Document 6BB74MErb5me5op8bnGrwJNXo

Abt Associates, Inc. Page 37 -3- December 28, 1977 The draft states that the first operation In brake maintenance shops which Is "known to produce dangerous levels of asbestos dust In the air" Is "blowing out brake drums with compressed air. This Is the chief hazard In automobile brake shops." There Is a question as to whether the decomposition products of used brake linings are the chief hazards In automobile brake shops. While this may be the case, I do not believe that It has been established that dust from the decomposition products of brake linings blown out with compressed air Is the dangerous form of asbestos dust in the workplace. It Is more likely that grind ing, chamfering, drilling and cutting of new brake materials may be a more serious problem as regards producing respirable asbestos dust which would be the known dangerous asbestos product in the workplace. r Further the draft indicates that other dangerous operations are the grinding of used truck brake linings and the beveling of new truck brake linings. These ' questionable conclusions from a non-typlcal shop are apparently the result of relying on the Rohl report of operations in a truck shop. My observation Is that very few automobile brake shops bevel (or chamfer) new truck brake linings. Most do not even work on truck brake linings. There may be more problems with grinding drilling and chamfering (bevelling) operations In a shop which feels that they have to adapt materials to fit particular brakes. As indicated most lined brake shoes are usually ready for installation without additional machining, and this p rocedure should be recommended. It might also be commented that with the author's emphasis on blowing out of brake drums and grinding and bevelling brake linings, and with Illustrations always showing drum brake linings, that the new and now common disc brake linings have not been mentioned. Obviously disc brake linings are widely used and are on over 50X of the brakes on new cars today. The only drum brake linings are on the rears. In many cases these drum brake linings are not relined as often as the disc brake linings. I agree that blowing out brake drums with compressed air Is not a good practice and should be discontinued. I do not believe that it has been established that this is the chief hazard In automobile brake shops. The wording should refer toblowing out "brakes" with compressed air. Most times the mechanics take the air hose directly over to the vehicle with disc or drum brakes and blew out the dust from around the caliper or cylinders before proceeding with the reline. (This is indicated in slide 12). I believe that Illustrations and comments should be made of disc brakes as well as drum brakes so that this guide will not he considered a publication of the 1960's. . Pages 32. 34. 36. 64 Illustrations on these pages show a technician taking a sample of asbestos holding a probe or collector. Samples are not taken In this fashion. A sample la norm ally taken with the worker wearing the sample collector in a fashion that would be equivalent to his breathing the air at his work station. . FMSl 03333 T Aht Associates, Inc. Page 42 4- - December 26, 1977 Again the illustrations are for brake drums or lining for drum type brakes. It . might be well to have an illustration of someone standing and vacuuming the dust from the disc brake assembly on the car. Page 43 Again it is stated that the worst offender among brake shop operations is blowing the dust out of drums. I agree that this is a common practice that should b discontinued. However, the wording should also refer to disc brakes and my comments on page 37 still apply. There is another item on page 43 which I question. The draft states that brake linings also contain silica which can cause lung disease and lead which harms the nervous system. The sentence is not correct because brake linings do not necessarily contain silica or lead. While it is true that some brake linings may contain silica and some may contain lead it is most likely that the majority of brake linings commercially used today do not use either silica or lead. Page 45 The draft states: "Do not use for cleaning brake drums, surfaces, or equipment." It is referring to compressed air nozzles. Again, the specifying of "brake drums" is not proper because mechanics not only use compressed air for blowing out disc brake assemblies but they also use it for blowing out the backing plate assemblies on drum brakes. If such a label is to be used it should read "Do not use for blow ing out dust from brakes, drums, discs, rotors or calipers," or some other word ing to this effect. Page 47 Again the draft states: "The first thing the workers should learn is the proper way to clean out brake drums." Again, the emphasis is on brake drums which are now being superseded by disc brakes. It might also be suggested that shops could remove the dust from brake drums by taking them directly to a workbench and tapping out dust on old newspaper which could then be wrapped and put in disposable plastic bags. This would be prior to the washing out with a wet rag. Page 65 The draft states that the monitoring tests must be done at least every six months. It is my understanding that the monitoring should be done at least every six months where asbestos concentrations can be expected to exceed the 2 fibers per cc limit. If experience in earlier monitoring and in the introduction of good work practices indicates that the concentrations would not be above 2 fibers per cc, I question whether monitoring must be done "at least every six months." FNIS1 03334