CNN - Exposure to the enormous cloud of toxins, dust and debris that resulted from the terrorist attack on the World Trade Center in 2001 has been linked to an increased risk of cardiovascular disease among first-responder firefighters, according to a new study.

The study, published in the medical journal JAMA Network Open on Friday, found that both immediate and repeated exposures to the dust during the months of cleanup following the attack was associated with elevated cardiovascular disease risk that lasted for up to 16 years.

Among the firefighters in the study, "the ones with the greatest exposure -- those present in the morning of 9/11 -- had a higher risk than those who showed up later in the week," said Dr. David Prezant, chief medical officer for the Fire Department of the City of New York and a professor at the Albert Einstein College of Medicine, who was senior author of the new study.