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NYC-WTC_000229425
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NYC 9/11 Public Portal Document
Mr. Bernard P. Orlan April 10, 2002 Air Sampling for Silica Page 2 Stuvvesant High School ATC Project No. 15-19125-0246
The formula for calculating the PEL is found in 29 CFR 1910.1000, Table Z-3. The formula is:
lOmg/m^ %SiO2 + 2
The amount of quartz in this sample was <24%, therefore the PEL for this dust would be:
lOmg/m^ = 0.385 mg/m^ 24 + 2
The silica concentration in this sample was 3.8% of the calculated PEL.
The OSHA 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 for silica.
Silica was not detected above the analytical limit of detection in any of the remaining samples collected on this date.
ATC appreciates the opportunity to provide this indoor air quality consultative service to the BOE. Please call me at (212) 353-8280 extension 212 if you have any questions.
Sincerely, ATC Associates, Inc.
James R. Cohn, CIH, CSP Regional Manager Industrial Hygiene Division
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CITY_21MC100_000492356 NYC-WTC_000229426
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NYC-WTC_000229426Source: NYC Law Department, mirrored locally
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