Document 6BE2yK66krOGK45B7ywEjj6jd

- r * --J Mineral riser y.ir.u:'ac:urers ' Association , Inc. - i : c r z r. a v - v. c c - e r Associates /reiirisary Report cn Building vith Sprayed '.cturr. Air Stace . Analysis of Air Samples Collected Mineral Fiber FireprooSir.g lining i- a the o < ti w p . | * to r t ' *tJ luring the jperiod July 7. to July 9> 1970, air samples vers collected at tve points *Vitnir. the^air',aistriV\fti:on,s'sy%'t'n*of' *a*large*:'SanFrancisco office building. The purpose vas to make & preliminary assesrer.t of the pro'sa'oilitythat asbestos fibers vere oeinz added to the air stream in its passage over sprayed mineral fiber fireproofing. The fireproofing material had been applied to structural steel members of the building during its construction in 1$66. The portion of the air distribution system selected for this test supplies air to the 32nd to Ulst floors; the airsoving equipment is located on the l*2nd floor, vhich is entirely given over to mechanical support equipment. Air is supplied to the occupied aces cn these floors through enclosed sheet metal ducts partially ned vith fibrous glass. Air is returned through the spaces tveer. the structural and suspended ceilings on each floor. It conducted thence to a large return shaft leading to the -2nd cor mechanical room. Approximately 755 of the returned air epending on external temperature) is recirculated, the remainder discharged to the outside. The returning air is in contact vith rayed mir.eralfiber fireproofing during most of its passage back the mechanical room. Sampling and Analysis Air samples vere taken at tvo points, both vithin the ^2nd floor mechanical room. The first point ("Supply") vas immediately dovr.stream of the filter through vhich the combined recirculated and outride air pass before delivery to the occupied space of the building. The second point ("Return") vas the top opening of the return air shaft through vhich all returned air passes before its eva.ttual recirculation or discharge. Four air samples vere taker. t each sampling point as match ed pairs of samples; the sampl _g er'.cfs vere coincident at both location s. The time periods v ere : c - r. IcCO on July 7; 0900 - 1500 ar.d 1500 - 2000 on July 3; ar. d 9 OC - 1500 on July 9* All air s anples vere taken by draving air mm diam eter Mill ipore 0 rganic mem orar.e fii ters ( O.c. urn mean tore sire) at a flov r ate of 0.3 cubic feet per mo nut e . T h s filter hoi cers ver e placed in the moving air streams at pc i r. t s - here the linear air vei ocities m atched the filter face vel coiti e s v i t h in <- 25* . t n e cui; s m o _ c cr. * - e - for "'*o dczer=ir.5.tion oa::c:zos fleers. A portion of the- r.cnh----- I filter vos piece! cr. a microscope elide, cleared by the aaditicr. <- a drop cf a mounting medium matching the index of refraction of t.-.e filter,- cr.o covered vith a cover clip. The mounted filter voo then examined v i t h'phase contrast microscopy at a magnification of liey; ICC roneem microscopic fields (defined by a Pcrton eyetieco reticle^ vir: sc examined, and ail fibers counted and placed in sine cate^orie* The location of each fiber vac marled, and the slide vas transferred to the petrographic microscope, vhere (also at a magnification of -2CX) the fibers vere . identified. The identification in this case vis limited to deciding vhether or not the fiber in Question vac asbestos^^Jde^unbers ..of asbestog^fibers ^seen vere converted to concentrations, expressed in fibers pel*'"litero'f'^Vampled ~iir b^yVc*fc* talcing into account the area counted, the flow rate, and the sanding time. A secondary analysis vas the determination of the gravimetric concentrations cf all particular matter. The filters vere veighed it 0.C05 mg) before and after exposure; the change in veight vas divided by the number of cubic met'ers of air vhich had passed t the filters, and the results expressed as micrograms of particu per cubic meter of air. H M* All sample filters have been retained and are available for electron microscope analysis, if this becomes desirable. v P.esults !n Table I are shovn the results of the air sampling program The esults are shovn both as asbestos fibers per liter (f/1) an a as ctal particulate mass concentrations (ug/m"3). Asbestos Fibers and Total Particulate Concentrations ; j w a i. e i ! me j 7-7-"C i# i 1500 i . 0900 - IcCO - 1500 \ i * i-C-|v 1500 - 2000 C9C0 - 1500 1 Sup f/1 !.2 1-2 2.7 i i | 2.1 j i ^/=3 U 5 6 J "3 Setnr n ! f/1 ! ug/n i i\ c u -! i /! - i1 25 5.9 V'j ! j6.9 " ' t 6.9 '-| UO 1'f ! 1 i 20 ;t Co /i1 - 3:: us n ire0 :cr : ccr.p-.e~c , cer.tra:io::s the- suppl :e:.cer.:r?.::o:.s in tr.e air vr.icn 1 i z o r f i r e p r o o f i r. g s h o -* s a clear t r p - r rhn.t ve have see" in buildings r. conical viah this type 01' iirepreo ctistically significant vith alpha = rcbability that these results are a o reason to believe that further air yield results markedly different tha Outside air samples vers being taker. during the sane period covered in this report, at another sampling site near to th building. The "asbestoS'^fiber`concentrations found -therefore sindlar to those found here in the "Supply" samples and sig lover than the concentrations in the "Heturn" samples. e *<?- ' *v P* Ve must emphasise that this report is based on limited sampling on cue building system, and that extrapolation to other buildings, or istribution systems in vhich the air velocities may be ferent, is not warranted. Nevertheless , our preliminary on is that, in this building, asbestos fibers are being added to the air stream passing over sprayed,-mineral fiber fireproofing. - Report Prepared By: Douglas ?. Pevler, . 5 .