The impact of September 11th is still being felt, not just by victims' families, but by those who have gotten sick since.
Nearly 3,000 people were killed in the attacks, and nearly 2,400 others have died from 9/11-related illnesses since.
There are about 50,000 first responders among those whose health is being monitored.
Dr. Michael Crane, the director of the World Trade Center Health program at Mt. Sinai, gave NY1 an idea of what kinds of conditions medical experts continue to look out for.
"Just to put it in perspective, everybody ages, right, and as you age, even in the normal population you have higher risks of things like cancer. That's true of our population, and the increase that we're seeing in cancer is not huge, it's not multiples of the risk, but there is a substantial increase in many of the cancers. We are going to see more of that. We're going to see more mental health issues. And we're concerned about things like these neuro-degenerative track conditions. We're concerned about Alzheimer's disease, cognitive problems, all of that."
The Mt. Sinai program is one of several organizations that provides free medical monitoring, treatment, mental health services and counseling to some 24,000 first responders and others who were exposed to the toxic dust at the World Trade Center site.