Document 3e4L3B1ZyqQzr2nOJXaa8raaD

BUSINESS CONFIDENTIAL ^CZ";~ > AUG 3 t i97g INFORMAL REPORT m. c. TH Report No.: Date: Work By: Written By: 2196-64 August 24, 1978 B. L. Ingalls & G. J. Spencer H. B. Rhodes THE OCCURRENCE OF ULTRA-FINE FIBERS IN "CALIDRIA" RG-244 ASBESTOS SUMMARY AND CONSULSIONS During the latter half of 1977 several very high fiber counts, i.e., 20-40 fibers/cc, occurred during customer use of RG-244. The counts were associated with large amounts of extremely fine diameter fibers in the air samples. It was not clear whether these fibers were due to a change in the product or had been present in the past and gone undetected. In order to answer this question sixty-five filters from 36 customer locations collected in the time period of 1973-1977 were recounted. Extreme care and attention was devoted to the detection of ultra-fine fibers. The results obtained support the following: 1. Prior to 1975 ultra-fine fibers were probably not present in measurable amounts. y 2. After the expanded plant went on-stream in 1975 until mid-TSi^ such fibers were present at 30-45% of locations tested in sufficient quantitites to yield maximum ceiling airborne concentrations that were generally in the 1-3 fiber/cc range. 3. During the spring of 1977 occasional batches of product were made that contained a sharply increased amount of fines. This was possibly due to increased throughput through the dryer. These products resulted in several 20-40 fibers/cc counts. 4. The sudden appearance of high counts was real and not a result of prior counting omissions. 5. Only one customer test has been run in 1978. The fines are therefore being checked with regular bagger samples obtained at the plant. This work will be reported elsewhere. BACKGROUND Union Carbide has provided an asbestos fiber counting service to customers since 1973. In the time period 1973-1977 about 45 counts were made during the commercial handling of RG-244 asbestos. The highest results obtained until about the middle of 1977 were less than 3 fibers/cc with values under 1 fiber/cc most typical. A summary of these counts, taken from the October 1, 1977 update of the "Calidria Asbestos RG-244 Health and 0SHA Information" brochure ts shown in Tables I, II and II. These tables include all of the available RG-244 results available through August 1977 except for a couple of filters that were known to be heavily contaminated with Nytal tremolitic talc. UCC 010664 2- - BACKGROUND (Cont'd.) In the later part of 1977 counts in the 20-40 fiber/cc range occurred at three customer locations, one of which was in confirmation of a very high count found by an OSHA inspector. These high counts were largely due to the presence of a great multiplicity of extremely fine diameter fibers at the limit of detection of the counting method used. A long-time customer, Chrysler, who used excellent dust control equipment, also mentioned informally at that time that their counts which in the past had been in the low tenths of a fiber/cc now showed an occasional result in the 1-2 fiber/cc range. OBJECTIVE OF THE PRESENT STUDY The recent detection of large quantities of fine fiber in several RG-244 customer tests can be accounted for in two ways: 1. Ultra-fine material has always been present, at least sporadically, and has largely escaped detection in the past. 2. The occurrence in sufficient quantities to cause the high dust counts is the result of a recent change in the product, i.e., since about mid-1977. The objective of this study was to distinguish, to the extent practicable, between these two alternatives. THE ANALYTICAL PROBLEM Asbestos fibers are counted with an optical microscope at 400-450X using phase contrast illumination. Only fibers longer than 5y with L/D ratios greater than 3 are counted. The 5y length does not present any particular difficulty but as the diameters become smaller, the limit of resolution of the microscope is reached and the fibers, although longer than 5y, can no longer be seen. This