Memo draft for DEP Commissioner, Oct 2001

NYC 9/11 Public Portal Document

Air Sampling Qualified individuals who possess valid certification must perform the air sampling for asbestos. The air samples can be collected for analysis by phase contrast microscopy (PCM) and/or transmission electron microscopy (TEM). Both types of samples are collected by drawing air through a filter at a set flow rate for a specific period of time. The filters are then sent to a laboratory for analysis.

PCM analysis measures all fibers trapped on the filter that meet the National Institute of Occupational Safety and Health definiti n for a fiber. The results can therefore include asbestos and non-asbestos fibers (such as carpet and fabric fibers). The PCM samples are easier to prepare and tike less time to analyze. The results are reported in fibers per cubic centimeter (free) and are compared to the strictest USEPA, NYS DOL, and NYC DEP clearance or re-occupancy standard of 0.01 free. The worker exposure standard set by OSHA is 0.1 free for an 8-hour time weighted average.

TEM analysis is available from fewer laboratories and takes longer to prepare, but provides specific information as to the amount and type of asbestos present on the filter. The results are reported in structures per square millimeter and are compared to the strictest USEPA AHERA standaid of 70 s/mm^. This standard is the USEPA re­ occupancy criteria for children to reenter a school after asbestos abatement.

Water Sampling

The NYCDEP increased water sampling in lower Manhattan after September 11, 2001. The water samples have not indicated pollutant levels above the clean water standards set by the USEPA.

The NYCDEP daily monitoring for asbestos in the outdoor air has disclosed a few sites in the immediate vicinity of the World Trade Center with levels above the clearance levels. These results have been followed up with additional continuous sampling and follow-up with TEM analysis. Results obtained within the past few days indicate that levels are below the clearance levels. The USEPA based the level of concern on continuous exposure for an extended period of time and expects that clean up efforts will continue to reduce asbestos levels dramatically over the next several weeks.

According to NYC DOH statements, the ongoing monitoring of airborne contaminants indicate that the levels continue to be below the levels of concern to public health and do not pose long-term health risks to the general public. Significant quantities of smoke and dust were released following the collapse of the WTC Towers. In the days following, smoke varied depending on the weather conditions. The smoke can cause throat and eye irritation. The symptoms should diminish as exposure decreases. Air particulate monitors have been collecting continuous samples at eleven sites in New York City. The samples have not exceeded the USEPA standards. Further, as ex’^ected, asbestos is present in some of the debris at the site and in the areas very close to the site. However, most air sampling results were below the standards.

In addition to the daily air monitoring activities, a dust protection and suppression plan has been developed for the search/rescue, demolition, and clean up of the World Trade Center site. The USEPA posts daily results on their web page at epa.gov. The NYCDEP posts daily results at nvc.gov. This site also contains various fact sheets.

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