Document N23ERVeBbpYYRKDa7xn2n7NvD

i* RMk Wl 0- I* Public Health Service UNITED STATES GOVERNMENT Memorandum NOTE: TV uc r\ r' ` ' ^ ''i 1 to ; Chief, EngineeidLng Section i v/ ; . date: August 21, I963 fkom : Engineering Section subject: Asbestos Dust Sampling Procedures Work involving methods of sampling for chrysotile asbestos dust at the Jefferson Lake Asbestos Corporation, Coppercpolis, California, left much doubt as to the effectiveness of the impinger for fiber collection. Many problems arise when the Standard Impinger Method is used. Some of these problems are: 1. Difficulty in obtaining complete settling of all asbestos fibers in a counting cell. 2. Inability to see fibers with light field illumination. 3. Strong possibility that fibers are "broken up0 upon im pingement. U* Questions regarding the efficiency of the impinger for collecting fibers. 5* Apparent incongruity between the present Threshold Limit Value for asbestos environments and actual asbestos fiber concentration. The activity at the Jefferson Lake plant involved a new technique using opaque filter papers for the sampling of asbestos. Also, samples were obtained so that an estimate of impinger effectiveness could be obtained. On Juno 10, 1963 samples were taken simultaneously with a Greenburg-Sraith Impinger and an Electrostatic Precipitator. The collecting media used in the impinger was a 25a ethyl alcohol75a distilled water mixture. This same mixture was used to wash down the precipitator tubes. After'careful mixing, slides wen prepared from each solution by evaporating solution drops and leaving aresidue. Each slide was then sized measuring the horizontal pro jection or Martin*s Diameter of each dust particle. No distinction wa3 made between grains and fibers. light field illumination with a U3X objective lens and a 101 eyepiece lens were used. The ob jective lens has a numerical aperture of 0.65* The results were: ^* THIS DOCUMENT WAS NOT A RECORD OF PPG INDUSTRIES, INC. DID NOT COME FROM IT'S FILES AND CANNOT EE AUTHENTICATED BY PPG INDUSTRIES, INC. 3428 2 NOTE:- - T1 J 5- Vi, i< O 71' H ^ t ',, . ;f -- 8/21/6^ ^ ] Chief, Engineerin g Section ^ 'I T 1 i *., Sample No. 1 2 3 h 5 6 7 8 9 10 Air Vol. U.S. ks? G.S. Impinger Cone, (mppcf) 5 ft3 15 ft3 35.0 m m 1*6.0 n 33.0 i / 2iu5 ft V 30.6 V 35.1* n a 33.2 ft * 28.3 w ft 35J* n a 36.2 G.S Hg-p .81* 3.99 ESP i 1.29 'cr - ir 3.1 .93 3.89 1.32 3.8 .91* 3-79 1.30 3-16 .90 i 1.00 3.78 1.23 3.25 1.30 3.08 2.81 .98 2.6 1.1*3 3.28 1.02 3.3 1.21 3.82 .96 3.01* 1.39 3a .09 3-1*8 1.33 3.0 1.00 3.02 lJi2 3.52 11though the recults of this sizing are quite consistent, not enough specific information about the asbestos in the samples was obtained. By visual estimate between 5% and 8^ of the dust was asbestos fiber . the rest of the particulate matter in the sample being antigorit and other gangue material. A closer look was taken at each sample. Each slide was sized using the following procedure: 1. All non-fibrous material was sized using Martini Diameter as the significant length. .2. All fibers were sized by the measurement of the length dimen sion - regardless of orientation. 3. A tabulation was made in which both asbestos fiber and gangue material were logged. U. A fiber was defined as anything which appeared to be asbestos. 