Industrial hygiene elevated exposure notice, March 2002

NYC 9/11 Public Portal Document

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industrial hygiene elevated exposure notice Date: 03/14/2002

To>: Ray Master

CC: DDC- Bob Adams LMIG- John Rabovsky ATC- Mike Donovan a// A LMIG- IH File

From; Donald Weber

RE;: Elevated Exposures

Ray,

Attached are Elevated Air Sample Result Notifications for samples analyzed from 3/12/02 to 3/13/02. Elevated exposures are defined as above 50 % of the shift adjusted time weighted average (TWA) Occupational Exposure Limit (OEL) for the purpose of this notification.

These sample results are provided to you for distribution. You indicated that you will provide these to the contractor involved. The contractor affected were:

Nicholson

The following is a summary of the elevated exposure information that is attached:

• Elevated quartz concentrations as follows: ® 15833% and 512% of the shift adjusted OEL while drilling in WTC 6. These concentrations represent 158 times and 5 times the shift adjusted OEL.

• Elevated respirable dust concentrations as follows; • 667% of the shift adjusted OEL while drilling in WTC 6.

The higher exposure occurred with Drill DK 55. The lower of the two elevated exposures occurred with machine #87. Each worker wore respiratory protection in the form of NIOSH % mask respirators and P100 filters. It is important that proper use of respiratory protection be enforced until such time as is feasible controls are identified and can be implemented to reduce exposures to levels below the shift adjusted OEL. Repeat sampling is planned in an effort to further characterize this exposure. At this point, Full Face piece respirators with P100 filters could be made available to drill operators (voluntarily) pending additional sample results.

I am available to consult on controls for these operations.

3/14/2002 1

CITY_21MC100_002961420

NYC-WTC_000186582