Document 7OvdD77LVyDjZjZaxvK2M1dy6

ir*iii; P. T.lwrjhtw, W. 0. V.'. CUfk Cooper. M. 0. 1 - v- |X. a ' v. .V. i ) v.*>. V. |.( U-(.U) V.*' *7cicri+xla4'ji- (^aofis/i /vte&ctat&i 2100 MIL VIA STREET, BERKELEY. CAtlfORNIA 9*701 MAILING ADDRESS: P.0. BOX 772 h EXHIBIT Py-43*.rJ -!%-%% JL__ 1 July 13, 1970 ^1055^ Ttt0*-on (41$) HMiM A6BEST0S FIBER CONCENTRATIONS IN AIR FROM SPRAY FIREPROOFING OPERATIONS USING ZONOLITE PRODUCTS In order to determine concentrations of airborne asbestos during and after the application of vermicullte-asbestos cement r ,, materials In the fireproofing of structural steelf^oSseryations vere made at three construction sites In San Francisco on May 26, May 26 and June U, 1970. Consideration vas glren to the actual and potential exposures of (a) vorkmen carrying out the spray operation, (b) workers in allied trades nearby, and (c) the general public. Sites studied. Three spray operations vere surveyed: (l) the Embarcadero Center, vhere Mr. G. Connell vas spray contractor; (2} the P.G.and E. Headquarters Building, vhere the spray con tractor vas C & R Plastering, Inc. (Mr. Rasmussen); and (3) the Hilton Tovers, vhere Mr. G. Connell vas also the contractor. Methods . Airborne fiber concentrations veredetermined by drawing air through Milllpore type AA filters, vlth 0.6/Mrmean pore size. Samples vere taken in the breathing sones (BZ) of men working vlth the material and at various(locatlono surrounding the i operations. Air flovs ranged from 0.11 cubic feet per minute (cfm) 05200:: io S- ' | 4055^ in breathing zones to 1.6 cfm In areas more distant. Portions of the filters vere mounted on slides, and the fibers In 100 micro-, eoplc fields counted, using phase contrast microscopy at a magni fication of l*30x. The numbers of asbestos fibers seen vere converted to concentrations, expressed In fibers per milliliter of air, by taking Into account the area counted, the flov rate, and the sampling "time. Results. .. I , Embarcadero Center - Hay 26. 1970. r Spraying vas being con-' ducted on the blst floor of the b3-atory building. The three men< at vork at this site vere all plasterers; there vere no hodcarrlers. . The plasterers moved their ovn stages but did not clean the area as they vorked. The floor of the vork site vas covered to an es timated depth of tvo Inches vlth rebound and oversprayed fireproofing materials. The gun from vhlch the material vas being applied vas being operated at a relatively high air flov rate, resulting in con siderable rebound. 6amples vere taken (A) of the air in the breathing zones (BZ) of the gun operator and the man moving the stage from vhlch the operator vas vorklng; (B} of the air in the area surrounding the spray operation; (C) of the air moving through the l3rd floor (2 floors above the spray operation); (D) of the air in the breathing zone of the investigator as he moved around the spray operation (equivalent to the exposure vhlch might be experienced by a con- structlon vorker in the area); (E) of the air in the breathing * zone of the mixer operator vorklng on the ground floor. ^52Q0Z^V^ EMBARCADERO CENTER AIR SAMPLES 40559 Sample Humber -Area Asbestos fibers total f/ml f/ml ()5 um)* *5* (A) 51 (A) 1*9 (A) 147 (A) . ./ v 22U9 (B) >... 4 :: : 2250 (C) 56 (D) 1*8 (E) Spray operator's BZ M It It 7.96 2.63 " " " (Held near back of head to protect face of filter) 3.56 Stage mover's BZ 1.86 Area near spray (1-50 feet dis tant, some direct spray on filter)0.030 Background area, l*3rd floor (air flov past spray-encrusted drapes) Investigator's BZ 0.79. Mixing Operator's BZ 0.775 o CM O oa 6.5^ 2.18 3.16 1.55 0.028 0.016 0.60 0.710 "Present tentative occupational threshold limit value of 5 f/al is based on fibers greater than 5 micrometers in length. r. 1. (_ PC&E Building - May*28. 