Asbestos dust exposure during brake repair

Area of Science:

• Occupational Health
• Environmental Science
• Materials Science

Background:

• Chrysotile asbestos is used in friction materials, leading to potential exposure for automotive mechanics during brake repair.
• Approximately 300,000 mechanics in Germany may be exposed to asbestos dust from brake servicing annually.
• Understanding asbestos fiber concentrations is crucial for assessing and mitigating occupational health risks in this sector.

Purpose of the Study:

• To quantify asbestos fiber concentrations in the air during brake repair operations.
• To characterize the size distribution of asbestos fibers, particularly chrysotile, found in brake dust.
• To evaluate the cumulative asbestos exposure experienced by vehicle mechanics.

Main Methods:

• Field study involving 76 service stations and 90 dust measurements.
• Phase contrast microscopy and scanning transmission electron microscopy were used for fiber analysis.
• Personal air sampling and occupational history analysis were conducted on 210 vehicle mechanics.

Main Results:

• Extremely fine chrysotile fibers (<5 microns) were prevalent in brake drum dust, with longer fibers being rare (<1%).
• Short-term exposures during brake blowing and grinding reached 10^6 fibers/m³ for cars and 5-10x10^6 fibers/m³ for trucks/buses.
• Average cumulative asbestos exposure for mechanics was calculated at 0.54 x 10^6 fibers/m³-years over an average employment of 21 years.

Conclusions:

• Brake repair activities generate significant airborne asbestos concentrations, primarily composed of fine chrysotile fibers.
• Vehicle mechanics experience substantial cumulative asbestos exposure, highlighting a need for protective measures.
• The findings underscore the occupational health risks associated with asbestos in the automotive service industry.