Document x1QbOy2ko3moGKbj0RVV752Km

AMERICAN 8MELTXN0 AND REFINING COMPANY Department of Hygiene Salt Lake City, Utah * RECEIVED February 2k, 1965 Mr. S. A. Farrell Lake Aebeatoe of Quebeo P. O. Box 127 South Plainfield, New Jersey --E F---------- --**--------- <---------- Dear Edi Za your letter of February 15 you requested Information for V. X. Qrsee Co. oni 1. "Maximum dust level permitted in different states and industries or references." Most of the states have adopted the limit recommended by the Aaerloan Conference of Governmental Industrial Hygienists, a quae In official group which has assumed leadership In establishing safe limits for many air contaminants. As ACQXH limit for asbestos dust is 5 million particles per eublo foot of air for o*hour, continuous, dally exposures. The limit applies to samples collected with the Oreenburg-Smlth implnger, or by a oooparable method, and oounted by light field microscopy. A oomplete discussion of dust cample collection and evaluation is given in "Industrial Dust" by Drinker and Hatch, published by McOraw-Hlll, and In "Industrial Hygiene and Toxloology," Volume I, published by Zntersolenee Publishers, Mew York. 2. "Data and references on oritleal particle aixe." There la some controversy over the relative dangers of small particles (short fibers under 5 microns in length) and long fibers of 10 mloraas or more. - Long fibers may provoke a fibrous reaction in lung tissue .somewhat more than short fibers. But long fibers in the air have a lesser ohanoe of getting down deeply into the lungs because of entrapment in the upper respiratory system. 8o the relative dangers of small and large particles tend to balsnoe out. JAN 7 '91 7:03 EFS 000003 J 2015384005 PAGE.017 s\b *A I ( t l "0 . }m onunocnlj 6 hc-*6&* 631 3100 \ C ;*u Mr. Z. A. Jarrell Page 2 A comprehensive dlacuBtlon of dust particle fixe and lte algnlfioanoa is given in "Pulmonary Deposition and Retention of Inhaled Aeroeola" by Eatoh and Qroaa# Aeademio Preaa, Mew York, 1964. 3. "Recommendation on how to measure duet level equipment and procedure." Although the original flreenburg-Smlth impinger method of duat aampllng la recognised aa standard. It has been shown that sampling with properly oslihratsd midget lapingera, portable electrostatic precipitators and membrane (Mllllpore) filters will give comparable results. She important part of the dust measurement is the counting - by light field with a 16 ami objective and 10K eyepiece and a proper counting oell. Counting is an exacting end tedioue procedure* -- 4. "Mask and filler recommendation." Any respirator and filter combination approved by the U. 6. Bureau of Mines for protection against pneumoeoniosis-produoing dusts will provide satis factory protection. She reapiretor should be ' fitted carefully to caeh individual. If one brand does not fit snugly, another ehould be triad. The leading manufacturers of respiratory protective' equipment are Mins Safsty Applitnoes Company, American Optical Company, and Villa on Products. 5* "Referenoea on Rational and Stats regulations related to asbestos and lta produots." The only regulations of whioh I am aware relata en tirely to the workroom air dust levals In the production of asbestos and in the fabrication and use of aibsstoi products. 800s alarmists have raised the question of publlo health and asbestos dust levels in the air over streets and highways. 2 doubt that sueh cries of alarm will be taken very seriously, Jirst, there is no credible evidenoe that there is any real health hasard to the general publlo. Beoond, in a mixed dust expobure such as all of us have on a busy street, the Identification of asbestos dust, among all the different types of dust present, beoomea practically Impossible. JAN 7 '91 7:04 EFS 0000032 20I530400B PAGE.019  SV .1 Nr. E. A. Farrell Page 5 Attached la a Hygienic Ouide on asbestos publlahed by the Aaerican Industrial Hygiene Aaaoclatlon. I auggeat that the Ouide night be useful in answering routine inquiries about asbestos dust. Additional ooples may be ordered froo AXHA, 14125 Prevoat, Detroit. Very truly, yours, lCKR/ab 2nd. fcci M. J. Mescal (no end) R. . VilllBBS-^ L.Rlabeult R. F. Qagnon )f L# Ci Pluse A. JPhillips V. P.Roe R. QiCrane C. S. Stlefken D. H. 8outer fir. Pinto JAN 7 '91 7:04 EFS 0000033 ' 20153B400B PAGE.01S