Document YrrMNgKq4QXnLw0QOdgZJLJ0K

1. u AKERICAK 8MSLTIN0 AND REFINING COMPANY Department of Hygiene Balt Lake 0ity, Utah ! RECEIVED February 2*, 1965 Utt 1 '65 TO / EiU / ( ANED Mr. 2. A* Farrell Lake Aebeatoe of Quebeo ?. 0. Box 127 South Plainfield, New Jersey !____Eif_____ _______ Dear Edi In your letter of February 15 you requeited Information for V; R. Qreee Co. on* 1. "Maximum duet level permitted in different tatea and Industries or referenoea." Most of the states have adopted the Halt recommended by the Anerloan Conference of Governmental Industrial Hygienists, a quasi* official group vhloh has assumed leadership In establishing safe limits for many air contaminants. The ACQZH Halt for asbestos dust is 5 million particles per oublo foot of air for o*hour, continuous, dally exposures. The limit applies to samples oolleeted with the Oreenburg-Smltb Implnger, or by a comparable method, and oounted by light field microscopy. A eomplete discussion of dust sample collection and evaluation la given in "Industrial Dust" by Drinker and Hatch, published by McOraw-Hlll, and in "Industrial Hygiene and Toxioology," Volume I, published by Zntersolenee Publishers, New York. 2. "Data and rafertnoas on orltleal partiole alee." There Is some o ontroveray over the relative dangers of small particles (abort fibers under 5 microns In length) and long fiber* of 10 miorone or more. Long fibers may provoke a fibrous reaotlon in lung tie bus .somewhat more than short fibers. But long fibers In the air have a lesser ohanoe of getting down deeply into this lungs because of entrapment In the upper respiratory system. So tbs relative dangers of email and large particles tend to belenoe out. JRN ?. *91' 7:03 EFS 0000031 * 20153B40BB PAGE.017 l I * *vp * * I I .rurvtiw onuMocnb & hc"6&4 631 3100 \ .su Hr. E. A. Farrell Page 2 A comprehensive discussion of dust particle tlse and Ita aignifioanoe la glvan in "Pulmonary Deposition and Retention of Inhaled Aerosols" by Eatoh and Oross, Aeademlo Press, Hew York, 196s. 5. "Recommendation on hov to measure duet level equipment and prooedure." Although the original Qreenburg-Smith iaplnger method of duat campling la reoognlaed aa standard, it has been shown that sampling with properly calibrated midget impIngeref portable eleotroetatlc precipitators and membrane (Hllllpore) filter! will give comparable results. She important part of the dust measurement la the eountlng - by light field with a 16 mm objective and IOOC eyepiece and a proper eountlng eell. Counting Is an exaoting and tedious prooedure. 4. "Mask and filler recommendation." Any respirator and filter oomblnatlon approved by the U. 6. Bureau of Minea for protection against pneumoconloals-produolng dusts will provide satis factory proteotlon. The reaplrator abould ba fitted carefully to each individual. Xf one brand does not fit snugly, another should be tried. The leading manufacturers of respiratory protective` equipment are Mine Safety Appllanoea Company, American Optical Company, and Villaon Produota. 5. "References on Rational and State regulations related to asbestos and Its produota." The only regulations of mhloh X aa aware relate en tirely to the workroom air dust levels in the produotlon of asbestos and in the fabrication and use of asbestos produots. Some alarmists have raised the question of publlo health and asbestos dust levels in the air over streets and highways. X doubt that auch cries of alarm will be taken very seriously. First, there Is no credible vldenoe that there is any real health hazard to the general publlo. Beoond, In a mixed dust exposure euch as all of us have on a busy street, the identification of asbestos dust, among all the different types of dust present, beoomes prectioelly Impossible. JAN 7 9 | 7: 04 EF8 0000032 2015364006 PA6E.018 r\, Mr. E. A. Farrell Page 5 Attached is ft Hygienic Oulde on asbestos published by the American Industrial Hygiene Association. Z suggest that the Ouide sight be ueeful in answering routine inquiries about aabeatoi dust. Additional oopiea Bay be ordered fro AXHA, 14125 Prevost, Detroit. Very truly, yours, KWR/nb End. cot K. R. St J>, Meesel (no VillieBS^ er nel) L. Riabault ) R. P. Qagnon I L. C. Pluse / A. St Phillips V. P. Roe R. 0. Crane C. S. Stleflcen D. H. Soutar Dr. Pinto JAN ? '91 7 s 04 EFS 0000033 ' 20153B400B PPGE.019