'CTi'opJllllJ. THIS DOCUMENT WAS NOT A RECORD OF PPG INDUSTRIES, INC. DID NOT COME FROM IT'S FILES AND CANNOT BE AUTHENTICA1 ED BY PPG INDUSTRIES, INC. 3423 " i - 3 - NOTE: THIC I--'"0'* NOT f,0i'.;2 r;-0,,,' i ) \ Chief, Engineering Section -- 8/21/63 5* Phase contrast with a U3K objective lens and a 101 eyepiece lens. 6. KooiG-er' illumination was used. The numerical aperature of ih objective lens is 0.65. The results of this sizing effort were: iamplc No. 1 2 ESP Mg-p tr 1.88 3.03 2.00 2.7k G.S. Impinger >ig-p <T 1.08 3.33 1.12 3.12 3 1.82 2.72 1.06 3.30 k 5 .6 1.35 l.Gh 1.83 3.30 2.82 2.78 1.13 1.08 1.09 3.23 2.96 2.76 7 1.81 2.8U 1.11 3.00 8t 9 10 1.76 1.83 1.9k 3.27 3.33 3.10 1-13 1.10 1.12 3.10 2.96 3.0U The Grcenburg-Sraith Ijnpingcr samples had a greater number of particl s equivalent to a circle number ono than the Electrostatic Precipitator samples. About $0% of the particles were "ones" in the Greenberg- Smith while about 29% of the particles in the ESP were "onesNo "one" circle size particles could accurately be identified as asbestos. In the ESP samples 27% of the dust sized was identified as asbestos. Tho G.S. impinger samples contained 162 asbestos fiber content of all particles sized. It is interesting to note the much higher percentage of asbestos identified during the second sizing tabulation - indicating that phase contrast bettor delineates the asbestos fibers. It is also interesting to note that all dust identified as asbestos had a length to diameter ratio of at least 3:1. . ] BB 00 2093 8__ THIS DOCUMENT WAS NOT A RECORD OF PPG INDUSTRIES, INC. DID NOT COME FROM IT'S FILES AND CANNOT BE AUTHENTICATED PY PPG INDUSTRIES, INC. 3430 NOTE: T' Chief, Engineering Section -- 8/21/63 :i The tabulation of the 1 articulate in all ten samples identified as asbestos gave the following results: Rg-h KSP_______` ______ CT (upper) Tj (lower) _________ G.5. Impinger Mg-p ^ (upper) ^(lower) 2.9 2.78 1.85 2.17 3.01 1.55 The asbestos fibers do not give the characteristic "straight line" on log-probabi] ity paper win ch describes the size distribution of so many mineral dusts. Instead, a gently sloping curve is the result. In this case a better description of the curve shape is obtained when a standard deviation is defined for both the upper and lower portions of the curve. Since a marked difference was noted in the geometric mean of the Greenburg-Smith and EEP samples taken simultaneously ia a concentra tion where the asbestos was the minority dust, it was desired to ob tain. data where the asbestos was in the majority. A cloud of chrysotilc. was generated by a dry method in the dust chamber. The airborne dust can be favorably compared with industrial asbestos dust encountered in working environments. Five runs were made. Simultaneous samples were taken with the Greenburg-Smith Impinger, tile Midget Imjlinger, and the Electrostatic Precipitator. Eie sampl ing time was five minutes. The linpinger concentrations were; Greenburg-Smith Inpihger Midget Impinger No. HPPCF MP1UF % Fibers mPpcf MPFCF % Fibers Grains Fibers Grains Fibers A B' C D 6.3 7.3 9M 6.3 5.6 13.2 7.7 8.2 1.1 1.2 67.6 70.0 16.6 11.2 12.8 22.6 11.1 15.3 10.2 9.1 15.3 10.1 5.8 . 