occurs in the diameter range of 0.25-0.5y. The limit is not a sharp line but a "grey" area which varies with such things as the microscope optics, the skill of the operator, the care which the operator takes in setting up and adjusting the equipment, the visual acuity of the operator, the physical condition of the operator, the quality of the filter paper and the condition of the clearing solution used to prepare the slide. The limit can differ from day to day with the same operator using the same equipment. It has also been our experience in working with ultra-fine fibers that they are very easy to miss completely unless the operator specifically looks for such material. PROCEDURE It is the practice at the Niagara Falls laboratory to retain the unused portion of all filters collected. Filters were found to be still available for 36 locations where RG-244 counts had been made in the 1973-1977 time period. UCC 010665 -3- PROCEDURE (Cont'd.) ' In order to keep the counting load at a reasonable level only part of the available filters were recounted. Accordi ngly, several filters which were expected to represent the highest levels were selected to represent each location. These were mounted and recounted by our most active operator with great care and with careful searching for ultra-fine particles. A total of 65 filters were counted. . PRESENTATION AND DISCUSSION OF RESULTS The results are summarized in Table IV. The data are listed chronologically by year with each location assigned a number to facilitate identification. The original count (Column y), the new count (Column x), and the difference, x-y, are shown for each filter. The Occurrence of Fine Fibers The recent recounts where ultra-fine fibers were the object of specific attention are obviously the best data to examine for the historical occurrence of such fibers. These counts,.in fiber/cc, are shown graphically in chronological order in Figure 1. Where ultra-fine fibers were seen, the bars are dark. Where none were found, the bars are light. Note also in the figure that a split vertical scale has been used wherein the units for counts greater than 5 fibers/cc have been reduced by a factor of 10. The occurrence of fine fibers is summarized in the table below: Year No. of Locations Recounted Occurrence of Fine Fibers No. of Locations % of Locations 1973 1974 1975 1976 1977 2 2 11 10 11 00 00 5 45 3 30 5 45 During the two-and-a-half year period of 1973, 1974 and through March of 1975 only one flocculated bunch of fines was found on one filter. For the remainder of 1975, 1976, and 1977 fines occurred sporadically at 30-45% of the locations tested. If the fines had been present prior to March 1975 at the same frequency observed later, two or three occurrences would have been expected at these eight locations. This suggests that measurable quantities of very fine fibers occurred rarely, if at all, before 1975. They have clearly been present with considerable frequency since that time. The quantity of fines present, particularly with regard to the potential to give occupational exposures above the present OSHA ceiling limit of 10 fibers/cc also shows a distinct pattern. In the two-and-a-half year period from 1975 to mid-1977 there was only one count above 10 fibers/cc, i.e., 1975 - No. 5 which was just above at 11.3 fibers/cc. The highest counts in this time span were generally in the range of 2-3 fibers/cc. In the second half of 1977, however, three counts ranging from 18 to 40 fibers/cc were obtained. (Note scale change in the UCC 010666 -4- figure.) One of these (1977 - No. 11) verified an OSHA inspection count of around 25 fibers/cc obtained at the same location a month earlier. Examination of these three very high results in detail shows that in one case (1977 - No. 6) substantial quantities of Nytal talc were used at the same time as the RG-244. This talc generates extremely fine fibers which cannot be distinguished optically from chrysotile asbestos. It is thus not possible to determine