Several factors can contribute to depression, but researchers at the University of Bristol have uncovered another possible one: air pollution. A new study suggests that increased exposure to air pollution might be linked to higher rates of depression in the elderly and working-class adults. The team also found that people who live in urban areas where air pollution levels are high are more likely to be depressed than people who live in rural areas with lower levels of air pollution. This could mean that reducing air pollution may improve the mental health of thousands of people across the world every year.
Impacts of air pollution on asthma, allergies
To start, air pollution triggers inflammation of all kinds. This includes allergies, which cause inflammation in your respiratory tract and lungs. Many of these particles also have nitrates in them, which can affect your body’s immune system by increasing asthma attacks and even triggering allergies. Additionally, these tiny pollutants—like asbestos or dust—can enter your body through any little cut or scrape you might have and cause an infection or irritation. When you already suffer from depression, such as postpartum depression or seasonal affective disorder (SAD), it makes things even worse. Think about it: You already feel down because of your symptoms, but then when these pollutants invade your system…well, that just puts you over-the-top depressed!
The link between depressive symptoms and air pollution
Researchers examined 1,151 people in Sydney, Australia. They found that individuals who lived in areas with more than 30 micrograms of particulate matter smaller than 2.5 micrometers per cubic meter were 27 percent more likely to experience depressive symptoms like irritability or fatigue during their commute home compared to other times during two weeks, according to lead study author Andrew G. Bush from the University of Sydney, in Australia. The link was even stronger for those living with asthma or cardiovascular disease.
Previous studies examined the link between depression & heart disease
High levels of air pollution seem to increase the risk of death from heart disease. One study found that suicide attempts and major depression occurred more often in areas with higher air pollution. Another showed that women with high exposure to traffic-related air pollution were more likely to be diagnosed with depression than those who lived in areas with lower pollution. These results, however, were inconsistent between studies, as some found no connection between major depression and levels of ambient PM2.5 (tiny particles, 2.5 micrometers or less in diameter). This study wanted to know if people living in polluted cities have a higher risk for mood disorders like major depression compared to their peers living elsewhere.
How the current study was different
A study, published in 2014, established a correlation between air pollution and depression. In that paper, people with higher levels of exposure to nitrogen dioxide (NO2) were more likely to be depressed. However, it wasn’t clear whether air pollution caused depression or if depressed people simply tended to live in areas with high levels of NO2. The researchers behind that study wanted to see if they could replicate their findings—but test another pollutant as well.
Not only is air pollution bad for people who have heart disease, cancer, or respiratory illnesses—but it can also cause a host of other health problems. According to researchers at Johns Hopkins University in Baltimore, Maryland, a pregnant woman’s exposure to traffic-related air pollution may have an impact on her unborn child’s risk of developing depression later in life. The team studied over 1,000 expectant mothers—half of whom had been diagnosed with depression before or during their pregnancy. Researchers found that those women with a history of depression were 2.6 times more likely to be exposed to higher levels of traffic-related pollutants than women without a history of mental illness. This suggests that there may be a link between maternal exposure to traffic-related air pollution and the subsequent development of depressive symptoms in children. Although these findings are still preliminary, they suggest that pregnant women should take precautions to avoid high levels of air pollution if possible—especially if they suffer from depression.
Researchers from Germany concluded that exposure to air pollution results in a small, but measurable effect on mood – specifically on depression. This doesn’t mean that you should go out of your way to cause yourself depression as a coping mechanism, but it does show how interconnected our health is with other factors around us. If you’re feeling depressed and can’t seem to pin down why, consider looking into any possible environmental causes first – rather than turning to medication immediately.