9*1 6.2 ,31 Ji 38.0 37-8 5.6 37.8 7*BB*00 209l2J. -o iU . is. document was not a record of G INDUSTRIES, INC. DID NOT COM - FTOM S FILES AND CANNOT BE AU i, 0 ' PPG INDUSTRIES, INC. 34% ro a CD ND * 14, L / J NOTE: THIS ?OCP` - 5 - NOT CO ' r. i 1 tWi73 Chief, Engineering Section -- 8/21/63 "* ij ) { ) r\1 \ -J j* i L C The samples were tai:cn with an ethyl alcohol-water mixture consist ing of approximately 25/ ethyl alcohol. The sampling time was five minutes. The samples were counted. In Dunn cells after a settling period of >0 minutes. The samples were counted using 1QX phase contrast objective and 10X eyepiece. In addition the ESP tubes were washed down with the ethyl alcoholwater mixture and slides were prepared from these tubes and the impingera by evaporating drops and leaving dust residues on the slides. Each slide was then sized using a U3X phase contrast ob jective with a numerical aperture of 0.65 and a 10X eyepiece. Any particulate matter was sized according to Hartin1 a Diameter while all asbestos fiber was measured according to length. A.separate tabulation of asbestos fibers was recorded. The results of the sizing ore as follows: Sample __ px.S^ Twninp.fr_____ Midret Tmninrer Wo. Mg-p <4 % Mg-p. asbestos Hg-p. asbestos ESP % asbestos `A 1.5 2.83 56 1.97 3.U8 63 3.29 2.53 69 B 1.63 60 1.77 3-la 61 3.03 3.03 7U C 1.63 2.30 59 1.93 3d8 61 3.lit 2.80 77 D 1.SU 2.1*7 62 1.90 2.8U 60 2.88 3.36 72 St CM E 1.62 61 1.98 3.28 60 3.05 2.66 7U None of the dust equivalent to a "one* circle size could be classified asbestos or non-asbestos, The percentage of "One" circle sizes in each sampling technique was: Greenburg-Smith Impinger - 28, Midget Impinger - 22, ESP - lit. When the asbestos fibers were totaled, the curved line, which appears to be characteristic of fibers, was plotted on log-probability paper. The curve may be best described by defining a Standard Deviation for both the top and bottom halves of the curve. G.S. Impinger Midget Impinger ESP mg 2.22 y. 2.78 u U.17 p. ^upner 2.76 3.06 2.75 Qlowur 1.71 1.76 i DOCUMENT WAS NOT A RECORD OF INDUSTRIES, INC. DID NOT V OM FILES.AND CANNOT BE mi. PPG INDUSTRIES, IMf. . 2.18 'bB 00 20940 l 3423 Chief, Engineering Section -- 8/21/63 It is interesting to note that 19$ of the ESP sample had a fiber length greater than 10 p while only 8.5/S of the G.S. Impinger sample was greater than 10 p. The corresponding Midget Impinger figure was 13$. Conclusions that can be drawn from these experiments are difficult to concretely formulate. However, it appears that the Greenburg-Smith Impinger does tend to break-up the asbestos fibers upon impingement and give a smaller geometric mean than the ESP which is a relatively gentle method of collection. Hence, when fibers are reduced in size by impingement a spurious dus.t concentration may be obtained. A new means of collecting asbestos fiber was developed at the California Bureau of Occupational Health. Two types of filter papers, a green Gelman Filter and a black Millipore Filter, were U3ed. Illumination was achieved with a Zeiss Epi-Illunination Condenser which delivered incident light to the stage. Dark field Epi-Hlumination gave a sharper image on the colored filters than Light Field Epi-Hlunination. Fibers of asbestos are well defined against the opaque background of tile filter, A UOX objective lens with a numerical aperture of 0.61 and a 1QX eyepiece lens were used in the fiber identification. Filter papers with 0.8 p pore size were used for the collection of the dU3t. This gives rise to the question of how much of the dust collects be low the surface of the filter and is not seen by the observer. This is presently under investigation. Roger C. Grimm SJU Sanitary Engineer Engineering Section Research and Technical Services Branch / THIS DOCUMENT WAS NOT A REC0SD OF PPG INDUSTRIES, INC. DID C0r CO;'.'-; 'OM IT'S FILES AND CANNOT BE Ao ; BY PPG INDUSTRIES, INC. 1 BB 0020941 | 3433