Document v6L6bp7Ebqbo63vVZM7gOrqkw

Ref: Copy: Dl/JKH DTH/KOP/RAJ J PK/.fK/NR/31l/RS/Llb . RAJ: GA' To: Hr. J. D. Pennington, J. I. Roberta Ltd., 4 Horwioh. Physics Rsf: Work by: fi:- 1932/5 R. Clayton . I. Harness Written by: Approved by: S. Ho^xais. Date: 2nd November, 1965 SUBJECT Evaluation of Airborne Dust Levels during the spraying of "Limpet" Asbestos-Cement at Beljhlll Swimming Baths (2i.e.65) OBJECT To assess the efficiency of pre-daoping techniques at an actual spraying site. INTRODUCTION Earlier tests (Ref.l) carried out in 196L in the experimental tunnel at J. 1. Roborts Ltd., Horwich havo indicated that a reduction in airborne dust oocurs when "Limpet" .spray .fibro is pro--damped with a Calgon solution.'-^ It was recommended however, that these findings should be confirmed by4 tests carried out .on an actual spraying site and therefore, in'due course, a aeries of tests at Belshiil swimming baths was arranged.'''This report .details the work carried out at this location, pre--damping with.water'only, in addition to Calgon. ' ' ' L( Of ^Qun C0?R:LU 1 311,I1)"H31 44 . -. /;* }f'/>,C/ 'is - '*?//// 1. Pre-damping L'iT.25/l6 spray-fibre with either . Calgon or water reduces the resultant airborne dust levels in the vicinity of the sprayer. The results obtained actually favour the "-.vater pre-damped" material. This is contrary to expectation. 2. Dust levels remained relatively high for at least ten minutea after epraying had ceased.' ;44.V> | ' -r 3. A considerable health haiard4'ls indicated when the "Limpet" is stripped in the dry state. RBC OMtlEHDATIQNS 1. That wherever possible "Limpet" spray, fibre should be pre-danped prior to application. 2. That further work be carried out at an experimental site at Horwich to establish the differences due to pre-damping with water and pre-damping with Calgon. 3. That respirators be continued to be worn after spraying has ceased by personnel frequenting the spray area. L. That, prior to the commencement of stripping operations, tho applied spray medium be thoroughly soaked with water. suiivjvnr ,,. J Airborne dust tests have been carried out during the application of "Limpet" asbestos-cement spray on site at a swimming baths under construction at Belshiil (Hr. Glasgow). Membrane Piltor samples have been taken in order to assess the effloienoy of pre-damping techniques. The results show that both water and a Ifl Calgon solution are effec tive in reduoing the airborno dust level.' Continued: MO 038 3 EO'irPVSilT AilD KATZRLU. USED Standard Straight Cun (2* diameter) Hi Spray machine LW.25/16 Spra7 mixture with TS/2 bohding emulsion Pre-uanping - 250 ocs of damping medium per 10 lbs of spray-fibre DETAILED REPORT (a) Spray Application The LT.25/l6 mixture was sprayed onto an area approximately _ 10 feet b7 to feet in tho centre of the concrete celling. Tho " same 100 sq ft section was irlppcd and dousod with water before and after each of the trial periods. A reasonable"settling" period being allowed between tho various treatments. The spray-gun oporatpr stood on planks suspended approximately ' 7 feet , from thu celling. There was no measurable air moToment in the sampling area. (b) Sampling and Counting Techniques ,J Membrane filters ero used for collecting tho airborne duat, the sampling heads being positioned^ at head height at two dia gonally opposite corners of tho spray area. Four 5 mlnutos samples (flow rate'= 200 ccs/min),were'taken with each of tho 2 heads for each of^he, J spraying conditions. The counting technique'used was that ,,stipulated by the A.R.C. (Ref.2), only 5p to 100fibres*.being considered fsr the calculation of the dust concentrations. However, in order to produoe complete fibre size distributions it was also neoessary to oount fibres shorter than 5>* and'.longer than 100^. ' 1 '* * '** . . * / (0) Results /\ ` '' ' The dust concentrations and fibre size dictrisutions are tabulated in Appendix I and II respectively. Log-probability plots of the size distributions arc shown in Appendix III. *. .1.. : : . * (d) Discussion of Results Run 1. Stripping Spray fibre had already been applied to the test area tho previous week. Dust samples taken whilst this area was stripped "dry* yielded results of Cl .J* and 106.7 fibres per cc, indicating that an excessive health hazard exists when tho fibre is not damped before stripping. . Runs 2-5. L.7.25/lS Pre-damocd with 1* Caleon Solution Unfortunately an Insufficient settling period was allowed before the first trial commenced and Run 2 produced relatively high dust concentrations (2L..8 ana 33.0 f/eo). The remaining tests gave results varying from 6.6 to IL.i. fibres per 00. Runs 6-b, L17. 25/l6 . Pre--lamscd with Plater Thore ore two anomalous counts in this set of results, tho last run (9) producing -lust concentrations of 36.0 and 7U.6 f/cc. Figures ranging from 2.2 to 8.9 f/cc were obtained for the remaining samples and if loun 9 is omitted, it appears that pre damping with water is as effective as pre-damping with a Calgon solution. Thia is contrary to expectation. Continued: M00384 Puns iC-n. 1.ff.25/l!