It’s been almost 16 years since the Sept. 11 terrorist attacks, and the damage is still being done.

Children who lived in lower Manhattan and were exposed to toxic clouds of debris from the terrorist attacks are already showing increased risk of future heart disease, according to a new analysis published in the journal Environment International.

Researchers from NYU Langone Health looked at blood tests of 308 children, about half of whom were in contact with the dust on and after 9/11. They found that kids whose blood contained chemicals known to have been in the debris had elevated levels of artery-hardening fats in their blood.

Those chemicals came from the fumes emitted as electronics and furniture burned during the attacks. Children who lived near the World Trade Center were exposed to much higher levels of these chemicals than children who were not in the city on the day of the attack.

If left unchecked, higher levels of fat in the blood can lead to blood-vessel blockages and heart attacks.

“Since 9/11, we have focused a lot of attention on the psychological and mental fallout from witnessing the tragedy, but only now are the potential physical consequences of being within the disaster zone itself becoming clear,” says lead study investigator and health epidemiologist Leonardo Trasande, an associate professor at NYU School of Medicine, in a statement.

The damage isn’t necessarily irreparable, however. Trasande says these risk factors can be addressed through diet and exercise.

“[Our study] offers hope that early intervention can alleviate some of the dangers to health posed by the disaster,” he adds.