Many workers who cleared debris from the site of the World Trade Centre attack of September 11, 2001 are showing symptoms of acute respiratory diseases, according to a health assessment conducted by the us-based Johns Hopkins Bloomberg School of Public Health. The investigators believe the respiratory problems may be associated with exposure to dust and airborne contaminants. Since the investigators only looked at short-term health effects, they said more research is needed to determine if there is any long-term health risk to the workers.

"Many of the workers we assessed reported coughing, wheezing and sore throats. These symptoms seemed to increase the longer they worked at the site. The good news is that we did not find unhealthy levels of asbestos, but we don't know what the long-term health risks may be regarding exposure to other airborne contaminants at the site,' explains Alison S Geyh, chief investigator of the assessment.