Airborne asbestos concentration from brake changing does not exceed permissible exposure limit

Area of Science:

• Occupational Health
• Environmental Science
• Industrial Hygiene

Background:

• Chrysotile asbestos was historically used in automotive brake systems, posing health risks to mechanics.
• Concerns persist regarding mechanic exposure to airborne asbestos during brake maintenance, particularly when using older methods.

Purpose of the Study:

• To quantify airborne asbestos fiber exposure levels for auto mechanics during routine brake maintenance.
• To assess the impact of specific brake maintenance tasks (filing, sanding, arc grinding) on asbestos exposure.
• To compare exposure levels against current occupational exposure limits.

Main Methods:

• Four vintage automobiles with drum brakes were used, fitted with new asbestos-containing brake shoes.
• Vehicles were driven approximately 2253 km before brake maintenance was performed under 1960s conditions.
• Personal and area air samples were collected and analyzed for fibers, asbestos, total dust, and respirable dust.

Main Results:

• Only chrysotile asbestos fibers were detected in the air samples; no other asbestos types were found.
• Airborne chrysotile asbestos fiber concentrations in all tests were below the established occupational exposure limit of 0.1 fiber/ml (8-hour time-weighted average).

Conclusions:

• Routine brake maintenance using chrysotile asbestos brake shoes, even with abrasive methods, resulted in exposures below current regulatory limits.
• While exposures were below limits in this study, continued vigilance and appropriate controls are recommended for mechanics working with asbestos-containing materials.