Document 31eyMz4MDdX1pawyJOJjbYoD
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3180 UtlYtA STHCt. T. lltltKUCY. CAtirCRMA 34701 UAiUNG AnonCSS: P.o. aox 773
July IS, 1970
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AS3CSTCS FISCR CGTiCENT HAT I OHS IW AIR FROR SPRAY riREPRCOTW
r PtAINTlFPS
OPCRATIGNS USIKC ZONOLITC PROOUCTS
11^< EnXilHlIinBnIT- '
i WRRGG--,1t5599(6S'
In order to dotorwino concent rat ions of airbomo esbastos during ond after the application of varmiculito-osbestos canont .eatcrials in tho fireproofing of structural stool, observations acre aado at thrao construction sitos in San Francisco on Kay 20, Kay 28 and Juno A, 1970. Consideration aas given to tho actual and potential exposures of (a) orknon carrying out the spray operation, (b) workers in allied tredos nearby, and (c) the general public.
Sites studied. Three spray operations were survoyedi (1) the Cebarcadero Center, ehoro hr. C. Connell was spray contractor; (2) tho P.C. and C. Headquarters euildlng, ahare tho spray contractor aa CAR Plastering, Inc. (hr. Rsseussan); and (3) the Hilton Toeers, shore Kr. C. Connell was also the contractor.
'
Hethods. Airborne fiber concentrations ware deteroinod by dreeing air through Kllllporo type AA filters, with 0.$*a eean pore si2e. Secples ears taken in the breathing zones (8z) of nan working with the notarial and at various locations surroundino the operations. Air flows ranged free 0.11 cubic feet per ninuta (cfa) in breathing
zones to 1.8 cfo in areas nore distant. Portions of the filters sera nountod on slldos, and the fibors in 100 nicroscopic fiolds counted, using phase contrast nicroscopy at a nagnification of 43Qx. The nusters of esbastos fibors soon sere convertod to concentrations, expressed in fibers per nillilitor of air, by taking into account the area countod, the flow rate, and the sanpling tine.
Results. '
Cnbercaderq Center - Mav 26. 1970. Spraying was being convicted on tho 41st floor of the 43-story building. The threa nan at work at this site sere all plasterors; there wero no hodcarriors. Tho plasterers novod their own stares but did not clean the area as thoy worked. The floor of tho work sito was covored to an oslinalod depth of two inchoa
with rebound and ovorsprayed fireproofing anterials. The gun froo which the ratarial was being applied was being operated et a relatively high air flow rata, resulting in considorablo rebound.
Saeplea wore taken (A) of tho air in tho broothlng zonos (CZ) of the gun operator and the non saving tho stngo from which tho operator was working; (t!) of tho oir in tho aroa surrounding tho spray operation! (C) of tho oir wuving through tho 43rd floor (2 floors cbovo tho spray
operation); (0) of tho air In tho breathing zono of tho lnvoatigatar
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!
os ho coved around thn spray operation (oquivnlunt to tlto exporore which might bo oxpcriuncud by n construction worker in tho an:.i)j (C) of tho air in tho breathing zono of tho mixer oporator working on tho gsauod floor (Tablo I).
TABLE 1 EMBARCADERO CENTER AIR SAMPLES
Sample liueber_____________
Asbestos fibers Area total f/nl f/nl (>5 un)
(A) 51 (A) *9 (A)
Spray operator's BZ
a ww
* " (Hold near bock, of head to protect face of filter)
7.96 2.63
3.56
6.5^ 2.18
3.18
*T (A) 22*9 (B)
Stage mover's BZ
1.86
Area near spray (1-50 feet dis tant, some dlreet spray on filter)0.030
1.55 ' 0.028
2250 (C) Background area, 13rd floor (air
(
flov past spray-encrusted drapes) 0.020
0.016
56 ()
Investigator's BZ
0.79
0.60
k8 (E)
Mixing Operator's BZ
0.775
0.710
Present tentative occupational threshold Halt value of 5 f/nl Is based oa fibers greater than 5 micrometers la length.
