Investigators followed participants on average for 17 years between 2000 and 2018, when 248 adults, or 3.7%, developed blood clots necessitating hospital care. Photo by Ivan Samkov/Pexels
Long-term exposure to air pollution poses an increased risk of blood clots in deep veins, which can result in serious complications, including death, a new study indicates.
The most comprehensive U.S. study reporting on this connection with three types of air pollutants was published Thursday in the journal Blood, a publication of the American Society of Hematology. Advertisement
Air pollution exposure can lead to inflammation and contribute to blood clotting. It has long been linked to cardiovascular and respiratory diseases, and earlier research also suggested an association with venous thromboembolism, or VTE.
Up to 900,000 Americans experience VTE annually. Age, surgery, extended periods of inactivity, heart disease, pregnancy and genetics also can raise the risk.
VTE includes deep vein thrombosis, when a blood clot forms in a deep vein of the legs, arms or an internal organ, and pulmonary embolism, which strikes when a blood clot breaks off from such a vein and travels to the lungs. Advertisement
“Air pollution affects nearly everyone to some degree,” lead author Pamela Lutsey told UPI.
Blood clots “are an underappreciated health condition,” said Lutsey, a professor at the University of Minnesota’s Division of Epidemiology & Community Health in Minneapolis.
The study included 6,651 adults living in or near New York, Baltimore, Chicago, Los Angeles, Minneapolis and Winston-Salem, N.C.
Investigators followed participants on average for 17 years between 2000 and 2018, when 248 adults, or 3.7%, developed blood clots necessitating hospital care.
Participants with higher overall air pollution exposure developed a 39% elevated VTE-associated risk compared to those exposed to lower levels.
People with increased exposure to oxides of nitrogen and nitrogen dioxide — pollutants most frequently found from vehicle exhaust — had a 121% to 174% heightened risk, respectively.
“Our findings add to accumulating evidence that air pollution contributes to a wide variety of adverse health events,” Lutsey said.
People inhale tiny air pollution particles emitted from coal-burning power plants, forest fires and motor vehicle exhaust.
The researchers analyzed the relationship between air pollution collected through biweekly community-level monitoring, which included samples obtained from participants’ homes, and the risk of being hospitalized for venous thromboembolism.
They compared those with the greatest exposure levels — at the top 75 percentile– to those with lowest exposure — at the bottom 25 percentile. And they adjusted for variables such as age, tobacco exposure, and underlying respiratory and other health conditions. Advertisement
The research is part of the Multi-Ethnic Study of Atherosclerosis, with funding from the National Heart, Lung, and Blood Institute, National Center for Advancing Translational Sciences, and the Environmental Protection Agency.
However, “because this paper looked at long-term exposure to air pollution, which is ubiquitous and people have relatively little control over, it is hard to make concrete recommendations to reduce exposure and improve health,” Lutsey said.
Other experts commended the researchers for examining the chronic health effects of air pollution.
“The investigators used state-of -the-art air pollution exposure methods,” said Dr. Howard Kipen, a professor in the Department of Environmental and Occupational Health and Justice at Rutgers University School of Public Health in Piscataway, N.J. He was not involved in the study.
“This adds to the incontrovertible body of scientific evidence that real-world levels of pollutants significantly increase the risk of developing a host of serious, life-threatening diseases throughout the body,” Kipen said, citing cancer and diabetes as examples.
Deep-vein thrombosis is especially common in bedridden surgical patients. The risk also increases more modestly in healthy people during a long airplane flight, he said.
Citizens depend on the federal government, particularly the EPA, to decrease pollution under the Clean Air Act, and such studies guide informed decisions, Kipen noted. Advertisement
People should ask their doctors about preventive measures in anticipating immobility after significant surgery. And flexing leg muscles and walking and standing is helpful during flights longer than four hours, he said.
Anyone living around increased air pollution should be vigilant about lowering VTE risk with a heart-healthy diet and weight-loss regimen that includes regular exercise, said Dr. Arman Qamar, director of the Center for Cardiovascular Personalized Medicine at Endeavor Health in Glenview, Ill.
Estrogen-based medications also raise blood clot risk, so vulnerable people should discuss alternatives with their doctors, Qamar said.
Nonetheless, Dr. Gopal Allada, a pulmonologist at Oregon Health & Science University in Portland, noted that two simultaneous events don’t prove a causal link.
“There may be something else that is causing increased cases of VTE more commonly in areas with greater air pollution,” Allada said.