the relative contributions of each to the total count so this result cannot be given much weight in the present assessment. In the second location (1977 - No. 8) a "homemade" dust control setup was in use. Air from over the mix tank was sucked through a flexible duct by an exhaust fan, passed through a filter, and discharged into a second room. The result shows the presence of substantial quantities of fines in the asbestos being dumped but is not directly correctable with worker exposure in the breathing zone. The third high count occurred in two samples from 1977, Location No. 11. Both of these took place while an operator was dumping bags, folding them, and inserting them into a metal drum. When the bag entered the drum, a blowback of air resulted. A repeated test several hours later which differed in that the operator tossed the empty bags on a pallet which was subsequently removed by a forklift, gave much lower counts in the 1-2 fiber/cc range. As noted previously, however, OSHA had reported a high count at this location earlier. In summary, there have been two confirmed occurrences of high exposure, ^20-30 fibers/cc, one of potential high exposure, and one of possible but not definite high exposure due to ultra-fine fibers in RG-244 in a six-month period in the second half of 1977. Although these high levels clearly relate to the way the asbestos was handled, it is equally important to note that over the four-and-a-half years prior to that, only one case barely above 10 fibers/cc had been identified. Some of these 30 earlier locations tested should have shown very high counts if the potential for such levels was present in the material being handled. The product being used by customers in the latter half of 1977 was occasionally different from that produced in the past. The pattern just described appears to correlate with certain plant operations. In the spring of 1975 the expanded circuit was started up. Increased throughput in the dryer would give higher percentages of fine fibers in the product and correspondly such fibers would be found in airborne dust samples. In the spring of 1977 the production rate of RG-244 was again increased substantially and campaigning through the dryer was practiced frequently. It seems likely that there were intervals where a number of bags of product contained a sharply increased amount of fines. This would result in a high potential for airborne dust generation, particularly if the bag was handled carelessly in any way. UCC 010667 -5- Considering the experimental results together with the knowledge of the RG-244 circuit operations, the following picture of the historical occurrence of fine fibers in the product can be drawn: 1. Until the spring of 1975 fine fibers were present at extremely rare intervals, if at all. 2. Following the plant expansion completed in the spring of 1975, measurable amounts of fines were present in the airborne dust at 30-50% of the users' locations. 3. Until mid-1975 the amount of fines present was small enough so that ceiling exposures were generally still in the 1-3 fiber/cc range. 4. During 1977, probably in the second and/or third quarters, RG-244 was produced occasional 1,y that contained much higher levels of fines than in previous years. Fiber counts of 20-40 fibers/cc could be produced under conditions encountered commercially with these materials. The extent of the fines problem in 1978 operations remains an open question. The plant continues to run at a high throughput. The only user test carried out was in February and the highest count obtained was an encouraging 0.1 fiber/cc. No laboratory test of relative dustiness is available. The possibility of developing such a test was considered and dropped when it became evident that it would be a major project to work out the test and obtain the correlation with actual field use conditions that would be necessary. A continuing monitoring of regular samples from the RG-244 bagger operation at the plant is in progress, however, and