Many workers who cleared debris from the site of the World Trade Center attack of Sept. 11 reported acute respiratory symptoms, according to a health assessment conducted by the Bloomberg School of Public Health.

The investigators believe the respiratory problems may be associated with exposure to dust and airborne contaminants at ground zero. The investigators, who looked at only short-term health effects, said more research is needed to determine if there is any long-term health risk to the workers. The assessment was conducted in collaboration with the International Brotherhood of Teamsters, and the findings were presented on Aug. 22 at a meeting for members of Teamsters Local 282 and held in Lake Success, N.Y.

"Many of the workers we assessed reported coughing, wheezing and sore throats while working at ground zero. 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 and assistant professor of environmental health sciences.

The exposure and health assessment was conducted between October 2001 and April 2002. The investigators examined the workers' airborne exposures to asbestos, particulate matter and volatile organic compounds. In October, airborne contaminants were measured at numerous locations at ground zero and on truck drivers who hauled wreckage away from the site. The respiratory health of the truck drivers and other debris-removal workers was assessed two months later. At that time, a respiratory health questionnaire was administered to the workers. In addition, lung function was measured using spirometry. Additional airborne contaminants measurements were collected in April and compared to what was measured in October.

The air monitoring effort detected small amounts of asbestos. Investigators say exposures were generally low and did not exceed health exposure guidelines.

Patrick Breysse, an investigator on the project and a professor of environmental health sciences at Hopkins, said, "Low-level exposures to asbestos occurring for a short period of time relative to a working lifetime suggest that these truck drivers are unlikely to be at a significant increased risk of asbestos-related disease."

Airborne particulate matter measured at the site was highly variable in both composition and size depending on conditions, such as how aggressively the fires were burning or how the debris was being removed.

In May, the National Institute of Environmental Health Sciences awarded the Bloomberg School a grant to continue assessing the health of workers involved in the cleanup of the site. Over the next year, Geyh and her colleagues will develop a registry of the 6,000 to 7,000 workers that will be used for future health assessments.