A Q&A With the Experts on Air Quality

After all the tests and forums, here’s what we know—and don’t know—about what we breathe.

What independent tests have been done besides the EPA's testing?
Many organizations, including NYU Medical Center, Mount Sinai Medical Center and the Columbia School of Public Health, have tested air and dust samples. Community Board 1 also hired experts to do tests. The results have mostly confirmed the EPA’s findings. The independent groups said they will continue to monitor air quality and study data already collected.

What is in the dust?
The dust is primarily crushed cement. It also contains fiberglass, silicon, metals, organic compounds (including dioxin and PCBs), gypsum, plastics and small amounts of asbestos.

What is in the air?
The air contains cement dust, silicon, fiberglass, carbon and, in some cases, asbestos. The burning of plastics can release dioxins and PCBs, but experts say that tests have shown only minute levels.

What are the immediate and long-term health effects of those pollutants?
The particulates in the air can irritate the nose, throat, lungs and eyes, causing scratchy throat, coughing, runny nose, itchy and watery eyes, and chest pains. But experts at the forums pointed out that these symptoms do not necessarily indicate a serious health hazard. “They’re annoying, but they don’t often cause long-term effects,” said Joan Redman, a pulmonologist at Bellevue Hospital and a professor at NYU Medical School. Scientists explained that pH tests of large cement particles showed high alkalinity, which irritates the nose and lungs. “The smaller particles, which can lodge deep in the lung, are more neutral and non-irritating,” said George Thurston of NYU Medical School.
Perhaps the most serious immediate health threat, the experts said, is to people with asthma, emphysema or other respiratory or cardiac problems, who should limit their exposures downtown. “Anyone with a respiratory condition is at risk of worsening the condition,” said Stephen Levin, an occupational and environmental health expert at Mount Sinai. The scientists and professors said that the collapse of the towers released a unique combination of particulates and chemicals, and that it is impossible to predict the mixture’s long-term effects. “There’s not a lot of data on low-level exposure in combination,” Dr. Forman said. “The few things we do know are all reassuring,” said William Esposito, an independent air quality tester who has been working at Ground Zero, “but there are all kinds of other factors involved, like unknown exposures and the combinations.”

What are we smelling? Is it dangerous?
That foul smell is mostly from burning plastics and other fuels. “Our noses are much more sensitive to these smells than the testing equipment is,” said Joel Forman of the Mount Sinai Pediatric Environmental Health Unit. But that doesn’t mean that we sniff out health hazards the equipment can’t detect. “These materials are toxic at levels many times higher than the levels at which we can smell things,” said Howard Kipen, a professor of environmental and community medicine at the Robert Wood Johnson Medical School.

What are the effects of these pollutants on children?
Young children are generally more vulnerable to health hazards. Children breathe faster and inhale more air in proportion to their body size than adults. Speakers at the recent health forums said that while there is no evidence that the air poses a serious risk for children, there is too little data about the effects on children to say for sure that the air is safe for them. “We don’t know a lot about the effects of those chemicals on humans generally, let alone kids,” said Dr. Forman. Frederica Perera, a professor at the Columbia University School of Public Health, said, “While risks are thought to be low in the general population, pregnant women and newborns may be more at risk if exposed.”

What special precautions should we take with our children?
Children should try to avoid prolonged or vigorous outdoor activity, and windows should be kept closed as much as possible, said Bernard Dreyer, chief of pediatrics at the NYU Medical Center. Regarding playgrounds, Dr. Forman said, "The testing that’s been done is reassuring but I’m not personally quite ready to allow young children to crawl around in playgrounds right now.” Like adults, children with asthma or other respiratory problems are at risk of worsening their condition. "Our recommendation is, if your child is a brittle asthmatic and has frequent episodes, having that child in this environment is ill advised,” said Dr. Levin. Children with mild asthma who are having more frequent attacks should probably not be exposed to this environment, he added.

Is Washington Market Park safe?
Washington Market Park was closed for a week in late September and early October after tests revealed asbestos in the park. The EPA removed all the sand from the sandbox as well as a layer of surface dirt in contaminated areas. The basketball and tennis courts were also cleaned. Follow-up tests by the city, the EPA and an independent expert hired by the park board showed no remaining asbestos contamination, said Linda Lakhdhir, the board’s president. “All we can do is test and provide the information and let people make their own judgment,” she said. “I’m not going to say the park is safe. Maybe we’re not testing for something we should test for.” Lakhdhir said that the Parks Department recommended not replacing the sand, to avoid people’s tracking dust from outside the park into the sandbox.

After an initial cleaning, what should we do to keep our apartments free of potentially harmful pollutants?
Residents should take simple and sensible precautions: use wet rags or mops to wipe up new dust indoors and on window sills, and use a HEPA (high efficiency particulate) vacuum, to avoid dispersing dust back into the air; use a room air filter; take your shoes off before entering the apartment (and buy a doormat); wash your hands when you come home; and keep windows closed on smoky air days.