Rescue workers and survivors of the 9/11 terrorist attacks seem to have an increased risk for heart and lung diseases years later, a new study suggests. Researchers looked at more than 8,700 people in the WTC Health Registry. This registry monitors the physical and mental health of the more than 71,000 people exposed to the air and debris after the attacks. "Our findings indicate that intense exposure on a single day -- contributes substantially to the risk of developing chronic conditions," said Dr. Robert Brackbill, from the New York City Department of Health and Mental Hygiene. Researchers identified 92 cases of heart disease, 308 cases of asthma, and 297 cases of lung conditions not involving tumors.