Document DDBVgGqV7gj2QXwOjB7ZELDao

FILE NAME: WR Grace (WRG) DATE: July 15, 1970 DOC#: WRG223 DOCUMENT DESCRIPTION: 1970 consultant report on asbestos fiber concentrations in air from spray fireproofing. Irv ln i R. Td Sirih w , M. 0. W. CUrte Coopr, M. O. *7ci&te/icicu-- d cay~` 'i /4<^cciatc 2180 MILVIA STREET, BERKELEY, CALIFORNIA 94701 MAILING ADDRESS: P.O. BOX 772 (Ml July 15, 1970 ASBESTOS TIBER CONCENTRATIONS IN AIR FROM SPRAY FIREPROOFING OPERATIONS USING ZONCLITE PRODUCTS In order to determino concentrations of airborne asbestos during and after the application of vormiculite-asbestos cement materials in the fireproofing of structural steel, observations were made at three construction sites in San Francisco on flay 26, fay 28 and June A, 1970. Consideration was given to the actual and potential exposures of (a) workmen carrying out the spray operation, (b) workers in allied trades nearby, and (c) the general public. Sites studied. Three spray operations were surv.oyed: (l) thg Embarcadero Center, where Mr. G. Connell was spray contractor; (2) the P.C. and E. Headquarters Building, where the spray contractor was C R Plastering, Inc. (fr. Rasmussen); and (3) the Hilton Towers, where fir. G. Connell was also the contractor. Methods. Airborne fiber concentrations wore determined by drawing eir through hiilipore type AA filters, with O.g/tm mean pore size. Samples ware taken in the breathing zones (Cz) of man working with the material and at various locations surrounding the ooorations. Air flows ranged from 0,11 cubic feet per minute (cfm) in breathing zones to 1.8 cfm in areas more distant. Portions of the filters were mounted on slides, and the fibers in ICO microscopic fields counted, using phase contrast microscopy at a maonification of 430x. The numbers of asbestos fibers seen were converted to concentrations, expressed in fibers par milliliter of air, by taking into account the area counted, the flow rats, and the sampling time. Results. Embarcadero Center - ft*ay 26, 1970. Spraying was being conducted on tho 1st floor of the 43-story building. The three men at work at this site were all plasterers; there were no hodcarriers. The plasterer moved their own stages cut did not clean the area as they worked. The floor of the work site was covered to an estimated depth of two inches with rebound and oversprayed fireproofing materials. The gun from which the material was being applied was being operated at a relatively high air flow rate, resulting in considerable rebound. Samples wero taken (A) of tho air in tho breathing zones (GZ) of the gun operator and the man moving the stage from which the operator was working; (8) of the air in tho area surrounding tho spray operation; (C) of tho air moving through the 43rd floor (2 floor3 above the spray operation); (D) of the air in tho breathing zono of tho investigator as ha moved around tho spray oporation (equivalent to tho oxposuro which might be expcrioncod by a construction worker in tho area); (El) of tho air in tho breathing zona of tho mixer operator working on tho ground floor (Tablo I), TADLE I EMBARCADERO CENTER AIR SAMPLES Sample Asbestos fibers N u m b e r _______________ Ar e a _________________________ to ta l f/ml f/ml uni* 5** (A) 51 (A) 1*9 (A) 1*7 (A) 221+9 (3) 2250 (C) 56 (D) 1*8 (E) Spray operator's BZ M ft tl 7.9 6 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 B a c k g r o u n d area , l+3rd fl oo r (air flow past spray-encrusted drapes) 0.020 Investigator's BZ 0.79 Mixing Operator's BZ 0.775 6 . 5 1* 2.18 3.18 1.55 ' 0.028 0.016 0.60 0.710 * P r e s e n t t e n t a t i v e o c c u p a t i o n a l t h r e s h o l d limit v a l u e of 5 f/ml is based on fibers greater than 5 micrometers in length. P G i: c. ^urldinn - May 29, 1970. A crew of 6, with two quns operating simultaneously, was at work on the 21st floor. The first impression on arriving at the work site was of cleanliness and order. Tho hod-carriers, when not moving tho stages, were scraping the floor near each stage, and moving the accumulated rebound and uvorspray fireproofing material to a large central pile for removal. There was a business-like atmos phere, and the crew appeared to be efficient. It was noted that moving of the stages was accomplished, for the most part, without request from the gun operator, but on the initiative of the hod-carriers. The spray used here appeared to be drier than at tho previous site, and was being applied at a lower velocity and flow rate. Tho finished sprayed surface appoared'to be somewhat rougher, but tho build-up from leaving the gun in one place too long wa3 less, leading to a more comfortable working pace for the oporator and less direct robound on his face and person. Samples wore takon (A) in tho breathing zone of the gun operator; (B) In the breathing zono of the investigator - 2- K i];;on Townr*-. - Jung h, ]n7H, Spray oncratinns were underway on the 21st floor or' this building. There tins a steady westerly wind through the building, A socond gun crow was snrayinn stairways on tho'33th and 31st floor:;. Tho job site was clean and orderly in appearance (consi- dorinc tho -i.atura of tho operation;, and the hod-carrier was cleaning the floor as the stage was moved. The air flow rato and rate of appli cation was somewhat higher than on the P G <1 E .job, but not as nigh as on tho first job. Tho mixing area u;as in the boscrr.ont of tho building, but there was a nood flow of air through the mixing area, secondary to the high wind speeds aloft. Air samples wore taken in (A) the spray operator's breathing zono, ('.:) the hod-r.arricr's breathing rone, (C; upwind and downwind of the area of tho sarav stage, (D) on the up wind side of the buildine on the 35th floor (the uppermost level at ' which continuous flooring had bean installed),' (E) downwind of the 17th floor, (F) in the mixing operator's breathing zone, and (-G) in the area of the mixing operation (Table III). TATIE III ..... " HILTOH TOWERS AIR SAMPLES Sample tnber 62 (A) 6 b (3) 226b (C) 22 62 (C) 73 (D) Area Asbestos to ta l f/nl f /ni M > 5 u- CO OJ Spray operator's BZ Hod Carrier's BZ 1 0.b9 Upwind of stage 0.0007 Downwind of stage 0 .Olb 7 Upwind of 35th floor - Background (Prob. no n - i s o - k i n e t i c flow at none f i l t e r face; v a l i d i t y as a seen final measure of fiber b ackground level?) 