P C k C ?tiiloinn - S*nv 25. !970. A crow of 6, with two guns operating simultaneously, was ot work on tho 21st floor. Tho first iapression on arriving at tho work sits was of elesnlinoss and order. Tho hod-esrriars* when not aouing tho stages* were scraping tho floor near each stage* and coving tho accumulated robound and ovorspray firoproofing oaterial to a largo central pile for roooval. There wos a business-like atmos phere* and tho crew sppoored to bo officiant. It was noted that moving of the stages was accomplished* for tho most part* without request from tho gun oporator* but on the initiative of the hod-carricrs. Tho spray used here appeared to bo drier than at tho provioue site* end was being applied at a lower volocity and flow rata. The finished sprayed surface appeared'to be soeowhat roughor* but tho build-up from leaving tho gun in one place too long was less* loading to a moro comfortable working pneo for tho oporator and less direct robound on his face end porson, Samplos wore takoni (A) in tho breathing zono of tho gun operator! (0) in tho breathing zono of tho invostlgotor
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(equivalent to tho breathing zona oxposuro of lha hod-carriers; (C) upoind and doemind (appruxioatoly) of tho stages* in tho gonoral area of tho stages; (0) in tho broathlng zones of tha sixer operators; (C) in tho geHWoi aroa of tho Mixing operations; (f) ono floor beloe tiiw pray operations; and (C) in tho genoroi area of spray operations (Table II),
Saaple Rusher
53 (A) 1 (A)
55 (B) 2 (C) 3 (C)
60 (D) 52 (> 59 (S> 61 (Z) 2lb? (P) '
1 (C)
5 (C) 211<9 (C)
TABU II , PCtI AIR SAMPLES
Area Spray operator's BZ
Asbestos Fiber# Total f/al
4 3.32
2.91
BZ of investigatorclose to spray stage* vailing vith hod-carrier
3.15 0.16
2.6b
a %.
0.1b
Area* bo feet upvind of single
stage Tair flov variable)
0.13
e
0.11-
Area* bo feet dovnvlnd of stage
(air flow variable)
0.25
0.23
Mixing operator's BZ (vlnd avay froa)
0.30
0.b*2
Mixing operator's BZ (vlnd tovard)
Mixing area (betveea tvo mixing operators)
Mixing area (betveea tvo airing operators)
l.b2 1.09 1*3*"
1.25 0.98 1.1b
Background* 1 floor belov spray operations* aost air flov not through the building to filter* but variable.
0.01b
0.011
Area* betveea tvo stages (current to'puap eut off at variable tlaes* total flov through filter unecrtaln) 0.036
Area* 3 feet froa stages (2)
0.071
0.036
0.061
Area, 35 feet froa stage* (air flov in area unecrtaln and variable) 0.36
0.3b
Present occupational threshold Halt value of 5 f/al la based on fibers greater than 5 aleroaetere in length*
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HI Moo Town - Jiny 4, 17fl. Spray operation-; nero underway on the 2lal floor of this UuiltJinq. Thoro was a stnndy nvslorly nine ihruugh the building. A second r,un croo as spraying --lairoays on Iho'SSih and 31st floo^o- The job site was clean and ortJurly in appearance (considorinc* tho nature of the operation), and the hod-enrrior eas cleaning
the floor as the stage ess oovod. The sir flow rate and rato of appli cation oas sooanhnt higher than on the P C 1 C Job, but not as high as on tho first Job. Tho oixing arcs eps in tho bosceont of the building, but there was o good floe of air. through tho oixing area* secondary to tho high Bind speeds aloft. Air scopies wore taken in (A) the spray operator's breathing zone, (0) the hoC-garrier's breathing zone, (C) upolnd and tiaranoini of the area of the spray stags, (0) on the upind side of tho building on tho 35th floor (tho upporoost levol at ehich continuous flooring hod boon installed),' (C) doonolnd of tho 17th floor, (f) in tho oixing operator's breathing zone, and (C) in tho aroa of tho oixing operation (Table III).
TAOLE III HILTO* TOWERS AIH SAMPLES
Staple Huaber
Ares
Asbestos total f/nl
62 (A) 6k (B) 226b (C) 2262 (C) 73 (D)
Spray operator's BE
( 2.VS
Hod Carrier's BE
0.V9
Vpvlad of stags
0.0007
Bovsvlad of stage
0.01b?
Opvind of 35th floor - Background
(Prob. aon-lso-klnotle flow at
aoao
filter facet validity aa a
aeoa
final aeaaure of fiber baekgrouad
level!)
2.20 0.33 0.0007 0.0137
aoae aeon
2259 (E)
57 (P) 69 (P) 63 (C)
Sovavlad of 17th floor (four floors belov spray operators)
Xlxlag operator's BE Mlxlag operator's BE Mixing Aroa
* Soo note tablas 1 and IX.