> - Wo Prs-.laaoing ' Those spraying conditions produced greatly increased dust luvels, results ranging'from 54..9 to 260.0 f/cc being obtained. They are approximately 10 times higher tluin the figures associated with the pro-damped trials and apparently confirm, that pre-damplru is advantageous in reducing the airborne dust in the vicinity of the sprayer. . Huns 14 and 15. Dust Hazard after Spraying These samples were taken in order to measure the amount of dust remaining airborne al'ter spraying had ceased. The membrane ' filter sample taken for the 5 minute period immediately after spraying gave a mean dust level of 21.4 f/co, a mean of 10.5 f/co being obtained for the following 5 minutes. These counts indicate that It is unwise for a spray-gun operator or cersonnel I frequenting the sorev area to.remove their respirators soon after spraying, a "safe time" will be determined by the rate of deoay of the dust level which in turn will depend upon the environment and the movement of air in the spraying zone. Sits Distributions 1 ,0 _ / 7. ^' . The log probability plots (see Appendix III) of the percentage frequencies tabulated in'Appendix .II are linear, only points for fibros less'thany5>fdiverging from'the straight lines. Although the curves, for Jthe three ^spraying-'conditions sro quite ' separate the difference.in?size distributions is only marginal. The slopes for the pro-danpod,/runs `and tvence tho shape of their distributions are similarJi^The''lo-dumped counts however result in a different slope, the proportion-of longer fibres being greater. No doubt the settling velooity'of these larger fibres is greatly increased when "wettei" by the. damping media and would therefore not-be-collected by the membrane filters (which were in a plane vertical 'to the floor). . ' ' RETIRifIC'iS "An assessment of the concentration of airborne dust produoed by the ."iimpot" Asbestos-Cement Spray Process" by I. Harness. ' (14.7.64) ' "Developments in Dust Sampling and Counting techniques in the Asbestos Industry" by Dr. S. Holmes. (Oct. 196i) MO 03 8 fj AJ'Prrarti Results of Airborne Dust Samples Tajcon During the Application of "Linpot* Spray Fibre on Site at Belshill (llr. Glasgow) Run 1 Conditions Under Test Spray fibre stripped from roof dry Dust Concentration* (F/co) 81.4 106.7 Approximately 10 Minutes Settling Period 2 M. 25/16 pro-damped with 1J{ Calgon solution 3 4, - err. // f> 5' Of - i.i ' 24.8 33.0 8.6 14.4 12.2 12.2 8.3 6.6 Approximately 30 Minutes Settling Period ` nr .' - *''/?_ ' 6 Bl.25/16" pro-dapod with water ' 6.8 7 r* " c*-*.v . .. . . ' 4.5 t , 8.9 4.3 8 #.**/ . 2.4 2.2 9 36.0 i -A'- 74.6 "`V Approximately 60 Minutes Settling Period (Lunch) 10 11 12 "* 13 UT.25/16 with no pro-damping ' m 14 0-5 minutes after spraying had ceasod' 15 5r10 76.2 54.9 151.4 81.7 66.3 118.8 69.4 2S0.0 21.4 10.5 : Calculated for fibres 5p - 100m AA00386 APPENDIX n Uaan Percentage SI:a Distributions of Dust Samples collootad during tha sprtyrins of 'Limpet* LT 25/l6 Asbestos Cement (Bolshill, 24.8.65.) s_ ''Vfo:, . > VvVl7ibre Length'* <5 5-10 (a) Predumped, with IjS Calgon 44. 3 31.5 (b) Pradomped with water . 3^-9 31.9 (o) Unpredoflipfld 26.1 35.1* O io-so 20-50 50-100 >100 ?*-P ^ 12.2 > 'v; 15.4 io.a 2.1 4.9 1.3 2.1 lQ.9. 15.1 3.7 0.8 ' MO 0387 h g?, Si? M up *r ^ g.^ N.X.A C.Co.Ltd. Aabostoa and Healtn Statement by Dr. J. T. Knox, Medical Conaultant to Turner <4 Newell Ltd. Turner & Newall Ltd. has been aware of the hazards associated with asbestos manufacture since the early 30*a. Following the introduction of the Aebeetoa Regulation." in 1932 certain processea in the factories of Newalla Insulation & Chemical Co. Ltd. (then known as The Washington Chemical ? Cc. Ltd.} were designated as needing speci.-.l attention to dust control and ventilation. The arrangements made for these processes completely satisfy the Government factory inspector. Men and women vorxing on these processes have to be given regular statutory medical inspections. The kind of tumour referred to in recent press articles (mesothelioma) is extremely rare and is not thought to be associated with the type of asbostos used in those insulation products made at Washington which Incorporate asbeitoa, X am not aware of any environmental hazard to people living or working near this Newalla plant. The asbestos industry as a whole, and Turner A Newall Ltd. in particular, has for many years given much thought, money and effort to the auppreoaion of asbestos dust and is Contd. PLAINTIFFS EXHIBIT TA/-7/f 2 continuously applying improved methods to this and. It has sponsored extensive medical iftves-t-igatTbh and programmes of scientific research at universities and elsewhere on the problems associated with asbestos and health. M.B. No asbestos is used in the manufacturing processes of the Paisley plant of Nevalls Insulation & Chemical Co. Ltd.