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The U.S. Environmental Protection Agency (EPA) and other federal, state and local agencies have collected extensive environmental monitoring data from the World Trade Center site and nearby areas in Manhattan, Brooklyn and New Jersey. Since September 11, EPA has taken samples of the air, dust, water, river sediments and drinking water and analyzed them for the presence of pollutants that might pose a health risk to response workers at the World Trade Center site and the public. The samples are evaluated against a variety of benchmarks, standards and guidelines established to protect public health under various conditions. EPA is collecting data from more than 20 fixed air monitors in and around ground zero and additional monitors in the Bronx, Brooklyn, Queens and Staten Island. The Agency is also using portable sampling equipment to collect data from a range of locations.
Air: Fixed Monitors in New Jersey:
Asbestos - Twelve air samples were taken in New Jersey on October 25, 26 and 28 (4 each day). All samples showed results less than 70 structures per millimeter squared, which is the Asbestos Hazard Emergency Response Act (AHERA) standard for allowing children to re-enter school buildings after asbestos removal activities. This brings the total number of samples collected and analyzed in New Jersey to 173, with zero above the standard.
Staten Island Landfill:
Air (Asbestos) - Nineteen samples were collected from October 29 through October 30. All the samples showed results less than the school re-entry standard.
Ambient Air Sampling:
VOCs - One grab sample collected on September 19 from the center of the debris pile at the World Trade Center was analyzed for volatile organic compounds (VOCs). To protect workers at the work site, EPA takes grab samples of VOCs where smoke plumes have been sighted. The results are snapshots of the levels at a moment in time. OSHA's protective standards set a permissible exposure limit (PEL) averaged over an 8-hour day. The results showed benzene levels of 4.6 parts per million (ppm), which exceeds the OSHA PEL of 1 ppm.
Sampling for VOCs was also conducted on October 30 in the direct area of the debris pile at ground zero. Benzene exceeded the OSHA permissible exposure limit at one location (North Tower) at ground level on the debris pile in the plume. Two of the three samples (Austin Tobin Plaza and North Park Pier) did not detect any benzene levels above the detection limit of 20 parts per billion by volume (ppbv). Chlorodifluoromethane (Freon-22) was detected and confirmed in the North Tower debris pile (660 ppbv) at ground level, but was well below the National Institute of Occupational Safety and Health (NIOSH) recommended exposure level of 1000 ppm.
VOC samples collected on October 31 from the debris pile of the South Tower at ground level showed benzene levels that exceeded 1 ppm. Samples collected at Austin Tobin Plaza and North Park Pier did not detect levels of benzene above the detection limit of 20 ppbv. Freon-22 was detected and confirmed in the North Tower debris pile (39 ppbv) at ground level, which is well below the NIOSH recommended exposure limit of 1000 ppm.
PM 2.5 - Monitoring for fine particulate matter (particles less than 2.5 micrometers in diameter) was conducted October 30 at Pace University, the Borough of Manhattan Community College, and the U.S. Coast Guard building located in Battery Park. All 24-hour averages were below the National Ambient Air Quality Standards (NAAQS) of 65 micrograms per cubic meters (ug/m3)) for all stations. These results were also less than 40 ug/m3, a level on the EPA Air Quality Index, which would indicate the air quality is unhealthy for sensitive populations (e.g., those with respiratory illnesses).
Direct Air Readings - Using portable monitors, direct air readings were taken in and around ground zero on October 30. Results showed several readings above the carbon monoxide NAAQS (8-hour average) of 9 parts per million (ppm), but was below the NAAQS (1-hour average) of 35 ppm and the OSHA PEL of 50 ppm. Direct readings taken on October 31 showed nothing of significance.
Metals - Ten wipe samples were collected on September 29 at Public School 234 and analyzed for metals. Lead results were all below EPA's Title X criteria of 40 micrograms per square foot (ug/ft2). While no specific standards are available, all other metals were either not detected or present at low levels.
PCBs - The recent analysis of four dust samples, which were originally collected from the streets around ground zero on September 11, showed results below the EPA residential cleanup guideline level of 1 ppm for PCBs.
Semi-Volatile Organic Compounds - The recent analysis of dust samples, which were originally collected from the streets around ground zero on September 11, showed results for benzo(a)pyrene below EPA removal action guidance levels, which are based on a 30-year exposure.
U.S. Government Website