2.20 0.33 0.0007 0.0137 none seen 2259 (E) 57 (F) 69 (E ) 63 (G) Downwind of 17th floor (four floors below spray operators) Mi xi ng operator's BZ Mixing operator's 3Z Mixing Area 0.0017 1.61 0.55 ' 0 .b3 O u> Co 0.0017 1 b 5 0.50 * See note tables I and II. Ambient Air Sn~nlInn. Air samples were taken in upwind ana down wind street areas around the Hilton Towers on June 23, 1970. Pumps drawing air through hillinoro filters at flow ratos from 0,057 to ,11 cubic feet per minute wore used, A total of 0 samples wars taken; A upwind and A downwind, 2 upwind and 2 downwind samples were taken in the morning and afternoon (Table I'J), Tho sam.plco in the upwind area (west of tha hotel) were of two kinds stationary samples (in parking lot of the 500 block of Leavenworth Stroet), and "moving" -A- camples (in tho general a r m bnundod by Turk, Jones, Post, and Hyde streots). The moving samples wore taken by ran investigator woering a filter holder. Tha downwind samples wore taken in tha same way. Stationary samples v;cro taken at two locations: the morning sample from an open window (2nd floor level) at 1'jO Powell Street and tha afternoon sample on tha roof of a parking lot office one block west of the Hilton. ( ino moving samples were taken in the area bounded by market, Grant, Geary and Mason streets.) ' ' ' TABLE IV ' Morning Stationary Moving Upvind Air Sampling Results (fibers/ml) ' * Sensitivity Downwind Sensitivity 0.02U 0.01.1+ 0.005 0.005 0.016 0 .Qk2 0.016 0.009 Afternoon Stationary 0.077 0.009 0.015 ' 0,005 Moving 0.009 0.005 0.005 0.005 on filter * Minimum fiber concentration/is 1 fiber per ICO fields observed. Sensitivity i s inversely proportional to the volume of air passed tnrouah the filtcr. ^i_si^rvr_i:T_ri, Tha occupational exposures to spray oparators wars not above the currently recommended threshold limit values for asbestos exposures, which nave recently been recommended for reduction to 5 f ./ml (fibers over 5 micrometers in length) based on a time-weighted average over an 8 hour work day, 5 days a week. Only one sample higher than this level was found. The wide variability is normal for this type of operation, i.'svertheless, there is little margin of safety and tnc potential risk from asbestos inhalation is such that we would recommend that exposures be reduced even further. Concentrations dropped off rapidly in the adjacent areas and may reach levels of the ancient air. Background or ambient air concentrations ranged from lass than 1 fiber per liter of air (upvdnd 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 tho study, multiple construction projects in the downtown area, as well as inherent sampling variations. There is no way to estimate tho contribution of the fireproofing spray jobs being studied to the overall background fiber level in San francisco. In other studies, in East Cay, wo have found the average asbestos fiber concentrations to bo approximately 1 f/litcr, but somotimes going as high as 12 f/liter. Since confusion may ariso from using different units to describe . concentrations of fibers in work areas and in ambient air, tho ranges of concentrations expressed uniformly us fibers per liter have boon grouped in Tablo V. TABLE V CONCENTRATIONS OF ASBESTOS FIBERS IN AIR EXPRESSED IN FIBERS PER LITER Va 1uo or sits________________ Rgnnn :_fiher-./1ihnr Proposed occupational threshold limit value (AEG IK)....... 5,000* Spray crew breathing zones Cun operator....... . Stage mover....... . Mixing operator.... . Adjacent work areas on same floor. 2,480 - 7,950 490 m 1,860 - . 500 - 1,610 t 1 - 360 w ork areas on other floors,,.,. <1 - 14 Vicinity of buildings being sprayed. Upwind.............. ...... - Downwind...... ........... , 9- 77 5 - 42 Ambient air in Say Area....... <1 12 Fibers over 5 cm in length uther values not corrected for this. The threshold U n i t value for occupational exposures proposed by the Anerica.n Conference of Governmental Industrial Hygienists has bsen included for reference (TLV). Exposures of spray crews averaged below the TLV; workers in adjacent areas of the same buildings were exposed to concentrations from 1/10 to i/5000 of this value; individuals on other floors of the buildings and in the building vicinities had transitory exposures ranging from l/lOO to 1/5000 of the TLV; ambient air levels in the Bay Area were from 1/5C0 to less than 1/5000 of this value. Direct extrapolation from recommended occupational levels to the community is certainly net justified, but in the absence of ambient air or emission standards, the TLV provides a point of refe rence, It does not take into account 24-hour-a-day exposures, or the fact than children may be exposed with tho potential for a longer life time of retention. Even with these reservations, the concentrations measured to date in ambient air do not appear alarming. Since unnecos sary exposures to asbestos should be prevented and community contami nation kept to a minimum, we encourage all practicable measures to contain materials and prevent fiber dissemination. Proparcd by: W, Clark Ccopor, M.D. J, Leroy Calzar, <7.,S, > Douglas P, Fowlor, F.S, - 6-