From asthma to lung disease to cancer, the list of diseases attributable to air pollution is extensive. Researchers at the University of Minnesota School of Public Health (SPH) add to that list with a new study that finds a potential link between air pollution and venous thromboembolism (VTE)—a condition where blood clots form in deep veins and may travel to the lungs, causing serious and potentially life-threatening health risks.

VTE, which can refer to blood clots occurring deep in a vein (deep vein thrombosis, or DVT) or to blood clots that travel to the lungs (pulmonary embolism, or PE), affects about one million Americans annually. VTE is the third most common vascular diagnosis in the U.S., after heart attack and stroke. While connections between elevated risk of VTE and polluted air have been suspected, previous U.S.-based studies on the topic have been limited.

In their groundbreaking new study, SPH researchers tracked more than 6,600 participants from six U.S. communities over the course of 17 years. The study assessed individuals’ long-term exposure to four common air pollutants: fine particulate matter, nitrogen dioxide, nitrogen oxides, and ozone. Pollution levels were estimated based on participants’ home addresses and updated biweekly over the course of 17 years. The study, published in Blood, found:

• Higher concentrations of all pollutants except for ozone were associated with a greater risk of VTE. At specific exposure levels, the study found a:
  • 43% greater VTE risk associated with exposure to elevated levels of fine particulate matter (PM2.5).
  • 2.8 times greater risk of VTE associated with nitrogen dioxide exposure.
  • 2.3 times greater risk with elevated nitrogen oxides exposure.
  • Ozone was not significantly associated with an increased risk of VTE.

• After controlling for individual behaviors and other factors, air pollution is independently associated with VTE. The associations between air pollution and greater risk of VTE were consistent across people who, for example, smoked or were known to have pre-existing conditions like respiratory diseases.

“This study is novel because of its prospective design and detailed collection of air pollution, updated every 2 weeks, over 17 years. It adds to mounting evidence that air pollution adversely impacts a broad range of health outcomes,” says Pamela Lutsey, SPH professor and lead author. “We found increased incidences of venous thromboembolism with exposure to some of the most common types of pollutants in the air we breathe. The findings support the case for long-term pollution-reduction efforts, as it’s clear that air pollution’s health effects extend beyond respiratory diseases and impact blood-clot risks even in otherwise healthy individuals without prior respiratory issues.”

The study points to the need for stricter air-quality regulations, suggesting that policymakers target reductions in fine particulate matter and nitrogen oxides to mitigate health risks.

Funding for the study was provided by the National Heart, Lung, and Blood Institute, the National Center for Advancing Translational Sciences and the U.S. Environmental Protection Agency.