New York, Jul 17 (IANS): People who were exposed to the dust cloud or sustained physical injuries during the terrorist attacks on the World Trade Centre on September 11, 2001, may be at an increased long-term risk of developing asthma and heart attack, researchers have found.

"Our findings indicate that intense exposure on a single day -- the first day of the disaster -- contributes substantially to the risk of developing chronic conditions," said Robert Brackbill from the New York City Department of Health and Mental Hygiene.

The findings showed that individuals exposed to dust had a higher risk of non-neoplastic lung disease (lung conditions not involving tumours) other than asthma, while dust exposure on its own was associated with an increased risk of asthma.

The number of types of injuries, such as fractures, head injuries, or sprains, a person sustained on 9/11 was associated with an increased risk of angina or heart attack in a dose-dependent manner, which means that the risk of having angina or a heart attack increased with every additional injury type, the researchers said.

For the study, published in the journal Injury Epidemiology, the team enrolled 8,701 people to examine the association between physical injury or acute exposure to the dust cloud on the morning of September 11, 2001, and chronic disease up to 10 to 11 years later.

The researchers found that there were 92 incident cases of heart disease, 308 cases of asthma, and 297 cases of non-neoplastic lung disease among 7,503 area workers, 249 rescue workers, 131 residents and 818 passersby.