Depression affects more than 19 million Americans each year, according to Mental Health America. With that being said, a new study done by Jama Network has revealed exposure to air pollution has certain associations with depression, specifically for people above the age of 64.

Published on Feb. 10, 2023, four departments in Harvard’s T.H. Chan School of Public Health looked into 1,526,690 patients diagnosed with depression and observed similar long-term exposure to air pollutants between individuals. The participants were all enrolled in the Fee-for-Service program and both Medicare Part A and Part B. 56.8% of individuals were female and 90.2% were white and the average age was 73.7. The exposure that was measured was to fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃) through a tripollutant model.

There have been several previous studies that have suggested air pollution translocates to the central nervous system through nasal epithelial and alveolar capillary dysfunction and blood-brain barrier breakdown, eliciting adverse neuroinflammatory and autoimmune responses. This process could potentially cause increased levels of oxidative stress in the brain and trigger more stress hormones to be released. More stress hormones have been associated with outcomes like mental illnesses, including depression. As older generations have weaker immune systems, they become more susceptible to the pulmonary and neural impacts air pollution causes as it accumulates, and are then heavily impacted by air pollution.

As 9 out of 10 people find themselves inhaling air pollution long-term, the rising generations are notably becoming more at risk for illnesses like depression. And, as expensive medical care in the United States continues on, the costs for people will become yet another obstacle.

Combating air pollution is not an easy feat, especially in countries with a high level of carbon dioxide and particle matter emissions. Linked to the individual, vehicle emissions can have a major impact on the planet, which is why public transportation or other forms of transport like biking or walking are highly encouraged, as they incorporate fewer emissions collectively. Other than vehicles, byproducts from manufacturing and power plants cause the majority of air pollution, often being ozone, which also worsens global warming.

Exposure to air pollution is fairly unavoidable, especially in urban areas or in areas with a lot of vehicles in the area. In European countries like the Netherlands, air pollution is significantly less and the overall population is found to be less impacted by it as they incorporate more public transportation and encourage walking. Though it’s difficult to change the lifestyle of over 300 million people, it does start with the individual. Carpooling and using public transportation is environmentally friendly and can help save money in the long term as well.