0.0017
1.61 0.55 0.V3
0.0017
l.bS 0.50 0.38
Aobfont Afr S-roHna. Air saoplas wore taken in upolnd ana down wind street areas around tho Hilton Toeora on Juno 23, 1970. Puopo drawing sir through Killlporo filters at floe rutos froa 0.057 to .11 cubic foot per oinuto ooro used. A total of 0 saoplos wore takonj A upolnd and 4 dwniind, 2 upolnd and 2 doonolnd saoplos ooro taken in the corning and afternoon (Tablo IV). Tho sooplos in the upolnd sroa (oast of the hotel) ooro of too kindsi stationary samples (in
parking lot of the SOO block of leavoneorth Street), and "wowing"
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saaplos (in tho gannral arnn bnuncJod by Turk, Jonns* Post, and Hyde streets). Tho moving settles ooro tni.en by an investigator scaring a riltor bflldar, The domnmind samp1os aero token in tha sane nay. Stationary sarploo ooro taken at too locations: tho ooming sarplo froa an open oindoo (2nd floor lavol) at 150 Poooll Stroot and tho afternoon saaple on tho roof of a parking lot offico one block ooat of the Hilton, ("lie sowing saaplos oere takon in Vho area bounded by Carkot, Grant, Coary and Cason streots.)
TA2LC IV
Morning Stationery Moving
Air Sampling Results (fibera/el)
*
Upviad
0.02b 0.01b
Sensitivity #
0.00$
o.ops
Dovnvind Sensitivity
0.016 0.0b2
0.016 0.009
Afteraooa
' Stationary
0.077
0.009
0.01$
0.00$
Movies
0.009
0.00$
0.00$
0.00$
on .filter
* Unian fiber concentration As 1 fiber per 100 fields observed.
Sensitivity is inversely proportional to the. volumo of air passed
through tho filter.
Discussion. Tha occupational exposures to spray operators sere not obovo tho currently recoaasndsd threshold liait valuas for asbestos exposures, ohich have recently been recommended for reduction to 5 f /al (fibers over S oicrooetere in length) based on a tico-meightod avorage over an 6 hour oork day, S days a seek. Only one sacple higher than this level see found. The side variability is normal for this type of operation. Scvorthelooa, there is-little margin of safety and the potential risk free asbestos inhalation is such that os eould rocoaeend that exposures be reduced even further. Concentrations droppod off rapidly in the odjacont areas and may reach levels of the aabiont air.
Background or aabiont air concentrations ranged froa less than 1 fiber per liter of air (upaind high in Hilton Toners) to 77 fibers per liter at ground level upaind at Hilton Toners. Tho variability reflected tho variety of alnd conditions during tho study, aultiple construction projects 1a tha dosntoan area, as aoll os inherent saaplina variations. There is no eoy to estimate the contribution or the fireproofing spray Jobs being studied to tho overall background fiber level in Son Trsncisso. In other studies. In Cast Cay, so havo found tho average asbestos fibor concentrations to bo approximately 1 f/litar, but sometimes going as high as 12 f/llter.
Since confusion say arise fros using dlfforent units to describe concentrations of fihors in sork arose and in aabiont sir, thp ranges of concentrations expressed uniformly as fibers per liter have boon grouped in Table V.
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TAOLC V CONCEPTRAT ICES Cf ASCESTOS ritCftS IK AIR CXPRCSSCO 10 fJCERS Ftft LITCft
Value or site
ftannet fIl*r*/l itnr
Proposed occupational threshold licit value (ACCIH).......... ..
5,000*
Spray erea breathing zones Cun nporator............................ Stage cover................................... Mixing operator.................
Adjacent cork areas on sues floor.
Pork sreas on other floors.....
Vicinity of buildings being sprayed. Upeind..................... Dou--ind..................... ................
2,400 - 7,960 490 - 1,860
. S00 - 1*610
1 - 360
<1 - 14-
95-
77 42
Aabient sir in Bay Area................
<1 - 12
Fibers over 5 ua in length
other values not corrected for this.
The threshold Unit value for occupational exposures proposed by the American Conference of Covemoentsl Industrial Hygienists has been included for reference (TLV), Exposures of spray cre*s averaged be lea the TLV; eorkars in adjacent areas of the saae buildings ears exposed to concentrations free 1/10 to 1/5000 of this values individuals on other floors of the buildings and in the building vicinities had transitory exposures ranging froa 1/100 to 1/5000 of the TLV* actlent
air levels in the Say Area aero froo 1/500 to less than 1/5000 of this value. Direct extrapolation froo reeoceondod occupational lsvals to the co--unity is certainly not Justified* but in tho absence of aabient air or eoission standards* the TLV provides a point of rafe> renca. .It does not take into account 24-hour-a-day exposures* or tho fact than children aay ba exposed eith the potential for a longer lifeti-- of retention. Even eith these reservations* tho concentrations --soured to date in aabient sir do not sppoar alarainq. Since unnocos sary exposures to asbestos should be prevented and co-unity contami nation kept to a ninicuo, -- encourage all practicable caesuras te contain aotsrialo and prevent fiber dissecination^
Prepared byt d. Clark Cooper* M.D. J. Loroy Salrsr* M.S. Douglas P. foelur* M.S.
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