Legal hold notice for WTC documents, undated

NYC 9/11 Public Portal Document

Are there air quality standardsfor Fine Airborne Particles in outdoor air? Yes. In 1997, the United States Environmental Protection Agency (EPA) recommended National Ambient Air Quality Standards for PM 2.5. National Ambient Air Standards are established to be protective of public health. The short-term standard (24-hour or daily average) for PM 2.5 is 65 micrograms per cubic meter (ug/m’). Generally, levels below the standard are considered to have a low risk of adverse health effects. The long-term standard (annual average) is 15 ug/m’. The short-term standard (24-hour or daily average) for PM 10 is 150 ug/m’ and the long-term standard (annual average) is 50 ug/m’.

Are you monitoringfor PM 2.5? Yes. The New York State Department of Environmental Conservation (NYS DEC) has had continuous (real-time) air particulate monitors (PM 2.5) collecting samples at eleven sites in New York City. These routine monitors are two on Staten Island, three in Manhattan, one in Brooklyn, three in Queens and two in the Bronx. The data from these monitors are evaluated daily. The Environmental Protection Agency is setting up additional monitors to collect particulate data (PM 2.5 and PM 10) in the community near the site.

What are the results ofthe PM 2.5 monitoring and how do they compare to the levels measured in air before September

Routine DEC air monitors: Beginning September 11* at 1:00 pm, the daily average standard of 65 ug/m3 for PM 2.5 has not been exceeded at any of the routine DEC monitoring locations. On most days since September 11, PM 2.5 levels at each of the monitoring sites have been similar to those measured earlier in September.

How do the monitoring data for PM2,5 compare to the standards? Routine DEC monitoring: As of September 26, the highest daily average level of PM 2.3 was measured at Public School 64 on September 13*. This school is at East 6* Street and Avenue B .d is the nearest routine monitoring site to the World Trade Center. The highest daily average at that location was 42.1 ug/m’, which does not exceed the EPA’s standard of 65 ug/m3. Daily averages of PM 2.5 at all the other routine sites were below 35 ug/m^.

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