Exposure to asbestos during brake maintenance of automotive vehicles by different methods

Our plain-English summary of Exposure to asbestos during brake maintenance of automotive vehicles by different methods, by T. Kauppinen, K. Korhonen (American Industrial Hygiene Association Journal, 1987).

The study

• Authors: T. Kauppinen, K. Korhonen
• Journal: American Industrial Hygiene Association Journal
• Published: 1987;48(5):499-504
• Cited by: 30 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000979).

Abstract

Asbestos concentrations were measured during the different operations of brake maintenance of passenger cars, trucks and buses in 24 Finnish workplaces. The estimated average asbestos exposure during the workday (8-hr time-weighted average) was 0.1-0.2 fibers/cm3 during brake repair of trucks or buses, and under 0.05 f/cm3 during repair of passenger car brakes when the background concentration was not included in the calculations. The background concentration was estimated to be less than 0.1 f/cm3. During brake maintenance of buses and trucks, heavy exposure, 0.3-125 (mean 56) f/cm3, was observed during machine grinding of new brake linings if local exhaust was not in use. Other short-term operations during which the concentration exceeded 1 f/cm3 were the cleaning of brakes with a brush, wet cloth or compressed air jet. During brake servicing of passenger cars, the concentration of asbestos exceeded 1 f/cm3 only during compressed air blowing without local exhaust. The different methods of decreasing the exposure and the risk of asbestos-related diseases among car mechanics are discussed.

In plain English

This study reported air measurements of asbestos taken during brake maintenance of passenger cars, trucks and buses in 24 Finnish workplaces between 1977 and 1983. The authors took measurements in 7 workplaces and collected the rest from existing measurement reports. Brake linings still often contained chrysotile asbestos. Fibers were counted by phase contrast microscopy. For trucks and buses, the highest levels came from machine grinding of new brake linings without local exhaust: 0.3-125 fibers per cubic centimetre (f/cm³), mean 56. Brushing, wiping with a wet cloth, and compressed air blowing with a vacuum funnel also gave mean levels above 1 f/cm³. For passenger cars, the mean exceeded 1 f/cm³ only during compressed air blowing without exhaust. Estimated 8-hour average exposures, not counting background levels, were usually 0.1-0.2 f/cm³ for truck or bus brake repair and under 0.05 f/cm³ for passenger car brakes. The authors noted that leaving out background could underestimate exposure. They concluded that grinding new linings may cause heavy exposure unless enclosure and ventilation are efficient, and that washing with water was the most preferable cleaning method.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Workplace exposure measurement survey (air sampling of asbestos fibers during brake maintenance operations, with estimated 8-hour time-weighted averages for hypothetical workdays)
• Who was studied: Car mechanics doing brake maintenance on passenger cars, trucks and buses in 24 Finnish workplaces, measured 1977-1983. The authors measured 7 workplaces themselves, and the other results came from measurement reports.
• Exposure: Airborne asbestos fibers released during brake maintenance operations (opening, brushing, compressed air blowing, wet cloth wiping, washing, grinding, riveting). The article describes brake linings and brake drum dust as containing chrysotile asbestos. Fibers longer than 5 μm, thinner than 3 μm, with aspect ratio over 3:1 were counted by phase contrast optical microscopy. Fiber type was not distinguished in the counts.
• Main results:
  • Trucks and buses: machine grinding of new brake linings without local exhaust gave 0.3-125 f/cm³ (mean 56), the highest concentrations measured.
  • Trucks and buses: other operations with mean concentration above 1 f/cm³ were brushing of brakes, cleaning with a wet cloth, compressed air blowing, and grinding of brake linings even with a vacuum funnel or local exhaust in use. All other operations had means under 1 f/cm³.
  • Passenger cars: mean concentration exceeded 1 f/cm³ only during compressed air blowing without exhaust.
  • Estimated 8-hour time-weighted average exposure, excluding background, was 0.1-0.2 f/cm³ during brake repair of trucks or buses and under 0.05 f/cm³ during repair of passenger car brakes.
  • The heaviest estimated workday exposure, about 7 f/cm³, was from grinding brake linings for 1 hour without exhaust.
  • Trucks and buses: the ACGIH limit for chrysotile (2 f/cm³) was exceeded only when new linings were ground without local exhaust. With all other procedures the estimated mean was less than 10% of that limit.
  • Background asbestos concentration in the workplaces was, at its highest, equal to the method's detection limit of 0.1 f/cm³. The 8-hour background was judged likely to be under 0.1 f/cm³.
  • Dust monitoring (tyndallometer) showed low levels during washing of brakes, and high peaks during brushing and compressed air blowing that usually fell back to background within 1-2 minutes.
  • Daily exposure during heavy-vehicle brake repair was on average 10-15 times higher than for passenger cars. Because the number of brake jobs per year differs, annual mean exposure was estimated to be only 3-5 times higher.
• The authors' conclusion: The authors concluded that grinding new brake linings may cause heavy exposure unless enclosure and local ventilation are efficient, and that washing with water was the most preferable way of cleaning brakes. They also suggested that the present exposures may indicate a lowered future risk of asbestosis, since past exposures were probably heavier.
• Limitations the authors state:
  • Background asbestos concentration was not included in the 8-hour estimates because few data were available, so the time-weighted averages may be underestimated.
  • The likelihood of asbestos-related disease from brake repair cannot be inferred accurately from these exposure data.
  • Vacuum brush cleaning was not measured because no workplace in the study used it.
  • The tyndallometer measured respirable dust, not asbestos specifically. The authors attribute the faster drop in concentration seen here than in other studies partly to this indirect method and lower starting levels.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Auto mechanics and brake work.

Medical terms in this study, explained in our Lexicon: Asbestos Exposure, Time-Weighted Average (TWA), Brake Lining.

Related studies

• Personal exposures to asbestos fibers during brake maintenance of passenger vehicles — M.F. Cely-García, M. Sánchez, et al. (2012)
• Asbestos exposure during brake lining maintenance and repair — A.N. Rohl, A.M. Langer, et al. (1976)
• An evaluation of short-term exposures of brake mechanics to asbestos during automotive and truck brake cleaning and machining activities — R.O. Richter, B.L. Finley, et al. (2009)
• Copper-enriched automotive brake wear particles perturb human alveolar cellular homeostasis — J.G.H. Parkin, L.S.N. Dean, et al. (2025)
• Mesothelioma in vehicle mechanics: is the risk different for Australians? — M.A. Kelsh, V.A. Craven, et al. (2007)
• Determining the frequency of asbestos use in automotive brakes from a fleet of on-road California vehicles — J. De Vita, S. Wall, et al. (2012)

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