Some might think that the nexus between air pollution and mental health is nonexistent. It sounds like a reach compared to other systems, after all. In reality, the two are very much connected. Air pollution has a significant and negative impact on various aspects of mental health. In honor of Mental Health Awareness Month and National Mental Health Awareness Week, let’s talk about the relationship between air pollution and mental health. Here’s what recent research and scientific studies have found.
A Large-Scale Air Pollution and Mental Health Study
A recent study involving nearly 14,000 people in London revealed a connection between air pollution and psychotic and mood disorders. Researchers followed patients from their first contact with mental health services. They focused on patients 15 years or older who lived in the cities of Southwark, Lambeth, Lewisham or Croydon at the time. Researchers used high-resolution estimates of air pollution at the patients’ homes to determine their exposure level.
According to the study, a minor increase in exposure to nitrogen dioxide increased the risk of needing community-based mental health treatment by 32% and being admitted to the hospital by 18%. Those who did not experience increased air pollution exposure were less likely to require the aforementioned services.
How Air Pollution Contributes to Mental Illness
After seven years, researchers revisited the data. They found that the connection between air pollution and psychotic and mood disorders remained. They did not design the study to prove causation. However, the connection is “biologically plausible.”
Air pollution is inflammatory. And inflammation is a known factor in psychotic and mood disorders. Previous research has suggested that “air pollutants could affect the brain directly by translocating along the olfactory nerve and permeating the blood-brain barrier and/or indirectly by eliciting systemic inflammation.” In other words, air pollutants take a direct approach and travel along the nerve that allows you to smell. Then they break through the blood-brain barrier. Or, they take a more indirect approach and cause inflammation by forcing the immune system to constantly be on the defense.
How Does Air Pollution Affect Children’s Mental Health?
Dr. Frederica Perera and her colleagues at the Columbia University’s Mailman School of Public Health analyzed the effect of air pollution on children’s mental health. They followed children from New York City while in utero until the age of six or seven. They found that children exposed to higher levels of polycyclic aromatic hydrocarbons in utero were more likely to experience symptoms of anxiety and depression. Essentially, researchers discovered that air pollution exposure is powerful enough to influence children’s mental health before they are even born.
The Institute of Psychiatry, Psychology and Neuroscience at King’s College London and Duke University conducted a joint, 25-year-long study of more than 2,000 children. All of the children were twins, born in England and Wales. When the children turned 18, their mental health was assessed. Children who had the most exposure to nitrogen oxides and particulate matter scored more than two points higher on the general psychopathology score. Researchers discovered that children who grow up with heavy traffic-related air pollution are more likely to experience mental illness. More specifically, exposure to nitrogen oxides and particulate matter is directly related to the development of anxiety and depression.
Does Early Air Pollution Exposure Affect Mental Health Later in Life?
A New Zealand study followed approximately 600 children for more than 30 years. Children that experienced significant exposure to lead also experienced significant psychopathology and difficult personality traits later in life. For example, internalizing and neuroticism were associated with higher childhood blood lead levels.
An American and Danish study found that exposure to air pollution early in life is indicative of mental health later in life. Researchers analyzed an American health insurance database of approximately 150 million people and 11 years of claims, and a Danish dataset of 1.4 million people born between 1979 and 2002. Air pollutants studied included particulate matter, nitrogen dioxide and polycyclic aromatic hydrocarbons among others.
In the United States, researchers found a 27% increase in the rate of bipolar disorder and a 6% increase in the diagnosis of major depression. In Denmark, researchers found a 148% increase in the rate of schizophrenia, a 29% increase in the rate of bipolar disorder, a 162% increase in the rate of personality disorder, and an approximately 50% increase in the rate of major depression.
Clean Air Benefits Mental Health
It is evident that air pollution and mental health are related. While there are various uncontrollable factors that contribute to poor mental health, air pollution is not one of them. There are a number of steps we can take to decrease their production of and exposure to air pollution. Clean air is a human right, and we must do all that we can to protect that right. Especially when it positively and negatively influences our mental health.