is being reported elsewhere. The Impact of Fine Fibers in Prior Dust Counts The emperical precision of the optical counting method used in this work is the subject of continuing debate. Differences of 50-100% between replicate counts on the same filter are quite common and larger variations can occur as the quantity of fiber on the filter becomes smaller. It is well beyond the scope of this study to analyze these results in a general way. Only the specific effects on the samples where fine fibers were found in the second count will be examined. Figure 2 is a repeat of Figure 1 with the original count results for the filters containing fine fibers indicated by the solid horizontal lines. Out of 19 filters containing fines there are only two where large changes occurred. These were 1975 - No. 5 from 1.3 to 11.2 fibers/cc and 1977 - No. 8 from 0.5 to 17.92 fibers/cc. There is no doubt that the fines were missed in the initial counts on these two filters. UCC 010668 6- - The Impact of Fine Fibers in Prior Dust Counts (Cont'd.) The other three high counts from 1977 show variations between replicates which are well within the recognized precision of the method. The next highest results ranged from 2-3 fibers/cc and occurred at four locations in 1975 and 1976, i.e., 1975 - Nos. 4 and 8 and 1976 - Nos. 3 and 6. These have a consistent bias of plus 2-3 fibers/cc. Since differences are all in the same direction, they are probably statis tically significant but are also of limited practical importance since the results are far below the allowable OSHA ceiling limit. Overall, then, only two out of the 65 filters counted showed important errors due to the failure to "see" the ultra-fine fibers. Considering the . extremely difficult nature of these samples, this is considered to be very good counter performance but continued special attention to RG-244 samples is needed and will be provided. The sudden appearance of occasional very high counts in 1977 was the result of a change in the product not a change in counting skills or equipment. HBR/rmm Attachments Harrison UCC 010669 AIRBORNE ASBESTOS FIBER COUNTS 0). "LARGE-SCALE" DUMPING OF RG-244 HOQ-450 lb./Batch) Plant A B C Data Reference -- 1929-46-2 1929-30-2 D 1929-56-1 E 1929-50-3 F 1929-26-3 G 1929-24-2 H 1929-16-1 I 2119-8-9 0 2119-6-23 K 2119-12-9 Description of Operation Dump Sample Bags Time Time Dumped (Min.) (Min.) 10 10 10 14 9 9 15 21 21 36 12 12 15 8 8 45 20 20 10 24 24 28 15 15 13 8 8 20 10 10 34 72 72 Special Ventilation'4' CEILING Concentrat Fiber Count (Fibers/cc. >5u) None None Hood over thin tank opening 0.7 1.2 0.7 None 2.4 None * 0.5 None 1.6 Hood over mixing area 0.8 None 2.8 None 0.4 None 0.4 None 0.9 ^All samples collected in the breathing zone of the operator dumping the RG-244. fv2'lSpecial ventilation refers to dust collection equipment at or near the dumping area that is specifically intended for dust control during the dumping operation. All plants had varying measures of overall building ventilation. Plant A B B J Data Reference -- 1929-40-3 1929-40-5 2119-6-23 TABLE II AIRBORNE ASBESTOS FIBER COUNTS ' EMPTY BAG REMOVAL Description of Operation Sample taken 3 feet above waste disposal drum for empty bags. (During dumping.) Directly over empty bag stacking area. Taken during dump. Empty bag storage area. Taken during dump as bags were put in. Sample Time (Min.) 10 23 24 24 Fiber Count (Fibers/cc. >5u) 0.4 0.6 0.4 0.1 TABLE III AIRBORNE ASBESTOS FIBER COUNTS^ "SMALL-SCALE " DUMPING OF RG-244 (1-25 lbs./Batch) End Use FurInI iture HoIIlding II II . II II GIeI l CoIaI t MIIfg. ArtIIificial BrIiIck MIIfg. Roof Coating Mfg. Cel Coat Polyester Epoxy 11 Gel Coat PIIutty Sealant CauIIlking CoImI pound Patching Compound Pounds Dumped 1 12 1 6 9 3 5 1.5 12 10.5 25 6.3 6.3 20* 20 20 15 6 6 3.3 Dump Time (Min.) 10 2.5 11 8 25 3 4 10 13 13 n 41 39 10 35 34 19 3 11 10 Sample Time (Min.) 10 2.5 n 8 25 3 4 10 13 13 11 41 39 10 35 34 19 3 11 10 Ventilation^ ' Hone None None Good Hood None None Good Hood None None Outdoors None None None Exhaust Fan Exhaust Fan None None None None Ceiling Concentration Fiber Count (Fibers/cc >5u) 1.5 1.1 2.0 0.9 0.7 1.2 0.9 0.4 1.1 0.3 0:1 i.o 2.0 0.6* . 