1970. A crev of 6, vith tvo guns operating simultaneously, vas at vork on the 21st floor. The first impression on arriving at the vork site vas of clcanlineoo and order. The hod-carriers, vhen not moving the stages,vere scraping the floor near each stage, and moving the accumulated rebound and overspray fireproofing material to a large central pile for removal. There vas a business-like atmosphere, and the crev appeared to be efficient. It vas noted that moving of the stages St as accomplished, for the most part, vlthout request fromtthe gun operator, but on the initiative of the hod-carriers. The spray used here appeared* to be drier than at the previous site, and vas being applied at a lover velocity and flov rate. The finished sprayed surface appeared to be somevhat rougher, but the build-up from leaving the gun in one -3- * 40560 ' place too long was less, leading to a more comfortable working pace for the operator and less direct rebound on hit face and person. Samplea were taken: (A) In the breathing tone of the gun operator; (B) in the breathing tone of the inveatlgator (equivalent to the breathing tone exposure of the hod-carrlera; (C) upwind and down wind (approximately) of the etagea, In the general area of the stages; (D) In the breathing zones of the mixer operators; () in the general area of the mixing operations; (T) one floor below the spray operations; and (0) in the general area of spray operations.  Sample Number 53 (A) 1 (A) 55 (B) . . . 2 (c) >* \% .r 3 (c) 6o (D) 52 (D) 59 (E) 61 (E) 2ll7 (F) k (c) 5 (0) 22>9 (0) i* 05200^'irt * 5"* 40561 _ . PG4E AIR SAMPLES Area Asbestos Fibers 1 Total f/ml f/nl"(>5 us) 6pray operator's BZ 1 II l 3.32 3.15 2.91 2.61* r* BZ of Investigator, close to spray stage, walking with hod-carrier 0.16 0.11* Area, 1*0 feet upvlnd of single stage Tair flow variable) 0.13 0.11 Area, 1*0 feet dovnvlnd of stage (air flow variable) 0.2$ 0.23 CM "" ' 0 Mixing operator's BZ (wind avay f roa) o.$o Mixing operator's BZ (wind*toward) 1.1*2 l'. 25 Mixing area (between two mixing operators) .... _ .. 1.09. ____ _ 0.. 9.8 ___ Mixing area (between two nixing operators) ` Background, 1 floor below spray operations, most air flow not through the building .to filter, but variable. 1.31* O.OH* 1.1b 0.011 Area, between two stages (current to pump cut off at variable times, total flow through filter uncertain) 0.038 0.036 Area, 30 feet from stages (2) 0.071 0.061 Area, 35 feet from stage, (air flow in area uncertain and variable) 0.36 0.3U "Present occupational threshold limit value of 5 f/nl Is based on fibers greater than 5 micrometers in length. -5- #J7 r-'i >i* : .1 ' <*>: ,'.V*t**K<? ^" #! 052002'?'? >5*40562 Hilton Towers - June ^ , 1970. 6pray operations were underway on the 21st floor of thla building. There vaa a steady westerly vind through the building. A second gun crev vaa spraying stairways on the 30th and 31et floors. The Job site vaa clean and orderly In appearance (considering the nature of the operation) ( and the hodcarrier vaa cleaning the floor as the stage vas moved. The air flov rate and rate of application vaa somewhat higher than on the PGfcE Job* but not as high as on the first Job. The mixing area vas in the basement of the building, but there vas a good flov of air through the mixing area, secondary to the high vind speeds aloft. Air samples vers taken in (A) the spray operator's byeathlng tone, (B) the hodcarrier's breathing tone, (C) upvind and dovnvind of the area of the epray stage, (D) on the up-vind side of the building on the 35th* floor (the uppermost level at vhich continuous flooring had been Installed), (E) dovnvind of the 17th floor, (F) in the mixing opera tor's breathing tone, and (G) in the area of the mixing operation. Sample Number 62 (A) .64 (B) 226U (C) 2262(C) 73 (D) 2259 (E) 57 (F) 69 (F) 63 (0) HILTON TOWERS AIR SAMPLES Area Asbestos total f/ml f/ml*(>5 Spray operator's BZ 2.18 Hod Carrier's BZ 0.1*9 Upvind of stage 0.0007 Dovnvind of stage o.oifcT Upvind of 35th floor - Background (Prob. non-lso-kinetic flov at none . filter face; validity as a seen final measure of fiber background level?) 