The Effects of Air Pollution on Brain Activity

By: Jackie Dutkanych

According to the World Health Organization, there are 4.2 million deaths worldwide caused by air pollution. More than 90 percent of the world’s population is breathing in unhealthy air on a daily basis. We often hear about how human pollution is affecting Earth, causing climate change and global warming, and how this will affect the next generation. New studies, detailed below, show that the quality of air you breathe in is not only affecting your lungs and respiratory system, but is now affecting your brain function. 

Air pollution refers to the amount of harmful particles in the atmosphere, usually expressed in parts per million (PPM). In the atmosphere, there are harmful substances called particulate matter. Fine particulate matter are very small particles that linger in the air. They are so small that they are less than the width of a strand of human hair, making these particles easy to unknowingly inhale while almost invisible to the human eye. Nonetheless, when these participles build up, this is what creates the atmosphere to appear hazy. This matter is often referred to as PM2.5. PM2.5 contains a mixture of soil, dust, acid like nitrates and sulfates, and metals toxic to humans. These metal-toting particles damage neutrons in the brain. PM2.5 comes directly into the atmosphere through emissions from trucks, construction sites, unpaved roads, fires, and emissions from crude oil plants, power plants, industrial buildings and automobiles. 

Deborah Slechta, principal investigator at University of Rochester Medical Center, was originally researching how lead exposure may affect children when she made a startling new discovery. She conducted a controlled experiment that exposed mice to various levels of air pollution, with some levels similar to what parts of the human population breathe in everyday. Slechta monitored the mice’s behavior patterns and activity before and after exposure. Then, examined the mice’s brains through a series of MRIs and EEGs. Magnetic resonance imaging (MRI) is a non-invasive body and brain imaging system that uses strong magnetic fields and radio waves to produce images showing the inside of organs. An electroencephalogram (EEG) is another non-invasive test that measures the amount of activity in the brain to detect any abnormalities in the way the brain functions. 

Slechta said that at first, “[she] didn’t think air pollution [was] a big problem for the brain.” After performing and reviewing the MRIs and EEGs from the mice exposed to poor quality air, she said “It was eye-opening. [She] couldn’t find a brain region that didn’t have some kind of inflammation.” Slechta’s team studied the mice’s brains to explore whether there were any unusual brain movements or patterns. Her team continued the research and found that mice that were exposed to air pollution shortly after birth soon showed clear signs of behavioral issues. These signs developed into characteristics that resembled neurological problems like autism, attention-deficit disorder and schizophrenia. 

Slechta’s team found connections between short term air pollution exposure and impaired cognitive abilities. They placed the non-exposed mice and the exposed mice into mazes to navigate, where the researchers detected changes in both behaviors and activity. The exposed mice showed issues of short-term memory loss associated with object recognition. They also showed spontaneous behavioral movements and high-activity tendencies. 

The World Health Organization reported in 2018 that nine out of ten people globally breathe in poor quality air with unsafe levels of PM2.5.

“The health effects of air pollution are all about particle size,” says Deborah Slechta.

These particles are inhaled through the nose and mouth, and then get transported to the brain via the bloodstream. However, recent studies have shown that it’s possible for these particulates to bypass the bloodstream altogether and go directly to the brain via the olfactory nerve (NCBI, 2018). With the human population at a new all-time high for constant exposure to pollution, how will we be able to protect our brains?

Cover photo courtesy of Pixabay

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