Following the 9/11 terror attacks, many people wondered how the smoke and dust, which consisted of heavy metals, glass, and cement, would affect first responders’ health. Many of them were exposed to the initial dust cloud, and then spent months helping with the recovery. A recent study looking into the long-term effects has now found a link between exposure to these pollutants and kidney damage.

“Our study shows the first responders with the highest exposure to the 9/11 particulate matter had significantly greater levels of albumin in their urine than the first responders in the study with low exposure levels,” lead researcher Dr. Mary Ann McLaughlin, of the WTC-CHEST Program at the Icahn School of Medicine of Mount Sinai Hospital in New York, said in a statement.

“We believe high exposure to the massive dust cloud of air pollution at Ground Zero may have extremely inflamed the endothelial lining of blood vessels leading to the kidneys causing kidney malfunction and the development of kidney damage in first responders.”

Albumin, one of the main proteins found in blood, is too large to get through a healthy kidneys’ filters and into the urine. Damaged kidneys allow albumin and other proteins to leak through — a condition called albuminuria. The inabilit of kidneys to filter effectively is a sign of chronic kidney disease and a precursor to other health problems, according to the National Institutes of Health. Some patients with albuminuria may experience swelling in their hands, feet, abdomen, or face, because there are no longer enough proteins in their blood to help fluid remain in the blood vessels.

“I always get tired.” Elizabeth Lugo, 46, a retired police officer who was among the study’s participants, told the Daily News. “You just don’t feel good — you can see it in the face, it gets swollen. The stomach too. It feels like I have a kidney stone.”

For the study, the researchers looked at the urine samples of 183 first responders to the World Trade Center. They also recorded information pertaining to each participant’s time of arrival, proximity, duration, and level of exposure to contaminants. They found that increased levels of albumin correlated to higher levels of exposure.

The study, which was presented at the annual meeting of the American Society of Nephrology, paves “the way for future early diagnosis and care of these first responders’ impaired kidney health,” Dr. McLaughlin said in the statement.

Dr. McLaughlin was also involved in a 2011 study that found that first responders could be more likely to develop heart disease than those who took part in recovery efforts after Sept. 13. These first responders had significantly more damage to their blood vessel walls in the form of atherosclerosis, the hardening of the arteries.