2.20 0.33 0.0007 0.0137 none seen Dovnvind of 17th floor (four floors belov spray operators) Mixing operator's BZ Mixing operator's BZ Mixing Area 0.0017 1.61 0.55 0.1*3 0.0017 1 .>*5 0.50 0.38 -6 i T a*'\i K-,v. - >? V ' * ! ;< \ (k .OOZto'f 40S63 Ambient Air Sampling. Air samples vere taken In upwind and downwind street areas around the Hilton Towers on June 23. 1970. Pu&ps drawing air through Milllpore filters at flow rates from 0.057 to 0.11 cubic feet per ninute were ueed. A total of 8 samples vere taken; 4 upwind and 4 downwind. 2 upwind and.2 downvind samples vere taken In the morning and afternoon. The aamplee in the upwind area (vest of the hotel) vere of two kinds: stationary samples (in parking lot of the 500 block of Leavenworth Street), and "movlngM samples (in the general area bounded by Turk. Jones. Post, and Hyde streets). The moving samples vere taken by an investigator wearing a filter holder. The downwind eamples vere taken in the same way. Stationary samples vere taken at two locations: the morning sample from an open window (2nd floor level) at 150 Pove'll Street and the ' afternoon sample on the roof of a parking lot office one block vest of the Hilton. (The moving samples vere taken' in the area bounded by Market. Grant. Geary and Mason streets.) Morning Stationary Moving Afternoon Stationary Moving Air Sampling Results (flbers/ml) Upwind Sensitivity Downwind Sensitivity 0.024 0.014 0.077 0.009 0.005 0.005 0.009 0.005 . 0.016 0.042 0.015 0.005 0.016 0.009 0.005 0.005 tt 7 i I ' ( ~00;mc''54O564 D1acuoslon. The occupational exposures to spray operators vere not above the currently recommended threshold Unit values Tor asbestos exposures, vhich have recently been recommended for reduction to 5 fl/ml (fibers over 5 micrometers in length) based on a time-weighted average oyer an 6 hour work day, 5 days a week. Only one sample higher than this level was found. The vide varia bility is normal for this type of operation. Heverthelesa, there is little margin of safety and the potential risk from asbestos Inhalation is such that ve would recommend that exposures be reduced even further. Concentrations dropped off rapidly in the adjacent areas and may reach levels of the ambient air. Background or ambient air concentrations ranged from less than 1 fiber per liter of air (upwind high in Hilton Towers) to 77 fibers per liter at ground level upwind at Hilton Towers. The variability reflected the variety of wind conditions during the study, multiple' construction projects in the- downtown area, as veil as Inherent sampling variations. There is no way to estimate the contribution of the fireproofing spray Jobs being studied to the overall back ground fiber level in Sen Francisco. In other studies, in East Bay, ve have found the average asbestos fiber concentrations to ~ .c/z. s be approximately JL_f/Ht*T but sometimes going as high as 12 f/liter. In brief, fiber concentrations in spray areas vere belov the current tentative threshold limit value for occupational exposures, dropped to 1/10 to 1/100 of this value in adjacent vork areas, and to 1/100 to 1/5000 of this in ambient air. The significance of the ambient air concentrations in terms of human health cannot be -8- t .1 0SZm'-'HiK6S I defined vlth current cpldemlologlc data. Although aabient air concentrations vere very low, one oust remember that inhalation Bay continue on a 2l*-hour basis, that some individuals Bay get s -y such &ore than the average, and that children aay be exposed, vith the potential of longer lifetime of retention. Even vlth these **#** , considerations , and our conviction that all unnecessary exposures ;V.fv .7-.'. , V: ' to asbestos should be prevented, the levels presently Beasured va i ' i *i >' -j r a y .- * cannot be regarded as constituting an emergency situation. ':.r ,| ;{*fr**V .vA. v 4*i'' ' . >1 * Prepared by: V, Clark Cooper, M.D. >; y J. LeRoy Balser, M.8. * Douglas P. Povler, K.8 -9-