A groundbreaking study has revealed a troubling connection between long-term air pollution exposure and a heightened risk of venous thromboembolism (VTE), a serious condition that occurs when a blood clot forms in a vein. It can be life threatening if the clot travels to another part of the body.1

There are two types of venous thromboembolism (VTE). The first is, deep vein thrombosis (DVT), when a clot is deep in a vein, usually in the legs, arms, or pelvis. A pulmonary embolism (PE) is a life-threatening situation where a clot breaks loose and travels to the lungs, blocking blood flow.

VTE can cause swelling, pain, and redness, and if untreated, may lead to severe complications or even death. It often occurs after surgery, prolonged inactivity, or due to underlying conditions like heart disease, pregnancy, or genetic factors. Now, new research shows 

This study was conducted as part of the Multi-Ethnic Study of Atherosclerosis (MESA), involving more than 6,000 people in six American cities.2 This longitudinal research highlights yet another way air pollution impacts human health – and underscores the urgent need for improved air quality.

An infographic explaining the “lingo about blood clots... Deep vein thrombosis (DVT): Blood clot located in a deep vein, usually in a leg or arm. Pulmonary embolism (PE): Blood clot that has traveled from a deep vein to a lung. DVT and PE are also know as VTE (venous thromboembolism).”

What the Study Found

The study followed 6,651 adults in the United States over an average of 17 years, from 2000 to 2018. These participants lived in or near six major metropolitan areas: New York, Baltimore, Chicago, Los Angeles, Minneapolis, and Winston-Salem, North Carolina.3

Participants represented four racial and ethnic groups – Hispanic, non-Hispanic Black, non-Hispanic White, and non-Hispanic Chinese – and were selected to be free of heart disease and other serious conditions at the start.

Air pollution exposure was assessed using a detailed residence-specific spatio-temporal modeling system. This system combined air quality data from the EPA, community measurements, and home-specific data to estimate participants’ long-term exposure to pollutants like PM2.5 and nitrogen oxides. The researchers excluded individuals with incomplete data, those on anticoagulants, and those missing key covariates, resulting in a robust dataset.

This careful design allowed the study to link pollution exposure to an increased risk of blood clots while accounting for various potential confounding factors. During the study, 248 individuals (3.7% of the sample) developed blood clots in deep veins that required hospital care.

Key findings revealed that greater long-term exposure to air pollution increased the likelihood of VTE. Depending on the type of pollutant, the risk ranged from a 39% increase to more than doubling. Specifically:

  • Exposure to fine particulate matter (PM2.5)  was associated with a 39% increased risk of VTE. These particles are 2.5 micrometers or smaller and commonly found in smoke from coal-burning power plants, forest fires, motor vehicle exhaust, and many other sources.
  • Exposure to oxides of nitrogen (NOx) and nitrogen dioxide (NO2), pollutants primarily generated by vehicle emissions, was linked to a staggering 121% to 174% increased risk.

Infographic explaining: “Blood clots affect many people… 900,000 each year (VTE affects as many as 900,000 Americans each year). 3 in 10 people who have a blood clot will have another episode within 10 years.” The number 900,000 is written in large red numbers. There are also ten graphics of people, 3 of them are red to represent the 3 in 10 who will have another blood clot.

 

How Air Pollution Impacts Blood Clot Risk

Air pollution exacerbates this risk of VTE by causing inflammation and enhanced blood clotting, which have already been linked to cardiovascular and respiratory diseases. Blood clots can be dangerous because they block normal blood flow, which is essential for delivering oxygen and nutrients to tissues and organs. 

The comprehensive scope of this study sets it apart from others. To track exposure, researchers used extensive biweekly community-level air pollution monitoring, including samples from participants’ homes. They also controlled for other variables that could affect VTE risk, such as age, smoking, and underlying health conditions.

Infographic explaining how deadly blood clots are. “As many as 100,000 people die of blood clots each year. (With a red map of the USA)... 1 of 4 people who have a PE die without warning (with 4 people, 1 of whom is red)... PE is a leading cause of death in a woman during pregnancy or just after having a baby. (With a side view of a pregnant woman in red)... Blood clots are a leading cause of death in people with cancer after the cancer itself. (With a white ribbon).”

The Broader Implications

VTE is a major public health concern, affecting up to 900,000 Americans annually.4 While surgery, long periods of inactivity, and genetic predispositions are known risk factors, this study emphasizes the significant role environmental factors like air pollution play in increasing susceptibility.

For policymakers, the findings highlight the critical need to tighten air quality regulations and reduce emissions, particularly in urban areas where residents face the greatest exposure.

Infographic explaining, “Blood Clots Are Costly,” with two major statistics. 1. Blood clots cost the [USA] up to $10 billion each year. (With graphics of ten stacks of money, in gray and the words: “10 BILLION DOLLARS”.) 2. Treatment can be as much as $15,000 to $20,000 per person and often results in readmission to the hospital. (With “$15K to 20K” in a large font.)

Protecting Yourself from Air Pollution

Reducing personal exposure to air pollution can help mitigate health risks:

  • Use a high-quality air purifier: Devices like the Austin Air HealthMate Plus are designed to filter out PM2.5, NOx, and other harmful pollutants.
  • Limit outdoor activities during high pollution days: Check air quality indexes and avoid heavy exertion when pollution levels are high.
  • Advocate for cleaner air: Support local and national efforts to reduce emissions and promote cleaner energy sources.

 

A Call to Action

This study serves as a powerful reminder of the far-reaching impacts of air pollution. Beyond its well-documented links to heart and lung diseases, the connection to VTE adds another layer of urgency to addressing air quality. By investing in cleaner air solutions, both at an individual and societal level, we can protect countless lives from the hidden dangers lurking in the air we breathe.

 

IMAGE CREDIT: All of the graphics for this blog were created by the CDC. Click here to view the full image.

 

 

REFERENCES

1 What is Venous Thromboembolism? (2023 Nov 13). American Heart Association. https://www.heart.org/en/health-topics/venous-thromboembolism/what-is-venous-thromboembolism-vte. 

2 About – The Multi-Ethnic Study of Atherosclerosis. (2020). Department of Biostatistics at University of Washington. https://internal.mesa-nhlbi.org/about. 

3 Lutsey PL, Misialek JR, Young MT, et al. (2024 Dec 12). Air pollution is associated with increased risk of venous thromboembolism: the Multi-Ethnic Study of Atherosclerosis. Blood. doi: 10.1182/blood.2024026399.

4 Impact Of Blood Clots On The United States Infographic. (2024 May 15). Centers for Disease Control. https://www.cdc.gov/blood-clots/toolkit/impact-of-blood-clots.html.

Austin Team
Austin Team