highest levels of air pollution, we have the distinction of having 13 in India. And the 2016 Environmental Performance Index ranked India 141 out of 180 countries, a sorry rank to be at. Correlations between physical health, mortality and air pollution have long been established. Reports, including one by the World Health Organization, state than indoor air pollution and carbon monoxide poisoning claim over 300,000 to 400,000 live in India. These are deaths caused by the burning of biomass and the use of chullahs. Reports from the nonprofit organisation Health Effects state that a million Indians die prematurely every year due to air pollution. The Delhi Hearth and Lung institute states that over two million children that are approximately half the children in Delhi could have abnormalities in their lung function

Another study found that exposure to high levels of vehicular pollution caused anxiety and depression amongst 12-year-olds. This study, however, was self-reported so the findings are considered less dependable than other studies, but when taken in tandem with other studies they may prove that air pollution exposure can impact a child’s mental health.


A related study found that early-life exposure to TRAP (Tartrate-resistant acid phosphatase) was associated with higher self-reported anxiety and depression symptoms among 12-year old children. Since these results relied on self-reporting, they are less reliable than those from the other studies, but still, add to an overall evaluation of how air pollution may affect children’s mental health.

"Collectively, these studies contribute to the growing body of evidence that exposure to air pollution during early life and childhood may contribute to depression, anxiety, and other mental health problems in adolescence," said the study co-author Patrick Ryan, PhD.

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The latest studies were published in the journals Environmental Health Perspectives and Environmental Research.

Another study of London-based children from a UK longitudinal cohort study released in Feb 2019 stated, “Exploratory analyses were conducted on 284 London-based children from the Environmental Risk (E-Risk) Longitudinal Twin Study. Exposure to annualized PM2.5 and NO2 concentrations was estimated at address-level when children were aged 12. Symptoms of anxiety, depression, conduct disorder, and attention-deficit hyperactivity disorder were assessed at ages 12 and 18. Psychiatric diagnoses were ascertained from interviews with the participants at age 18. We found no associations between age-12 pollution exposure and concurrent mental health problems. However, age-12 pollution estimates were significantly associated with increased odds of major depressive disorder at age 18, even after controlling for common risk factors. This study demonstrates the potential utility of incorporating high-resolution pollution estimates into large epidemiological cohorts to robustly investigate associations between air pollution and youth mental health.”

Reports from the nonprofit organisation Health Effects state that a million Indians die prematurely every year due to air pollution


The effect of pollution on mental health isn’t limited to children though. A report published on August 20, 2019, found that Environmental pollution is associated with increased risk of psychiatric disorders in the US and Denmark. To quote from the abstract of this study, “We present exploratory analyses of 2 independent, very large datasets: 151 million unique individuals, represented in a United States insurance claims dataset and 1.4 million unique individuals documented in Danish national treatment registers. Environmental Protection Agency (EPA) county-level environmental quality indices (EQIs) in the US and individual-level exposure to air pollution in Denmark were used to assess the association between pollution exposure and the risk of neuropsychiatric disorders. These results show that air pollution is significantly associated with an increased risk of psychiatric disorders. We hypothesize that pollutants affect the human brain via neuroinflammatory pathways that have also been shown to cause depression-like phenotypes in animal studies.”

Scientists in the United States found counties with the worst air quality, as indicated by the Environmental Protection Agency, had a 27 percent increase in bipolar disorder and a 6 percent increase in depression when compared to the national average.

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The US study looked at 11 years of health insurance data for 151 million people who had filed claims for bipolar disorder, major depression, personality disorder, schizophrenia, epilepsy and Parkinson’s disease. The researchers then studied the pollution levels across air, water and land, checking where the insurance claims and intense pollution came from. They found a definite overlap between air pollution and bipolar disorder. The study was replicated the format in Denmark and Danish scientists looked at exposure to air pollution in childhood. They found the exposure to air pollution was associated with higher rates of bipolar disorder and depression.

The link between lowered intelligence and air pollution exposure was defined last year when scientists in Beijing found that inhaling particulate matter from polluted air led to lower scores in language and math. The author of the study, Xin Zhang theorised that the pollution was damaging to the white matter in the brain.

Interestingly, in London, an experiment had 250 students wear backpacks with sensors to monitor air quality on their journey to school and back in order to judge at what points in their journey they were most exposed to pollution.


Taking regular nature breaks could be one way to alleviate the issue. Says Haimanti Pandey, Life Coach and Counsellor who is also researching conditioning and depression, that psychologists often suggest that for a change, parents take kids to places that are open to nature as often as they can, because these are beneficial to a person’s mental health.

According to Dr Megha Consul, Principal Consultant and Neonatologist, Max Speciality Hospital, Gurgaon, pollution can interfere with brain development in children. She states, “Air pollution potentially affects children’s brains through several mechanisms. Particulate matter can cause neuro-inflammation by damaging the blood-brain barrier – a thin, delicate membrane that protects the brain from toxic substances. Particulate matter that is equal or less than 2.5 microns in diameter pose an especially high risk because they can more easily enter the blood stream and travel through the body to the brain. Further, the dosage of toxic chemicals required to damage the growing brain in the first stages of life is much lower than that which would cause damage to an adult brain. Specific air pollution particles, such as magnetite, are so small that they can enter the body through the nose and the gut. Magnetite is very common in urban outdoor air pollution, and a recent study found that it was considerably more present in brains of people living in areas where urban air pollution is high. These nanoparticles are highly toxic to the brain due to their magnetic charge and their ability to help create oxidative stress – which is often the cause of neurodegenerative diseases. Several studies also show that polycyclic aromatic hydrocarbons (PAHs), a specific class of pollutants formed from fossil fuel combustion and commonly found in areas of high automobile traffic, brain containing nerve fibers that are critical in helping nerve cells communicate across different parts of the brain. As children grow and experience the world around them, well-functioning neural connections provide the foundation for continued learning and development.”

Adds Dr Consul, “Participate in movements to pressure governments into taking notice and making policy changes. Advocacy for the environment for our children is something all mothers will have to do in the future!”

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