Document label for 10 Cortlandt Street

NYC 9/11 Public Portal Document

Hillmann Environmental Group. LLC

4.5 Respirable Dust

The American Conference of Governmental Industrial Hygienists (ACGIH) recommends a Threshold Limit Value (TLV) of 3.0 mg/m3 and the Occupational Safety and Health Administration (OSHA) has a Permissible Exposure Limit (PEL) of 5.0 mg/m Respirable dust levels ranged from 0.017 mg/m' to 0.66 mg/m3. Observed respirable dust levels were below the recommended limits in the building.

4.6 Total Dust

Dust and silica levels were measured in response to concerns of possible elevated levels due to the destruction of the World Trade Center and subsequent construction activities. Elevated levels of dust can lead to such irritations a scratchy eyes and throat, and dry cough. Samples were collected on both days of the investigation and analyzed for total dust present. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends that dust levels remain below 10 mg/m3, and silica levels remain below 0.05 mg/m3. The total dust amounts ranged from below the limit of detection to 0.083 mg/rrt3. Since levels of dust were in such low levels, silica could not be detected in any of the samples.

4.7 Mercury

Mercury is used in florescent light bulbs, electrical switches, thermostats, manometers, barometers, gauges, valves, and some doze alarm type alarm clocks, Mercury is also used in a number of industrial applications, such as fluid bearing and fluid clutches that require a heavy liquid. Mercury is a fairly unreactive metal and is highly resistant to corrosion. The health effects of mercury vapor can cause effects in the central and peripheral nervous systems, lungs, kidneys, skin and eyes in humans. It is also mutagenic and affects the immune system. The ACGIH TLV for mercury vapor is 0.025 mg/m3 as a TWA for a normal 1 0-hour workday and a 40-hour workweek and considers mercury vapor an A4 substance (not classifiable as a human carcinogen). NIOSH has established a recommended exposure limit (RET.) for mercury vapor of 0.05 mg/m3 as a TWA for up to a I 0-hour workday and a 40-hour workweek. In the subject space, mercury levels remained below the limit of detection of 0.001 mg/m3, and therefore below the recommended limit.

4.8 Polychlorinated Hiphenyls

PCBs are a class of industrial chemical that contains 209 individual compounds. PCBs are generally clear, colorless to light yellow, viscous liquids or solids with a mild hydrocarbon odor. They have a low vapor pressure and thus have a low volatility. The lowest recommended limit set by the National Institute of Occupational Safety and Health (NIOSH) for PCBs in air is 1.0 ug/m3. The USEPA screening level is 0.73 mg/m` Samples collected at selected locations throughout the building were below the limit of detection and below the level of concern for PCBs in air.

4.9 Volatile Organic Compounds

Volatile organic compounds are frequently used as cleaners and solvents. They produce vapors detectable at normal room temperature and pressure. Levels of volatile organic compounds measured by sample analysis ranged from 0.056 mg m to 0.67 mg/m3 in the subject space. Hillmann recommends a limit of 1.7 mg/m3 for these compounds. Levels of volatile organic compounds were below our recommended limit.

22 Cortlandl Street/New York, NY/Project Number Y2-1458 Page 22

NYC-WTC 000126283