2.1 0.2 0.2 0.5 0.2 0.7 0)All sar.ples collected in the breathing zone of the operator dumping the R6-244. (2) . .. . Special ventilation refers to dust collection equipment at or near the dumping area that is specifically intended for dust control during the dumping operation. All plants had varying measures of overall building ventilation. * Sample taken during dump and bag disposal. UCC 010671 Loc. Year No. Company 1973 1 Hughes Chemical 2 Kristal Kraft TAME IV SUMMARY RG-244 AIR6JKN~cTlBCR COUNTS Date Sample toe. Honitored No. Operation Description Original Count (y) Recount (x) Fibers Date Fibers yor cc Recounted per cc Conments MI 8-20-73 2-245 P - During use of RG-244. 1.0 4-10-78 0.2** Fine particulate. * FI 8-24-73 5 P - Dump 9 pounds. 0.7 5-3-78 0.6 No fine fibers. Difference Between Counts (x-y) -0.8 -0.1 1974 1 2 Tuff Kote Kinetics Inc. MI 4-30-74 C-S34 P - Dump 25 pounds. NM 8-13-74 1-13 P - Shaping pipe. 0.3 5-3-78 1.2 Fine particulate. poor background. 0.3 5-2-78 0.6 No fine fibers. +0.9 +0.3 1975 1 Bridgeport Chemical 2 Glassflake Corp. 3 (Cargill Corpany jCargill Corpany (Alpha Chemical 4 lAlpha Chemical FL 2-2-75 L-10 P - Handling asbestos. FL 2-18-75 N-19 P - Dump 7 pounds. CA 2-19-75 Q-39 P - Dump 15 bags. CA 2-19-75 Q-36 P - Empty bag removal. FL 5-7-75 A-21 P - Handling empty bags. FL 5-7-75 A-64 P - Dump 8 bags. 0.2 0 1.3 1.3 0.7 0.4 5 Steadfast Rubber HA 5-20-75 A-81 P - Weigh & dump 10 pounds. 1.3 6 Acme Fiberalass Co. CA 6-13-75 A-77 P - Grinding fiberglass tubes. 2.1 (International Paint Co. NJ 8-13-75 B-82 P - Dump 8 bags into Cowles . 1.24 7 ^International Paint Co. NJ 8-13-75 B-71 P - Dump RG-244, bag dis- 0.65 posal. (Interplastic Corp. 8 jlntorplastic Corp. MN 9-5-75 B-33 P - Dump 28 bags. MN 9-5-75 B-18 P - After dump. 1.0 0.2 9 Interplastic Corp. OH 9-18-75 B-49 P - After dump. 0.3 (Glove Coaters 10 ( jciove Coaters ( ( 11 General Tire ' 1976 1 2 Alpha Chemical (A-Z A.Z (Freeman Chemical 3 ^Freeman Chemical ( (Apperson 4 jApperson (Apperson 5 U.S. Plastic S Chemical Corp. 6 Solvean Laboratories HI 9-26-75 B-29 P - 90 pounds RG-244 to mixer. 5.3 HI 9-26-75 C-81 A - During and after RG-244 0.3 dump 15' from mixer, 5' above floor. OH 12-10-75 D-25 P - Dump 10 pounds. 0.3 CA 1-19-76 D-34 P - Dump 2-1/2 bags. FL 3-3-76 0-76 P - Dump 13 bags. FL 3-3-76 C-97 A - 13 bags dumped. 0.1 0.3 0.4 WI 3-25-76 0-98 P - Dump 20 pounds. WI 3-25-76 0-45 P - After dumo. 0.6 0.7 FL 3-29-76 0-75 A - Unloading pallets. FL 3-29-76 0-84 P - Forklift operator. FL 4-1-76 0-6 A - Unloading pallets. NY 7-29-76 F-36 A Weighing 3 pounds. 0.1 <0.1 1.0 0.8 CA 8-3-76 1 P Weigh t dump 340 lbs. 0.9 7 Tohoku Plastic Engineering Japan 9-8-76 1 P - Dump 1.5 kg RG-244. (Nytal 300 talc also dumped.) (Interplastic Corporation OK 10-12-76 F-43 A During dump. 8 |lnterp1astic Corporation OK 10-12-76 G-38 P Dump 30 pounds. 0.7 0.2 0.5 9 Red Devil Inc. (Metro Warehouse 10 {Metro Warehouse (Metro Warehouse OK 10-12-76 F-33 P - Weigh t dump 6 pounds. <0.1 MO 11-22-76 -76 P - Forklift HO 11-22-76 G-24 P - Forklift MO 11-22-76 F-69 P - Forklift 0.2 0.2 0.5 4-6-78 0.2 4-10-78 0.2 One very fine bundle. No fine fibers 4-6-78 4-6-78 0.4** No fine fibers. 0.4** No fine fibers. . 4-5-78 4-5-78 5-5-78 2.1* 0.4 11.2* Poor resolution, several planes. Fine fibers. Poor resolution, several planes. Some very fine fibers. 4-5-78 5.1 Poor resolution. 0 +0.2 -0.9 -0.9 +1.4 0 +9.9 +3 4-10-78 1.6 4-10-78 0.6 No fine fibers No fine fibers. +0.36 -0.05 5-1-78 2.3* Some very fine fibers. 5-1-78 0.1 No fine fibers. +1.3 -0.1 4-10-78 0.3 4-10-78 1.9 Poor resolution - several planes. Clear background. 0 -3.4 4-10-78 0.3 Fine particulate, some very fine fibers in areas not containing fine particulate. 0 4-10-78 0.3 No fine fibers. 0 4-5-78 0.2 One extremely fine bundle. +0.1 4-5-78 0.17 No fine fibers. 