Depressed? Anxious? Air pollution may be a factor
In the 1990s, residents of Mexico City noticed their dogs acting strangely — some didn’t recognize their owners, and the animals’ sleep patterns changed.
At the time, the city of more than 15 million people was known as the most polluted in the world, with a thick, constant haze of fossil fuel pollution trapped by thermal inversions.
In 2002, toxicologist and neuropathologist Lilian Calderón-Garcidueñas, who is affiliated with both Universidad del Valle de México in Mexico City and the University of Montana, examined brain tissue from 40 dogs that lived in the city and 40 others from a nearby rural area with cleaner air. She discovered the brains of the city dogs showed signs of neurodegeneration while the rural dogs had far healthier brains.
Calderón-Garcidueñas went on to study the brains of 203 human residents of Mexico City, only one of which did not show signs of neurodegeneration. That led to the conclusion that chronic exposure to air pollution can negatively affect people’s olfactory systems at a young age and may make them more susceptible to neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
The pollutant that plays the “big role” is particulate matter, Calderón-Garcidueñas said. “Not the big ones, but the tiny ones that can cross barriers. We can detect nanoparticles inside neurons, inside glial cells, inside epithelial cells. We also see things that shouldn’t be there at all — titanium, iron and copper.”
Calderón-Garcidueñas’ work is feeding a burgeoning body of evidence that shows breathing polluted air not only causes heart and lung damage but also neurodegeneration and mental health problems.
It’s well established that air pollution takes a serious toll on the human body, affecting almost every organ. Asthma, cardiovascular disease, cancer, premature death and stroke are among a long list of problems that can be caused by exposure to air pollution, which, according to the World Health Organization, sits atop the list of health threats globally, causing 7 million deaths a year. Children and infants are especially susceptible.
Some psychotherapists report seeing patients with symptoms stemming from air pollution. Not only does the pollution appear to cause symptoms or make them worse, it also takes away forms of relief.
“If we exercise and spend time in nature, we become extra resilient,” said Kristen Greenwald, an environmental social worker and adjunct professor at the University of Denver. “A lot of folks do that outside. That’s their coping mechanism; it’s soothing to the nervous system.”
On polluted days a lot of her clients “can’t go outside without feeling they are making themselves more sick or distressed.”
Oona Tempest, KFF Health News Illustration
A digital illustration in watercolor and pencil shows a human with a melancholy expression, their head encircled by air pollution that billows up from surrounding smoke stacks. The background depicts a city at night.
Megan Herting, who researches air pollution’s impact on the brain at the University of Southern California, said environmental factors should be incorporated in doctors’ assessments these days, especially in places like Southern California and Colorado’s Front Range, where high levels of air pollution are a chronic problem.
“When I go into a medical clinic, they rarely ask me where I live and what is my home environment like,” she said. “Where are we living, what we are exposed to, is important in thinking about prevention and treatment.”
In the last two decades, with new technologies, research on air pollution and its impact on the human nervous system has grown by leaps and bounds.
Research shows tiny particles bypass the body’s filtering systems as they are breathed in through the nose and mouth and travel directly into the brain. Fine and ultrafine particles, which come from diesel exhaust, soot, dust and wildfire smoke, among other sources, often contain metals that hitchhike a ride, worsening their impact.
A changing climate is likely to exacerbate the effects of air pollution on the brain and mental health. Warmer temperatures react with tailpipe emissions from cars to create more ozone than is generated when it’s cooler. More and larger forest fires are expected to mean more days of smoky skies.
Ozone has been linked to neurodegeneration, decline in cerebral plasticity, the death of neurons, and learning and memory impairment.
Air pollution also causes damage from chronic inflammation. As air pollution particles enter the brain, they are mistaken for germs and attacked by microglia, a component of the brain’s immune system, and they stay activated.
“Your body doesn’t like to be exposed to air pollution and it produces an inflammatory response,” Patrick Ryan, a researcher at Cincinnati Children’s Hospital, said in an email. “Your brain doesn’t like it either. There’s more than 10 years of toxicological science and epidemiologic studies that show air pollution causes neuro-inflammation.”
