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Air and water monitoring


The federal EPA Region II began taking samples of air and dust a few days after the terrorist attacks occurred. It also gathered data on drinking water, river water and sediments. So did the state Department of Environmental Conservation.

A challenge for local officials was interpreting environmental monitoring data from the various agencies—as different agencies were coming up with different levels and measuring for different contaminants. According to the Region, it “used established standards where they were available and modified guidelines” to produce benchmarks. For example, it used PELs (Permissable Exposure Limits) for lead, certain volatile organic compounds (VOCs), and asbestos. Otherwise it put together ad hoc benchmarks, for substances like dioxin and PCBs.

Air monitor near a debris pile.
Photo: EPA (air monitor)

EPA was available to the city for the health data it needed, but its samples were supplemented by samples taken by other agencies. Among the many agencies with responsibility for protecting health, safety and the environment there was the city Department of Health, the state and various federal agencies, including FEMA, as well as EPA. But their sampling methodology and evaluation criteria were different.

Various agencies were sampling for different toxicants, and, to make matters more complicated, there were different toxicological criteria among different agencies. For some compounds, there were no standards at all. There had never been an air quality standard for asbestos, for example, since it is normally regarded as an indoor air pollutant. And there were different standards for asbestos under various agencies. OSHA had one standard; EPA had a more protective standard. But neither of these was health-based.


“Since the first day of the World Trade Center disaster, the rapid and continued coordination among federal, state and local environmental, occupational and health agencies around such monitoring and risk communication has probably been unprecedented,” Jessica Leighton, the city DOH’s assistant commissioner for environmental risk assessment testified in a State assembly hearing held in late November.

Contaminants were not uniformly dispersed—so that one could find high levels of certain pollutants in one area and not in another.


But risk assessment was one of the biggest challenges for the various agencies because it was so difficult to accurately pinpoint the hazards in this instance. Several factors made it particularly difficult. The first was that equipment to monitor the air was not in place on September 11th.    That testing done in November and December may not have accurately portrayed the kinds of contaminants people were exposed to.

The Agency for Toxic Substances Disease Registry (ATSDR) of the Department of Health and Human Services (HHS), and the New York City Department of Health and Mental Hygiene, together collected air and dust samples from 30 residential buildings in November and December 2001 in lower Manhattan in an effort to gauge whether there were levels of contaminants in the dust to constitute a major hazard. But the agencies had to acknowledge that their conclusions might have been skewed because the dust they tested was already several months old.

“By November, outdoor dust contamination was likely reduced by wind, rain, and cleaning (city workers vacuumed the streets and sidewalks with HEPA trucks). Indoor settled surface dust may have been reduced if areas were cleaned before being sampled. Therefore, these results probably underestimate the levels of World Trade Center-related materials that were in lower Manhattan immediately after September 11,” they wrote.

 Setting up air monitors in New Jersey.
Photo: EPA (air monitors)

Plus, the contaminants were not uniformly dispersed—so that one could find high levels of certain pollutants in one area and not in another. They were heterogeneous, random mixtures of everything in the buildings—plastics from furniture, mercury from lightbulbs, including exotic metals like vanadium from computer parts.

The ATSDR wrote, for example, “A review of the building sampling results from this investigation indicates that there is not a consistent spatial distribution pattern of asbestos, SVF, mineral components of concrete, and mineral components of wallboard in air and settled surface dust. This indicates that the materials are heterogeneously distributed.”


A key problem was that the teams of people and the tools for environmental monitoring were not in place to respond to an event like that which happened. Shockingly, even though the high particulate count from the building collapses was higher than New York City had ever experienced in its history, the tragic event violated no pollution standards for particulate matter. 


That’s because the air quality regulations were set up to measure particulate matter loadings over 24 hour periods, rather than intense, short term bursts. Yet such a high-particulate storm, even lasting several hours, “can produce significant adverse health impacts,” wrote Eric Goldstein et. al. in the NRDC’s paper, “The Environmental Impacts of the World Trade Center Attacks.” Plus, these authors note, the same air standards did not adequately account for other health concerns arising from very fine particulate matter arising from the fires.


 “We in the environmental health community are used to high probability events with low probability risks,” says Paul Lioy, “the effects of ubiquitous, low level toxic substances, their probability of giving people cancer over a 70 year lifetime. We were not equipped to deal with a low probability event with high probability consequences.”