4-5-78 0.5 No fine fibers. +0.4 +0.1 5-1-78 2.8* Some very fine fibers. 5-1-78 0.5 Some fine fibers (not as many as D-98). +2.2 -0.2 4-5-78 5-1-78 4-6-78 5-5-78 0.1 No fine fibers. <0.1 No fine fibers. 0.04** No fine fibers. 0.3 No fine fibers. 0 0 -1.0 -0.5 5-5-78 5-3-78 2.04* 1.3 Some very fine fibers difficult to count. No fine fibers. 1.14 +0.6 5-3-78 5-3-78 0.3 1.3 No fine fibers. Poor background - granular looking. 0.1 0.8 5-5-78 0.9* No fine fibers. 0.8 5-2-78 5-2-78 5-2-78 0.6 0.1 0.7 No fine fibers. No fine fibers. No fine fibers. 0.4 -0.1 0.2 A Area P * Personal * Higher than original UCC 010672lo"er th4B orl9,Ml- Loc. Nn. Cowanv Date Sample toe. Monitored No. 2 Operation Description Original Count (y) Recount ( x) Fibers Fibers per cc Recounted per cc Conments Difference Between Counts (x-y) i Norton Corpany 2 Coatings 4 Plastic (Adcoat Inc. 3 jAdcoat Inc. NJ 2-16-77 R-38 P - Dump 15 pounds. 0.2 5-2-78 0.4 No fine fibers. AR 3-2-77 A-20 P - Weighing 1.6 pounds and dump. 0.2 4-6-78 0.9 Some fine fibers. * CA 3-30-77 8-39 P Dump 48 lbs.-outdoors. 0.1 4-5-78 0.4 No fine fibers. ca 3-30-77 B-38 A - After use of RG-244. 0.1 4-5-78 0.1 No fine fibers. +0.2 +0.7 0.3 0 (Carbollne Company Jcarboline Company (Carbollne Company 4 ^Carboline Company jcarboline Company (Carboline Corpany jcarboline Company 5 Chemex 6 Tnemec Inc. OH OH OH OH OH OH OH FL HO 7 Products Research and Chemical Corporation CA OH 8( i (Dayton Chem 6 Coat. OH 9 International Paint CA 10 Southern Imperial Coatings LA (Carbollne Company {Carboline Company (Carboline Company (Carboline Company 11 (Carboline Company Jcarboline Corpany (Carboline Company JCarboline Company CA CA CA CA CA CA CA CA (Carboline Company Jcarboline Company CA CA 4-S&6-77 K-4 P - Dump 50 pounds. 4-566-77 H-5 P - After 50 pound dump. 4-566-77 K- 36 P - Dump 179 pounds. 4-566-77 A-88 P - Normal duties. 4-566-77 R- 31 P - After 179 pound dump. 4-566-77 K-46 P - Weighing 179 pounds. 4-566-77 K-33 P - Weighing 50 pounds RG-244. 5-10-77 A-50 P - Dump 2 bags and bag disposal. 5-16-77 6 6-22-77 N-35 P - Dump 60 pounds. 0.8 0.16 0.2 0.01 0.4 0.13 0.18 0.28 28.5 5-1-78 5-1-78 5-1-78 5-1-78 5-1-78 5-2-78 5-1-78 1.03 0.1 0.3 0.1 0.8 0.3 0.7 '4-6-78 1.5* 5-5-78 39.8 6-30-77 B-35 P - Dump 70 pounds. 0.1 5-2-78 0.2 7-14-77 N-99 A - In outlet of exhaust through which filtered air was recirculated. (Re-checks by 8. L. Ingalls on 4-28-78) 7-14-77 N-98 P - Dump 20 pounds. 0.5 4-6-78 (9 400X) (9 1000X) 0.3 4-6-78 17.92 8.8 20.9 0.7 8-3-77 B-43 P - Dump 40 pounds. 0 4-10-78 0.54* 9-12-77 D-78 P - Dump 52 pounds. 8.6 6-5-78 12.7* 12-13-77 12-13-77 12-13-77 12-13-77 12-13-77 12-13-77 12-13-77 12-13-77 12-13-77 12-13-77 C-43 C-40 C-36 C-31 C-37 H-45 A-41 A-42 P - 220 pound dun?. P - 220 pound dump. P - Bag disposal. P - After dump. P - Dump 220 pounds. P - Dump 220 pounds. P - Bag disposal. P - Bag disposal. C-39 P - Bag disposal H-59 P - Bag disposal 44.5 5-2-78 27.8** 31.5 5-2-78 22.4** 0.5 5-2-78 0.8 0.4 5-2-78 0.4 1.4 5-2-78 0.94 0.4 5-2-78 0.4 0.3 5-2-78 0.7 5.8 5-2-78 1.4** 1.7 5-1-78 0.9** 0.4 5-2-78 0.4 Fine fibers Fine particulate Fine fibers, several planes. Chunky 6 fine particulate. No fine fibers. Chunky 6 fine particulate. Chunky particulate. +0.23 -0.06 +0.1 +0.09 +0.4 +0.17 0.52 Poor resolution, several planes. +1.22 Some extremely fine fibers, + 11.3 poor background due to particulate, several plar.es. Nytal 300 talc used during monitoring. No fine fibers +0.1 Extremely fine fibers - very +17.42 difficult to count - took 50 minutes to count only 50 fields. No fine fibers. +0.4 No fine fibers. +0.54 Heavily loaded with small and chunky particulate. +4.1 Fine fibers. Fine fibers. No fine fibers. No fine fibers. No fine fibers. No fine fibers. No fine fibers. Poor distribution observed on first count. Poor distribution No fine fibers. -16.7 -9.1 +0.3 0 -0.46 0 +0.4 -4.4 -0.8 0 A - Area P - Personal `Higher than original, "Lower than original. 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