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NYC-WTC_000199082
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NYC 9/11 Public Portal Document
Mr. Bernard P. Orlan April 24, 2002 Air Sampling for Silica Page 2 1 P.S. 234M ATC Project No. 15-19125-0279
The OSHA Permissible Exposure Limit (PEL) is the only regulatory standard for silica exposure, however it is intended for occupational exposure in settings such as foundries, sandblasting, rock drilling, etc. The EPA does not have an ambient-air quality standard or guideline for silica.
The OSHA PEL for silica-containing dust is based on the percent of quartz (SiO2) found in the dust, the higher the percentage of quartz, the lower the PEL.
The formula for calculating the PEL is found in 29 CFR 1910.1000, Table Z-3. The formula is:
lOmg/m^ %SiO2 + 2
The PELS for the silica in these samples are shown in the table.
OSHA PELS for SILICA DETECTED March 26,2002
1st Floor Hall SI 13.0 26 0.0127 0.357 Cafeteria S2 16 32 0.0157 0.294 Room 211 S5 11 22 0.0135 0.417
The silica concentrations detected are all well below the OSHA PELs.
It is our pleasure to provide these indoor air consultative services to the New York City Board of Education. If you have any questions about this report, please contact me at (212) 353-8280, extension 212.
Sincerely, ATC Associates, Inc.
James R. Cohn, CIH, CSP Regional Manager Industrial Hygiene Division
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CITY_21MC100_003031230
NYC-WTC_000199083
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NYC-WTC_000199083Source: NYC Law Department, mirrored locally
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