Air pollution has been proven to cause lung cancer and other respiratory diseases, and the U.S. Environmental Protection Agency (EPA) sets regulations and standards to reduce PM2.5 – the specific type of air pollutants that are detrimental to human health. PM2.5 stands for particulate matter less than 2.5 microns in diameter – smaller than 100 times the thickness of a strand of human hair. The standard regulations for PM in the U.S. should be less than 35.5 micrograms PM2.5 per cubic meter according to the EPA. However, the World Health Organization recommends this level should not exceed more than 10 micrograms per cubic meter.
Multiple studies have shown that air pollution results in physical ailments such as asthma, lung cancer and restrictive lung disease. Smog also is linked to cognitive decline and psychiatric morbidity.
Studying the mental effects of smog
A recent study performed in Sweden looked at a national register for prescriptions of 552,000 children and adolescents under the age of 18 and compared them with measured levels of particulate matter concentrations to link potential psychiatric conditions with air pollution. The researchers believe that air pollution may have a direct link to cognitive disabilities such as autism.
“They found that for every 10 micrograms per cubic meter of nitrogen dioxide, the likelihood that children were prescribed medication for at least one psychiatric diagnosis increased by 9 percent,” wrote David Kirby in a TakePart magazine article about the study. “The group of drugs prescribed included antipsychotic medications, sedatives, and sleeping pills.”
In a study at the Ohio State University, researchers devised an experiment in which mice were exposed to high levels of fine particulate air pollutants five times a week. These mice were compared to controls, which were not exposed to high amounts of pollution. The results indicated a high level of cytokines, which are markers of inflammation, in the brains of those mice that were exposed to the pollutants. The researchers also discovered physical changes in brain structure in the hippocampus, an area in the brain dedicated to memory. Specifically, the neuronal connections were decreased, resulting in poorer spatial memory.
Additionally, researchers at Columbia University followed 200 Boston children for the first 10 years of their lives and discovered that those who were exposed to greater amounts of pollutants while in utero had an increased prevalence of anxiety, depression and attention problems.
The young are not the only ones affected by air pollution. Jennifer Weuve, M.P.H., Sc.D., an assistant professor of internal medicine at Rush Medical College, discovered that older women who were exposed to high pollutant levels experienced greater cognitive decline than other women of similar age.
Although there may be confounding factors such as traffic and overcrowding, these confounders are difficult to isolate. Although there is a strong correlation between air pollution and mental health problems, more studies will need to be performed to be able to show a direct link between the two.
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About the author
Kristen Fuller, M.D., is a senior staff writer at Sovereign Health and enjoys writing about evidence-based topics in the cutting-edge world of medicine. She is a physician and author who also teaches, practices medicine in the urgent care setting and contributes to medicine board education. She is also an outdoor and dog enthusiast. For more information and other inquiries about this article, contact the author at firstname.lastname@example.org.