Air Quality and Mental Health: The Global Environmental Crisis Reaches Inward
New Delhi, India, has some of the worst air pollution in the world. In the winter of 2022, the fine particle concentrations in the city’s atmosphere hit three times the recommended levels.
Both the immediate and long-term impacts of environmental issues on physical health are widely recognized throughout the scientific community and, increasingly, the general public. However, the natural environment also influences us in more subtle ways that can be difficult to detect through physical senses alone. Emerging research suggests, for example, that declining air quality—a global trend—may be linked to poor mental health.
It makes sense when one thinks about it; fine particles of polluted air can enter the bloodstream along with the oxygen molecules the brain demands in significant quantities every minute. Thus, the environmental state in which one lives is a determining factor in more than one’s physical state. According to a study published in the United Kingdom in the summer of 2023, there is evidence that unclean air is associated with generally reduced mental health for potentially as long as the entire “life course,” as well as with specific mental disorders, which tend to be more severe and possibly just as enduring.
In a 2018 study conducted in Indonesia several decades after a series of devastating wildfires that polluted the atmosphere with smoke, researchers aimed to explore this potential long-term relationship. It was found that participants of both sexes tended to experience intensified depressive symptoms—as compared to those previously present—if they had been especially exposed to the effects of the fires. Women were more likely to experience clinical depression than men, while those with greater wealth and higher education experienced reported less severe impacts in general.
The scale of air pollution’s impact on global mental well-being, perhaps easily underestimated due to its intangible nature, may be huge. According to the World Health Organization, 99 percent of the global population face health risks from both indoor and outdoor air pollution; a recent 2023 review of more than 100 studies focusing on the impacts of air pollution on emotion-regulating brain regions found that nearly 75 percent of total participants—including both humans and non-human animals—experienced “higher mental health symptoms and behavior…after exposure to higher-than average levels of air pollution”.
Globally, it is estimated that air pollution contributes to one in every ten deaths. Industrialized countries tend to be significant contributors to declining air quality, yet poorer nations bear a disproportionate share of the consequences. Air pollution-related death rates are greatest in low-income and mid-income countries, particularly in Africa and Southeast Asia. While the rate of indoor air pollution deaths, caused by the burning of solid fuel like wood or peat, has dropped significantly since the 1990s, the rate of deaths due to outdoor air pollution,the result of a much longer-term, larger-scale environmental crisis, has seen only moderate improvement.
Amid these concerns, some countries offer hopeful examples. As of March 2024, seven countries—Australia, Estonia, Finland, Grenada, Iceland, Mauritius, and New Zealand—meet the World Health Organization’s guidelines. While these seven represent a fraction of the 134 countries analyzed (the other 127 fell short of the WHO’s standards), they provide a model for other nations striving to improve air quality and, in turn, protect both physical and mental health.