One-fourth of New York City's 10,800 firefighters and emergency medical staffers and many residents near Ground Zero have fallen ill, and the long-term effects are unknown, according to a report by Consumer Health Interactive.

Common symptoms include shortness of breath, frequent nosebleeds and skin rashes, wheezing, sinusitis, chest tightness, burning in the nose, throat or lungs, as well as digestive problems, according to the Mount Sinai School of Medicine. Many people who already had asthma also suffered an upsurge in symptoms.

Dust and smoke from fires at Ground Zero included a toxic mix of silica, gypsum, fiberglass, paper, polyvinyl chlorides, pulverized concrete, cancer-causing benzene and asbestos.

There's no consensus among scientists and public health officials on the long-term health risks of working and living at Ground Zero, according to the report. More than 60 health effects investigations are under way.