Document yrxRqx6vn5r3Mn87bv8LDkvn6

MONTANA STATE BOARD 07 HEALTH Helena, Montana DIVISION OF DISEASE CONTROL A REPORT ON AN INDUSTRIAL HYGIENE STUDY * OF THE " V . ZONOLITE ccxpany _ ii:-: Libby, Montana April 11, 1963 Conducted fry: Benjamin-F. Wake Industrial Hygiene Engineer Division of Disease Control Distribution: This report is confidential and is not for distribution except to the management of the Zcnolite Company. On April 11, 1963 an Industrial Hygi ene Study vas made of the ZoDolite Company of Libby, Montana to deteruine the degree of conpliance of previous recosraendations to control the considerable dustiness in the dry sill section of the plant. The study vas made in the coapany of a representative of the Zonolite organization and vlth the assistance of Doctor Russel Hendricks, of the United States Public Health Service, Salt lake City, Utah. The methods of collection of samples and analysis of the various coaponents vere those recommended by the United States Public Health Service and other official agencies. The additional evaluation of the as bestos content of the dust Is currently being done by the United States Public Health Service, Occupational Health Division in Cincinnati, Ohio. The results of this evaluation vill not appear In this report but vill be reported upon as soon as the data is available. Descriotion of Operations Hie operation of the plant vas essentially that as described in previous reports and vill not be repeated here except to evaluate the over all dustiness on each floor and certain comments concerning dust producers at the locations noted. In general, there appeared to be little, if any, improvement at any point in the plant except perhaps at the voll grinder, vhere a significant reduction in dust contributed to this area has been accomplished. Specifically, the major dust-producing areas vere as follovs: - Fifth Floor - The screens vere very dusty. Ko apparent Improve ment had been made although the screen backs on most of the screens In this area vere In good condition. ' Fourth Floor -Much dustiness continues to be apparent In this area. The screen backs vere off some screens. Much dusti ness on the fourth floor contributes to the upper ----- floors. . Third Floor - The main dust producers in this area vere at number three concentrator bj.p and the belt transfer point to the concentrator bin. Dust leaks also at number tvo screv conveyer jind the high grade equipment in front of Ko. 3-2 screen. The Halfdeck -5This area vas extremely dirty, and the backs are off some of the screens. Second Floor -The duct to the high-gnde hammer mill had a hole in it, vasting exhaust capacity. Ko. 3I4 screen still leaked badly, and there vas no improvement in this area since last study. The tailing chute by the high- grade grizzley end near screen 3** vas also a consider able contributor to over-all dustiness. The feed to Ko. 219 belt vas a bad dust producer and should be en closed and ventilated. First Floor - Much dust vas produced at the high-grade dryer. Leaks from all pipes should be :*.opped and ventila- * tion applied vhere dust cannot be controlled by stopping. First Floor - The feed to belt 108 A vas extremely dusty and needs (Continued) ventilation and enclosure. The high-grade dryer vas _ . not operating during the last study and vas not ac counted for during that study but should be given con siderable attention. Ko. 6l8 elevator on the fourth floor leaked badly. There vas no excuse for these leaks except for poor operation. No. 336 elevator on the first floor also leaked dust badly. The cover sinply had not been completely replaced. The size distribution of the dust in the air as determined by the United States Public Health Service Indicates an average size of about 3.M* microns. It should be noted that these small- diameter particles can be de posited In the deep lung tissue and are more apt to be of physiological sig niflcance than those above 10 microns. In any case, over 60 percent of the particles were 5 microns or less, and 75 percent were less than 10 microns, all indicating a serious dust concentration, particularly in view of the quantity of asbestos known to be in the mixture. , * *.1: JVS-'- TABLE I Dust-in-Air Sample No. location and Description Concentration Asbestos Cone. in moocf* in mpp: 1 2 3 k __ 5 ?/ 3 6th Floor - Dry mill 5th Floor - Dry mill Itth Floor - Dry mill 3rd Floor - Dry mill 2nd Floor - Dry mill Halfdeck 2nd Floor Dry mill ,,- 1st Floor - Dry mill near high- grade furnice 1st Floor - Dry mill near main kilns Maximum Allowable Concentration 33.6 65.6 32.4 32.8 77.8 50.0 26.8 59.8 20.D 12.3 27.2 12.9 13.1 31.2 20.0 10.7 23.9 5.0 * Millions of particles per cubic foot of air. ** The asbestos concentrations are calculated on the basis of asbestos in the air-borr.e dust. - ***** Conclusions and Heccrr-.endations As noted in all previous reports, considerable effort should be made, imedietely, to improve the dust control procedures in the plant to reduce dustiness tc an acceptable level. .Any work cone in the past has apparently been ineffective to the extent that -ore effort should be given to this feeture than has been in the past. It hs hoped that in the next 60 days from the date of this report that suimcle ventilation will have been ecpLicd or dust control measures vill have: been applied such that the hazardous condition existing at this nlano if eliminated. PLAINTIFFS EXHIBIT /<?3 r&)