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Air Supply

Smoke gets in your eyes — and if it's toxic, watch out. When the World Trade Center exploded in a cloud of dust on September 11, it released a witches' brew of compounds and chemicals. Those, in turn, created a yellow fog that enveloped much of lower Manhattan for at least a week. Five months later, the still-burning fire at the foot of the towers complex was finally extinguished, but concerns linger on. How much potential for long-term harm did the acrid smoke contain?

According to the New York Committee on Occupational Safety and Health (NYCOSH), indoor air becomes contaminated when toxic substances combine with inadequate building ventilation. That causes health problems such as eye, nose, and throat irritation; sinus discomfort; headaches; sneezing and coughing; respiratory infections; and fatigue.

Poor indoor air quality can be traced to many sources. Buildings are often designed or renovated without attention to ventilation, resulting in sealed windows, blocked vents and a general lack of fresh air. Home office equipment such as photocopiers may give off ozone, which irritates the eyes and the respiratory tract, causes headaches, and has been shown to cause adverse genetic effects. Ink toner and many other common office supplies are also dangerous, releasing vapors and dusts that can cause a variety of skin and respiratory problems.

A variety of solvents are used in cleaning, roofing, painting, and renovation work and they can cause skin dryness, respiratory irritation, and with greater exposure, dizziness or nausea. Two particularly dangerous groups of chemicals are insecticides and pesticides. These highly toxic substances can remain in the air long after being sprayed. They are known to cause cancer and birth defects and they also irritate the skin, eyes, and lungs.


In the aftermath of September 11, while the heavy fumes still swirled, New York's contractors, landlords, managing agents, and environmental consultants were at work repairing and "remediating" the damage. Like the rescue workers who hunted through the rubble for the wounded, they really had no choice but to pitch in. Among the first to thoroughly clean and restore his property was Ric Clark of Brookfield Properties, who managed the daunting task of restoring service to 1 Liberty Plaza, a towering office building on the edge of the WTC Plaza. The job was completed by October 25, according to Crain's New York Business.

Among the contractors who worked for Brookfield, undertaking the task of cleaning 25,000 feet of air ducts and installing advanced HEPA filters, was AFGO Mechanical Services. Says AFGO CEO Glenn Udell: "So many people pulled together on these jobs. There was a huge overlap of trades and efforts on behalf of so many different companies. It ended up being a real common effort." Like many HVAC and construction companies, AFGO volunteered its labor when the towers fell.

Since that day, the company has seen requests for activated charcoal HEPA filters, which provide the purest filtered air, skyrocket in the downtown area in the two to three hundred residential, commercial, hi-rise, and institutional buildings they service. Though these filters are two to three times as expensive as conventional filters, customers are willing to buy them to make sure the air coming in from outside is clean.

"We've always suggested that our property managers take a look at their ducts [and] filter intake, and take readings on ambient air," Udell says. "A lot of equipment is being changed out; ductwork sheet metal has shifted, and now the ducts have to be redone and retested to be leakproof, so our customers can be sure they're holding the air properly." When building owners have concerns about what substances may be present in their buildings, Udell suggests they retain an environmental consulting firm, so as to assess exposures and develop a scientifically sound clean-up plan.

One of the most prominent environmental consultants post-9/11 in lower Manhattan is Howard Bader, CEO of H. A. Bader. His firm was retained not only by Stuyvesant High School, at the corner of Chambers and West Streets, but also by the large municipal union District Council 37. At 125 Barclay Street, DC 37 is just down the block from 7 World Trade Center, the site of former Mayor Rudolph Giuliani's emergency operations center, which collapsed with its heavy load of diesel fuel hours after the twin towers came down. The WTC 7 site had the highest readings in the area of dioxin, a dangerous carcinogen that is produced in many types of fires. This was because there was a Con Ed transformer station in the tower that burned, Bader says. Transformer oil containing polychlorinated biphenyls, or PCBs, produces dioxin when burned.

