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31-1 9-57 J
SHELL OIL COMPANY
EFFteNce
MARTINEZ - MARKETING NOR'PHERN CALIFORNIA AREA DISTRIBUTION MANAGER
SEPTEMBER 7. 1976
DATEE
INDUSTRIAL HYGIENIST -
FROM
DEPT. OF OCCUPATIONAL SAFETY AND HEALTH WALNUT CREEK
su,jectASBESTOS SURVEY BRAKE AND CLUTCH SERVICING OPERATIONS
Per request of Head Office Marketing, the airborne asbestos survey of the Northern California garage facilities during brake and clutch servicing of Shell trucks has been completed for San Jose Garage on June 9, 1976 and Sacramento Operations on June 17. There was no opportunity to conduct a similar survey at the Martinez Garage because brake and clutch repair operations occur very infrequently.
When repairing truck clutches and/or brakes, the mechanics at the San Jose and Sacramento Garages are not exposed to an asbestos health hazard. Airborne asbestos levels are well below the 2 fibers/cc 8-hour time-weighted average (TWA) exposure level and 10 fibers/cc ceiling exposure levels allowed by OSHA. Table I summarizes the mechanics' 8-hour TWA and ceiling exposure levels. The maximum 8-hour TWA observed was 0.03 fibers/cc while the highest ceiling exposure level approached 2.3 fibers/cc. These results agree with exposures reported in my March 1, 1976 report for brake and clutch repairs at the Los Angeles Centralized Garage. Additionally, these levels are also lower than the new proposed 8-hour TWA OSHA standard of 0.5 fibers/cc with its correspond ing 5 fibers/cc ceiling level.
While this survey has shown that there is no health hazard, the mechanics can be and are exposed to airborne concentrations of asbestos during certain activities. Consequently, certain steps are necessary to protect the mechanics' health and comply with current regulations. Accord ingly, I recommend:
Continued efforts to reduce or prevent airborne asbestos exposures during brake and clutch operations by cleaning techniques which preclude the creation of airborne asbestos. Cleaning of brake and clutch assemblies with a dampened rag is one preferred method instead of air or dry brush methods.
* Implementation of educational awareness programs alerting of the potential asbestos hazard in brake and clutch servicing operations.
ABS-038187
ASBESTOS SURVEY
SEPTEMBER 7, 1976
Completing the one-time initial survey at the Martinez Garage whenever the next brake and clutch servicing job is scheduled. This is necessary to comply with current OSHA regulations. The mechanic responsible for the scheduling should call this office at least one day before the job is to be done to permit sampling.
e Implementation of a medical surveillance program in accordance with guidelines from Head Office Marketing.
If this department can be of further assistance, please contact Hank McDermott.
S. E. KilUany, Jr.
Attachment
cc w/a:
Head Office - DOSH - Staff Industrial Hygienist Head Office - Corporate Medical Director Martinez - Mktg. - N. Calif. Facilities Manager Head Office - Mktg. - Employee Safety Manager
ABS-038188
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ABS-038189
ATTACHMENT II: ASBESTOS SURVEY BRAKE AND CLUTCH SERVICING OPERATIONS LOS ANGELES MARKETING CENTRALIZED GARAGE
On September 24, 1975 and February 3, 1976 breathing zone air samples were collected at the Los Angeles centralized garage to determine the mechanics' exposure to asbestos while repairing delivery truck clutches and brakes. Air samples were collected during replacement of two clutches and brake linings on three separate wheel units. The mechanics cleaned the clutch housings either by air blown with a pressurized hose, or wiping with a wet rag. Brake shoes, including the wheel units, were steam cleaned. New clutches and brake plates are supplied by contract with an outside supplier who does the necessary fitting and grinding of the brake plates or clutch assemblies at their own shop; the mechanics at the L.A. centralized garage do not grind or arc linings.
Routinely, clutch and brakes are adjusted daily, but not necessarily replaced. Clutch replacements occur on an as need basis and are infrequent. Brake replacements may occur on the average of one axle (two wheel units) per month, with the maximum being two axles (four wheel units) a month.
Mechanics at the Los Angeles centralized garage are not exposed to any health hazard of asbestos. The 10-hour time weighted average (TWA) asbestos exposure is 0.02 fibers/cc or less on days that the mechanics service the truck's clutch or brakes. Asbestos exposure from brake servicing activities is lower than for clutch repairs. This is true because
ABS-038190
^vENT II
2
linings are not enclosed in a housing or drum but are open to the atmosphere and any dust that is created from the frictional rubbing of the lining falls out on the roadside as the truck moves along the highway. Exposures to asbestos dust from the clutch servicing operation can approach ceiling concentrations of 2.0 fibers/cc when the mechanic wipes the housing with a dampened rag and dry sweeps the dust residue from the floor with a pan and hand broom. Blowing the housing with air resulted in a ceiling asbestos exposure of 1.3 fibers/cc. Table II-1 summarizes the 10-hour time weighted average exposures on the days when the mechanics service a truck clutch and/or brake linings. Table II-2 summarizes maximum observed airborne asbestos concentrations for different operations such as cleaning the clutch housing, removing the wheels to service the brakes, etc.
Rec ommendations
While the mechanics at this garage are not exposed to^ny asbestos health hazards, finite levels of asbestos have been identified with certain activities. In conjunction with current regulations and the recent NIOSH asbestos alert for brake and clutch operations, I recommend the following:
To reduce or prevent airborne asbestos concentrations during brake and clutch' servicing operations and minimize the mechanics' exposure, - the residual dust from these operations must be cleaned by methods which preclude the creation of airborne
ABS-038191
xlENT II
3
asbestos concentrations. Brake shoes, brake and clutch assemblies and housing must be cleaned by wiping with a wet rag or by a high efficiency industrial vacuum cleaner. The truck wheel units can be steam cleaned. The use of air or dry brush cleaning methods must not be used for cleaning the residual dust occuring in these brake and clutch assemblies or on the floor after the clutch is removed from its housing.
whenever possible, mechanics should be rotated on these type of servicing operations. Currently, the mechanics at the Los Angeles centralized garage are assigned to these tasks on a rotational basis.
an educational awareness program alerting of the potential asbestos hazard in brake and clutch operations, should be incorporated into the mechanics training programs and courses.
Finally, to comply with current regulations, an initial monitoring and a medical surveillance program as suggested in the retail salary service station survey should be considered for the other Shell truck maintenance garages.
ABS-038192
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