Auburn, Sept. 17---The recent attacks on the World Trade Center undoubtedly resulted in releases of dioxin and asbestos into the air. Still experts say there is no cause for alarm.

In fact, the biggest concern is the dust firefighters, medics and others are breathing as they carry out relief efforts at the blast site.

"I wouldn’t worry so much about exposure to dioxin and asbestos," says Dr. Jim Hairston, an Alabama Cooperative Extension System water quality scientist. "What I worry about is the dust that’s being stirred up and the fact that people involved in relief efforts are breathing it."

The dust is made up of pulverized concrete and other substances caused by the explosion of the jet fuel and the subsequent burning that occurred.

"You have this very fine powder, almost like volcanic ash, that was released into the air as a result of the explosions," Hairston says. "The problem is when you breathe this and get it into your lungs."

"It’s not as bad as asbestos, but it does have a damaging effect on the lungs. If you breathe too much of it at one time, it can even kill you."

Another potentially serious problem is the massive volume of dust that will be turned into mud during rainfall.

"When you get a major rainfall, this powder will turn to mud and wash into the voids were there still may be survivors," Hairston says. "Over time, this power, like any fine powder, will harden into a firm material."

This may also pose a long-term problem for New York City’s infrastructure, Hairston says, once the material washes into sewers and hardens.

"The rainfall transforms the dust into a liquid slush flow – a real problem during and immediately following heavy rain," Hairston says. "Once it washes into underground sewers, it won’t be easy to flush out."

As a result, he says, city workers may have to go in and dig up these sewers – a very expensive undertaking in the long term.

One major concern after the attack involved the levels of dioxin and asbestos released after the explosions.

An extremely toxic material, dioxin is released by low temperature burning of substances such as jet fuel that ignited the World Trade Center towers. Other materials within the Twin Towers may also have released dioxin during burning.

Asbestos, associated with lung cancer, is a highly heat-resistant fibrous material used routinely in building construction, especially insulation, until several years ago.

"There will be concentrations of dioxin and asbestos caused by the explosion of the jet fuel and the subsequent burning," says Hairston. "But they are not at high enough levels to cause any harm."

In fact, the Environmental Protection Agency, which has monitored air-pollution levels round the clock since the blast, says these levels have not reached what is considered upper limits for dangerous substances.

People facing the greatest risk from exposure to these substances will be those involved in cleanup efforts that will follow rescue efforts within the next few weeks, Hairston says.

While asbestos has not reached dangerous levels, EPA officials have detected elevated asbestos levels in the rubble, even though the Twin Towers were among the first buildings in the United States not constructed with asbestos. And even though the building’s steel structure was treated with a spray-on ceramic fireproofing material, this does not mean other building materials within the center did not contain asbestos, Hairston says.

"Even when a substance such as asbestos is banned, it may take years before construction materials containing asbestos are removed from the market," Hairston says. Under the circumstances, he says, it’s possible some of the building materials used to construct the Twin Towers contained asbestos."

Hairston also recommends EPA officials check for lead levels at the blast site. That’s because as a 30-year-old structure, the World Trade Center may have also contained paint and plumbing material with lead.

The Twin Towers, two of the seven buildings comprising the World Trade Center, were completed in 1973.