Damage to the brain is especially pernicious because it is the master control panel for the body, and pollution damage can cause a range of neuropsychiatric disorders. A primary focus of research these days is how pollution-caused damage affects areas of the brain that regulate emotions. The amygdala, for example, governs the processing of fearful experiences, and its impairment can cause anxiety and depression. In one recent review, 95% of studies looking at both physical and functional changes to areas of the brain that regulate emotion showed an impact from air pollution.
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Depressed? Anxious? Air pollution may be a factorCanva
Fine particulate air pollution, or PM2.5, is one of the largest environmental causes of human mortality. PM2.5 exposure is responsible for more than 100,000 premature deaths annually, with Black and Hispanic populations dying at a greater rate than other races.
When inhaled, PM2.5 pollutants—just a fraction of the width of a single strand of human hair—can travel deep into the lung tissue, enter the bloodstream, and increase the risk of cardiovascular disease, respiratory illnesses, and even lung cancer.
Most air pollution can be traced to the burning of fossil fuels, such as gasoline, diesel, oil, and wood. Inhalable particle pollutants form when chemical compounds emitted from industrial sites, automobiles, and other sources undergo chemical reactions in the atmosphere.
Despite average PM2.5 exposure falling 40% nationally over roughly the last two decades, disparities in exposure to this harmful air pollution persist among populations of color and low-income communities. People of color are exposed to more pollution from nearly every source, including industrial, agricultural, vehicular, construction, and residential sources.
New research from the University of California, Berkeley, and the University of Washington proves these present-day disparities are largely rooted in a discriminatory housing practice called redlining. Some neighborhoods—often those populated by people of color or where an industrial site was already located—were given the worst investment risk grades (D) by the federal Home Owners' Loan Corporation. People in D-grade neighborhoods were ineligible for federally backed loans or favorable mortgages and, as a result, could not build wealth through homeownership.
Without the resources and political influence to resist, these neighborhoods became common targets for hazardous waste, as well as industrial facilities and transportation infrastructure built adjacent to or directly through them. More than 80 years later, these redlined communities have consistently higher levels of nitrogen dioxide, a gas found in vehicular exhaust and industrial emissions, and PM 2.5 pollution.
Using data published in the Science Advances journal and gathered for the Environmental Defense Fund, Stacker looked at disparities in particulate pollution exposure in the U.S.
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CanvaFine particulate air pollution, or PM2.5, is one of the largest environmental causes of human mortality. PM2.5 exposure is responsible for more than 100,000 premature deaths annually, with Black and Hispanic populations dying at a greater rate than other races.
When inhaled, PM2.5 pollutants—just a fraction of the width of a single strand of human hair—can travel deep into the lung tissue, enter the bloodstream, and increase the risk of cardiovascular disease, respiratory illnesses, and even lung cancer.
Most air pollution can be traced to the burning of fossil fuels, such as gasoline, diesel, oil, and wood. Inhalable particle pollutants form when chemical compounds emitted from industrial sites, automobiles, and other sources undergo chemical reactions in the atmosphere.
Despite average PM2.5 exposure falling 40% nationally over roughly the last two decades, disparities in exposure to this harmful air pollution persist among populations of color and low-income communities. People of color are exposed to more pollution from nearly every source, including industrial, agricultural, vehicular, construction, and residential sources.
New research from the University of California, Berkeley, and the University of Washington proves these present-day disparities are largely rooted in a discriminatory housing practice called redlining. Some neighborhoods—often those populated by people of color or where an industrial site was already located—were given the worst investment risk grades (D) by the federal Home Owners' Loan Corporation. People in D-grade neighborhoods were ineligible for federally backed loans or favorable mortgages and, as a result, could not build wealth through homeownership.
Without the resources and political influence to resist, these neighborhoods became common targets for hazardous waste, as well as industrial facilities and transportation infrastructure built adjacent to or directly through them. More than 80 years later, these redlined communities have consistently higher levels of nitrogen dioxide, a gas found in vehicular exhaust and industrial emissions, and PM 2.5 pollution.
Using data published in the Science Advances journal and gathered for the Environmental Defense Fund, Stacker looked at disparities in particulate pollution exposure in the U.S.
You may also like: Where US military aid is being spent, ranked
