Between September 11th and Christmas, 2001, the EPA conducted more than 7,500 air quality tests where the Twin Towers once stood, looking for a wide variety of carcinogens and other compounds such as dioxin, lead, and asbestos. Government agencies were trying to determine if airborne particulates and gas phase compounds generated by the crumbling and burning of 220 floors worth of building materials, office furniture, equipment, and jet fuel posed any significant long-term health risks to people who had been in the area since the time of the attacks.

The tests indicate that a unique microclimate of environmental contaminants was created at the site, unlike any previously known. Tests showed that the air had been found to contain cement dust, fiberglass, asbestos, a variety of polycyclic aromatic hydrocarbons, dioxin, lead, mercury, and volatile organic compounds such as benzene, toluene, and formaldehyde.

For the most part, airborne concentrations were within regulations, although testing didn’t begin until the day after the towers collapsed, and it’s certainly fair to assume that the first 24 hours were responsible for the highest concentrations of many of the toxic compounds now known to have been generated. Testing after the attack showed only 29 tests out of 3,500 for asbestos had exceeded federal thresholds. The EPA criteria for dioxin were exceeded briefly during the first couple of weeks. In mid-December, however, government officials were still measuring concentrations of benzene 400 times the level permitted for a year of continuous exposure.

The majority of health officials stated officially at the time that no significant threat to workers and residents existed at ground zero. Those statements are now regarded from a historical perspective as misleading or downright false. Even at the time, reports of sore throats, coughing, asthma, cold-like symptoms, breathing problems, bronchitis, sinusitis, and reduced lung capacity continued to be reported, supporting the idea held by many that the unique mixture of contaminants may have reacted in unknown ways to produce unpredictable health concerns. In addition, there was the possibility that brief exposure to chemicals or heavy metals by pregnant women may have threatened the development of their unborn children. As a result, women who were pregnant at the time of the attack were being recruited for studies that would last several years. We now know, from numerous studies that included work from the Columbia Center for Children’s Environmental Health, or CCCEH, that the effects included shortened gestation periods, lower birth weights, genetic damage, and increased carcinogenic risks.

Although most organic compounds dissipate quickly as a result of their high vapor pressures, improper cleanup procedures could have exacerbated contamination problems by stirring up toxic-laden particulates that had settled out of the air. The main weapon against re-circulating contaminants was water – keep everything as wet as possible while cleanup activities occur. In addition, the use of particulate arresting filters was supposed to be mandatory on all vacuum operations. Heating and air conditioning systems that had been infiltrated with dust generated from the site should have been thoroughly cleaned, with fresh filters installed before they were restarted. Ordinary fiberglass filters were replaced initially with the more expensive high-efficiency particulate arresting (HEPA) filters in all heating and air conditioning systems that could tolerate reduced airflow until such time that cleaning activities inside and outside buildings were completed. Once the contaminants were gone, it was assumed that it would be safe to return to normal filters.

Mount Sinai Medical Center’s ongoing medical monitoring program, which has treated more than 26,000 people exposed to fallout from the WTC, has proved that exposure to the toxic dust cocktails of the twin towers’ collapse has caused persistent illnesses such as asthma, reactive airway disease, and shortness of breath. The monitoring program re-examined more than 3,160 responders between 2004 and 2007, and found more than 24% had abnormal lung function.

The persistent medical problems related to the WTC attacks became the focus of the Daily News Editorial Board’s editorial series, “9/11: The Forgotten Victims,” winning a Pulitzer Prize in 2007. As a direct result of that series, the Department of Health and Human Services gave $75 million to be used in monitoring and providing health care to 9/11 volunteers, becoming the first federal funds dedicated to 9/11 health problems.

The medical legacy of the collapse of the Twin Towers will far outlast any economic damage done to the country, as people who did not die during the attack or soon thereafter will carry the biological damage throughout the rest of their shortened lives. It’s important to remain committed to those who gave of themselves so willingly during the crisis.