The chance of having a stroke may rise when exposed to air pollution.

September 28, 2023 – Within five days of being exposed to air pollution, there is a thirty percent increase in the risk of stroke, according to recent studies. 110 observational studies from around the globe that recorded the time of strokes and the amounts of common air pollutants five days after a stroke were examined by researchers.The journal Neurology reported the meta-analysis's findings. The effects of air pollution on human health go beyond respiratory and ocular conditions. The University of Jordan's Ahmad Tubasi, the lead researcher, stated on NBC News that "it also involves the brain and cardiovascular system."More than 18 million cases of ischemic stroke—the most frequent kind of stroke, which is brought on by a blood clot that travels to the brain—were included in the meta-analysis, according to NBC.Researchers discovered that exposure to nitrogen dioxide for up to five days before resulted in a nearly 30% increased risk of stroke.

The risk increased by 26% in response to carbon monoxide exposure, 15% in response to sulfur dioxide exposure, and 5% in response to ozone exposure.Additionally, a 33% increased risk of dying from a stroke has been connected to brief exposure to nitrogen dioxide. Sulfur dioxide showed a 60% increase.Particulate matter particles that are inhaled irritate and inflame the lungs. According to Michael Kleinman, who was not involved in the research but works at the University of California, Irvine's Air Pollution Health Effects Laboratory, this sets off an immune system reaction that ultimately affects the cardiovascular system."What occurs in the lung and what occurs in the heart are directly related," he stated.The largest rise in particulate matter was observed for PM2.5 particles, which had a diameter of less than 2.5 microns.

The study concluded that exposure to PM2.5 particles was linked to a 15% higher risk of stroke. A 14% increased risk of stroke was linked to increasing exposure to PM10, whereas a 9% larger risk was linked to increased exposure to PM1.A domino impact According to Michael Kleinman, co-director of the University of California, Irvine's Air Pollution Health Effects Laboratory, breathing in particulate matter—especially the smaller molecules—causes inflammation and irritation in the lungs, which sets off the body's immune response. Kleinman was not involved in the study.According to Kleinman, this has a cascade effect on the cardiovascular system. "What occurs in the lung and what occurs in the heart are directly related," he stated. In an attempt to fend off invaders, inflammation spreads throughout the body when air pollution triggers the immune response. Because of this inflammation, blood, clots, and plaque have a harder time passing through the arteries and veins. The body produces more thrombin, a clotting agent, in the blood at the same time.

"The risk increases with the duration and intensity of an individual's exposure to air pollution," stated Dr. Julius Latorre, the head of Syracuse, New York's Upstate University Hospital Comprehensive Stroke Center, who was not involved in the new study. Because sulfur dioxide and nitrogen dioxide molecules are so small, they have a greater chance of slipping past the lung's filters and harming the body's cells or irritating the lungs to the point of an inflammatory response, according to Latorre. He continued, "This could be the reason these two pollutants were specifically associated with an increased risk of stroke death."