DC 37 Occupational Safety and Health Director Lee Clarke's biggest problem after September 11, however, was mold, which formed throughout the building's basement because of flooding. "We completely gutted the basement," she says. "There was mold contamination because this area lost power, and our pumps weren't working and we were flooded. The [central air] ventilating system wasn't turned on for months after 9/11, so the air was less of a concern than the mold situation."

Bader says that small amounts of three substances — asbestos, lead, and dioxin — pose the greatest hazard to returning residents. But it's not always easy to know whether they still linger on in your home. "If you came back from two weeks to a month after the disaster, any accumulated dust should have been obvious. It's fluffy gray. Most residences do not have outdoor air vents that take in outdoor air, so, if their windows were not blown out, most of the apartments didn't get that much dust in them."

He notes that city agencies, including the New York City Department of Health, have found toxic dust inside both commercial and residential buildings near Ground Zero. "Right now, the EPA [Environmental Protection Agency] has started a project to clean over 200 buildings in the area. What hasn't been discussed is how they are going to handle the air conditioning units. This is a big concern, and those should be professionally cleaned," he says. "Dioxin is toxic in even extremely small quantities. Asbestos is also a potent carcinogen. And the biggest concern with lead is for children and women of childbearing age."


If homeowners are unsure about what may still be present in their homes, testing by a qualified environmental lab may be worth doing. Bader recommends that members of a co-op or a condo pool resources and test representative apartments and areas, since it can be expensive. Dioxin tests are very costly at $800 each. Tests for asbestos and lead, however, are considerably cheaper, with an outlay of $500 to $600 sufficient to sample a range of areas to get a good idea of exposure levels.

Although there are no legal standards for indoor air quality, the World Trade Center disaster has become an exception to this rule, informed sources reported. Any resident living south of Canal Street will be able to get a cleaning and air test done by the EPA for free. What exactly the air test would consist of and how thorough the cleaning would be was not available in early May. Another issue which is being debated are the consequences for buildings if some owners opt to have the cleaning done, but others refuse, leaving their spaces potentially still contaminated.

Industrial hygienist Carrie Loewenherz has toured Ground Zero many times since 9/11 as a staff scientist for the New York Committee for Occupational Safety and Health, which advises consumers, environmental groups, and unions on environmental science and standards. She realizes that she is working in an area where scientific knowledge is still in relative infancy and where many questions remain.

"There are no enforceable indoor air quality standards," she notes. Although some states, like California, are enacting laws dealing with the regulation of specific toxic hazards such as mold, New York State does not set permissible levels for toxic materials in the home. For this reason, homeowners have the extra burden of having to decide for themselves how much is a bad thing.

In the days following 9/11, Loewenherz field-tested both air and ground samples at the site, and reviewed standards for personal protection used by rescue workers. She studied cases of "firefighter's cough," both in emergency personnel and residential cleanup workers, which is a short-term response to acute exposure to WTC dust and smoke.

"Whether your building is safe is dependent on its history, and whether or not a proper cleanup was conducted post-9/11 — not only interior, but exterior," she says. She adds that a ventilation system, even if it was cleaned after 9/11, can be recontaminated by the WTC site recovery and excavation work that has been taking place.

"Besides asbestos, NYCOSH is also concerned about levels of mercury, lead, and other heavy metals," she says. "The pulverized dust itself can easily become airborne. It's alkaline in nature and a respiratory irritant. Ventilation is one pathway for contaminants to enter your building or your living space, so unless those systems are properly maintained and the air coming in is properly filtered, there is some concern around that."

NYCOSH's website,, sports an excellent 9/11-related fact sheet that outlines steps which a building owner should take in addressing his/her ventilation system as a potential source of hazardous contamination (see "What You Can Do: A Primer," page 46). In addition, the federal EPA provides introductory treatments of indoor air quality, as do numerous other environmental organizations.

The message from medical professionals has been clear from Day One, Loewenherz says. "People with asthma and other pre-existing medical conditions are more sensitive to these contaminants and they should take special note. Since 9/11, the level of concern among the general public has dropped off significantly, but the concern has remained for people in buildings which may have been improperly cleaned and for those workers actively involved in the cleaning up of dust themselves."


Those firms actively involved with cleaning chutes have faced increased challenges and increased business activity since September 11. Maxons Restorations, a disaster restoration company based in New York City, typically has about 200 workers on staff. For three months following the disaster, it increased its size to 1,500 workers per day. Whereas they often handle one or two calls daily, up to 200 a day were coming in for the first six months. Damon Gersh, president and CEO, had to create six or seven layers of management to handle the calls, splitting the disaster site into four zones and opening field offices. For its efforts, the company won an award from Fast Company Magazine.

"This was the biggest challenge we ever faced," he says. "There was an unprecedented amount of residue from the accident and it covered everything. We had to clean the entire building, from dismantling light fixtures and air conditioner units, to cleaning one book at a time, one shelf at a time."

The residue, which Gersh compares to the fine white talc that results from sanding drywall compound, was particularly difficult to clean. After vacuuming apartment units, workers used chemical sponges and cleaning compounds by hand, often having to go over areas two or three times. A one-bedroom apartment took five workers about two days to clean, Gersh estimates.

The other consideration, and one just as important, was the air system. Fresh air intake systems, unless turned off, took in huge amounts of the dust, enough to overwhelm the system. So, much of the dust made it through the filters and was dispersed throughout the entire building. The ducts and air units were thus lined with powder.

"Some buildings tried to get in-house personnel to clean, but they could only do what was obvious," notes Gersh. "The air system is a vital component. If you clean all the public areas and ignore the air, you end up re-exposing the area you've already cleaned once the air is turned on." Although not as important as the fresh air system, exhaust shafts also need to be cleaned. A draft may have carried dust into them. "You have to clean every inch of everything," says Gersh.

Craig Berlin, president of ChuteMaster Indoor Environmental, says that 9/11 has created "a renewed interest in the quality of indoor air. People are thinking about how buildings breathe. It's not necessarily a matter of keeping the contaminants out; it's a matter of keeping buildings circulating air and breathing. Most buildings in Manhattan don't take the time to check if the roof fans are even working; a lot of them put them on a timer and run them only a few hours a day. That's changing."

Steve Wolfson, president of Environmental Cleaning Services, which is involved in cleaning a dozen properties in the area of Ground Zero, says that most of the debris from the towers is made up of pulverized construction materials, including cement, bricks, and mortar. "A lot of people are under the impression that the towers had a huge amount of asbestos in them; that's not the case." He says that the disaster has raised the profile of indoor air quality throughout the city.

"Before 9/11, it took a lot of teaching and explaining to people why they should be concerned about indoor air quality. What most people didn't understand is that, according to the EPA, air pollution from indoor air can be 100 times more damaging than air outside, especially because we are making buildings air tight and soundproof, so all of the contaminants and germs are being recycled inside that closed system. Property managers, boards and residents have a motto:

'If it's not broken, don't fix it.' Since 9/11, a lot of people have been slapped in the face and been woken up to what might be in their vent work — whether it's spores, mildew, animal dander, or debris from 9/11. It's something we should all be concerned about."

Berlin cautions that promises to "cure" a building are often misleading, because only environmental scientists can definitively monitor for hazard abatement. He stresses that cleaning with dry vacuum cleaners may harm more than it helps, spreading particulates into the air via the machine's exhaust. "It's imperative that people clean with HEPA-powered equipment [which filters the exhaust]."

One thing that greatly concerns Berlin is that, even after 9/11, political leaders are considering measures that will increase air pollution and particulates. "There is casual conversation about burning trash again," he says. "I can't think of anything that's more contrary to environmentalism than that, but the monetary issue is coming into play. The fat days are over, and we may be heading back to incinerators. The little gray flakes that we all forgot about from 20 years ago, that used to come drifting in your window, they may be coming back. I can't believe [the politicians] are even discussing it again."


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