Ground Zero Air Polluted by Diesel Equipment

NEW YORK, New York, September 25, 2002 (ENS) - Diesel pollution from construction equipment and diesel generators at the site of the collapsed World Trade Center towers poses a health threat to some lower Manhattan residents, a new study warns. The same study also provides some good news for local residents, suggesting that apartments and offices near Ground Zero should, after a proper cleaning, be safe for living and working.

Professor Thomas Cahill from the University of California at Davis said he found little evidence that very fine pollution particles remain in indoor spaces near Ground Zero once the areas have been cleaned according to U.S. Environmental Protection Agency (EPA) guidelines.


The heavy equipment used for the cleanup at the World Trade Center, and now for new construction, pollutes the air with diesel fumes. (Photo by Larry Lerner, courtesy Federal Emergency Management Agency (FEMA))
But his research, performed in collaboration with the American Lung Association of the city of New York, also shows that the concentration of diesel pollution in lower Manhattan is quite high, which could cause breathing problems in some people.

Air samples collected for the study "confirmed that diesel pollution from the countless vehicles involved in the recovery and rebuilding effort is heavily concentrated downtown," said Cahill.

The recovery, cleanup and rebuilding of the World Trade Center site all employ large fleets of diesel vehicles, from construction trucks to back up generators. At the three sites closest to Ground Zero where samples for the study were collected, the levels of sulfur, which indicates the presence of diesel pollution, were much higher than at uptown sites.

Diesel exhaust particles are known to worsen allergies, trigger asthma episodes and decrease lung function in otherwise healthy individuals, according to the American Lung Association. In a study released earlier this month, the EPA concluded that inhalation of diesel exhaust particles "is likely to pose a lung cancer hazard to humans, as well as damage the lung in other ways depending on exposure."

The emissions from diesel engines also cause fine particle and ozone formation. Even before the September 11 terrorist attacks, New York City's air violated the health standards for both of these pollutants.


UC Davis professor Thomas Cahill describes his air quality findings to an ABC News film crew at the World Trade Center site on February 23, 2002. (Photo by Sylvia Wright, courtesy UC Davis)
"The equipment that was rolled in expressly to help this city rebuild and heal is in fact, contributing to long term health concerns," said Peter Iwanowicz, director of environmental health for the American Lung Association of New York State.

The American Lung Association recommends that all equipment and vehicles running on diesel fuel be supplied with low sulfur fuel, containing 30 parts per million of sulfur or less. According to the Manufacturers of Emission Controls Association, a diesel engine running on low sulfur fuel and using sophisticated emissions filters can have 90 percent less emissions than one that does not.

New York City Transit is now running all of their buses on low sulfur fuel and is installing the filters as well, so both are known to be available in the region. New York City Council member Alan Gerson has introduced legislation to require that Trade Center related vehicles use both lower sulfur fuel and these filters.

The report's conclusions about the quality of lower Manhattan's indoor air were based on samples collected by the UC Davis DELTA Group (for Detection and Evaluation of Long-range Transport of Aerosols), a collaborative association of aerosol scientists at several universities and national laboratories. The DELTA Group has made detailed studies of aerosols from the 1991 Gulf War oil fires, volcanic eruptions and global dust storms.


This photo, shot from a New York City police helicopter just moments after the collapse of the second World Trade Center tower on September 11, 2001, shows the enormous cloud of dust and smoke that blanketed lower Manhattan. (Photo courtesy EPA)
In February, the DELTA Group released what is still the most thorough analysis of the dust and smoke blown through lower Manhattan after the World Trade Center towers collapsed. That analysis found unprecedented clouds of very fine particle air pollutants.

For the new study of indoor air, samples were collected in May at four sites in lower Manhattan -two apartments and two offices - to evaluate the persistence of very fine aerosols in indoor areas near the trade center.

The samples were analyzed for very fine particles of silicon, sulfur (sulfate), vanadium, nickel and lead, all of which the DELTA group had found to be abundant in outdoor air in October 2001. Results were compared against clean control sites and against an average exposure rate about one mile north-northeast of the trade center site.

The results indicate that, other than sulfur from diesel fumes, the amounts of toxins present at the four indoor sites studied were low and well within public health guidelines.

"We knew that large amounts of very fine particles, which can get deep into a person's lungs and cause serious health problems, were released from the super hot Trade Center debris piles," said Cahill, an international authority on the constituents and transport of airborne particles. "Our new analysis shows that in the sites we tested, those very fine particles either never penetrated the indoor spaces or were effectively removed by professional cleaning."


Dust and smoke continue to rise from the World Trade Center site on September 27, 2001. (Photo by Bri Rodriguez, courtesy FEMA)
The American Lung Association said the UC Davis results should reassure New Yorkers who have had their homes and offices professionally cleaned by a licensed asbestos and lead abatement contractor. The association urged all residents who live in the affected area and who have not yet conducted a proper inspection and cleaning to contact local agencies to schedule one soon.

"This is good news for the residents and workers of lower Manhattan," said Iwanowicz. "We now know that when proper testing and mitigation are conducted, indoor spaces are as clean as, or in some instances cleaner than, before September 11."

For EPA approved cleanup and testing of indoor spaces in lower Manhattan, visit:

For more information about the UC Davis DELTA Group, visit: