Document Bv8BV7mxYMn5rMDjBZVJewXOE

Evaluation of Ambient Air Quality by Personnel Monitoring Author: A. L. Linch Consultant Environmental Health Everett, Pennsylvania published by: CRC Press, Inc. 18901 Cranwood Parkway, Cleveland, Ohio 44128 ucc 035040 f>iitngane$e, aluminum, iron, titanium, nickel, zinc, silicon, sulfur, sodium, calcium, bromine, chlorine, potassium, and copper. Samples were collected on Millipore membrane filters which were dissolved in acetone in preparation for analysis. Calibration curves were developed using external standards and taking into account the variation in spectral response as the dust layer thickness varies. Back ground (blank) corrections were included. Standard samples for quantitative emission spectrography were perpared by mixing spectro scopically pure oxides of the elements with Ringsdorff graphite and gallium oxide as an internal standard. An aliquot of the centrifuged particulate was also mixed with the graphitegallium oxide standard. Comparison of the two methods indicated X-ray fluorescence was a valid technique for direct analysis of dusts.4*c Nondispersive X-ray fluorescence analysis has been applied to lead and bromine aerosols collected in downtown Berkeley, California. The technique employed was nondestructive to the filter paper collection medium and required only 2 min/analysis. The equipment was easily rendered portable and could be carried in the field. The ratio of bromine/lead appeared to be significantly different from location to location.4 *d 3. Neutron Activation Although rather elaborate equipment for activating and nuclear decay counting is required, the extreme sensitivity and reliability of this direct approach justifies consideration. By means of gamma ray* spectrometry and computer tech niques, sodium, manganese, chlorine, vanadium, aluminum, bromine, copper, and indium can be determined simultaneously. Polytetrafluoroethylene (PTFE) filters were particularly well suited for sample collection (lowest chlorine con tent).4 * * An even greater number of elements that can be detected by this technique were described recently by Gray and his co-workers.4 *f 2. Cascade CoBecton - Respirable Fraction Probably the best presentation of "respirable" dust sampling and the physiological basis for the selection of appropriate filtration devices was presented by Morton Lippmann*0 for the interim `Guide for Respirable Mass Sampling" prepared by the AJHA Aerosol Technology Committee52 and later included in the ACGIH's Air Sampling Instruments for Evaluation of Atmospheric Con taminants.1 Excerpts which follow are presented by permission of the copyright holder. a. Samplingfor Respiratory Hazard Evaluation Air sampling technique* have been used to obtain information for a variety of purposes. The discussion to follow concerns the specific purpose of nmpting for the evaluation of the toxicological inmR arizing from the inhalation of airborne particles. Ah sampling technique* used to obtain information for other purposes, e.g., performance testing of ventilation systems and air cleaners, contamination monitoring fat so-called "white'* or "dean" room operation, and for beak scientific studies of atmospheric reaction*, composition, and capacity for pollutant dispersion may differ, and are beyond the acope of thi* discussion. If the objective is to obtain information on the nature and magnitude of the potential health hazard resulting from the inhalation of airborne particles, the techniques must be capable of providing data on the contaminant oonccntntion within the sue range which reaches the critical organ for toxic action. In othar words, the choice of methods must be bated on a recognition of the size-selecting characteristics of the human respiratory tract, fai addition to the usual parameters affecting the election of methods, eg., the physical ttnfatatiow of the collection process, and the senfathity and specificity of the analytical procedures. There haa beea an fascrearing recognition at te impostanre vt th* rekatire aaapifaag of nugbaits deat W meant jiws. after lirafare, fa* which thf fan trfertfa^ danfanMn at fata hnaw reapimtocy tract me hvgs^g ignored. The only standard method which provided a meant for discriminating against non-respinble particles was the impinges sampling-tight field counting technique for pneumoconiosis producing dusts. The GreenburgSmith impinges, developed fat 1922-25 through the cooperative efforts of the U.S. Bureau of Mines, U.S. Public Health Service, and the American Society of Hating and Ventilating Engineers,' end the midget impfaiger, developed fat 192$ by the Bureau of Mines,' efficiently collect particles larger than about micron in a liquid medium. The samples are analyzed by counting the particles which settle to the bottom of a wet counting cell and are visible when viewed through a 10X objective lens. PirtMes iatyw than 10w obtarvafa during the nouat are rejaatad by many industrial hygiarfastt aa "bow resphabtaT In the alternative approach of gravimetric analysis of the total airborne particulate sample, these is no practical way to discriminate against the oversized particles. b. Regional Deposition, Clearance, and Dose The hazard from airborne particles varies with their physical, chemical and/or biological properties. There properties wSl determine the fate of the particles and their interactions with the host after they are deposited. A basic consideration it that this fate fas any given individual varies greatly with the fate of deposition whim the respiratory tract. There are a number of major subdivision* wfabhi the 141 and doeumentstion for the "Interim Guid# on `Rmphable' Mm SimpUr*"*' of the AIHA Aeroiol Technology Committee. I Measurement ofMass Concentrations within Size Graded Aerosol Fractions Since the doee from inhaled torraet* is dependent on the regional depodthut, which ia dependent on paitide too, the beet doae eathnatee for a material whoee toxicity b proportional to abeorbed mam can be derived from a knowledge of the mam concentrations within virions size ranges. Such information can be obtained fat sevenl ways; (1) by separating the aerosol into nze fractions oonespoTKting to anticipated regional deposition during the process of collection; (2) by mating a size distribution analyds of the airborne aerosol, s_g_, with a conifuge, cascade impactor, fight scattering aerosol spectrometer, etc.; and (3) by making a die distribution analysb of a collected sample. The most rclabie information can be obtained using method* hi which the aerosol it Auctioned on the bests at aerodynamic diemeters in much the tame manner at it is fractionated within the respiratory tract. Thus, differ ence! in particle shape and density are automatically compensated for. Light scattering instruments which sort the pulses resulting from the nattered fight from individual particles enn provide information on the distribution of airborne particle diameters. In converting this information to a size-mass distribution, an avenge particle density must be assumed. Furthermore, the accuracy of the diameter distribution it dependent on the particle dupe, mdex of refraction and surface roughness. For example, Whitby and Vomela report that for India Ink particles, which absorb light and have a rough surface, the indicated size was 1/2 to 1/S of the true size for the three different instrument designs tested. Further opportunities for error arise when the size distribution analysis b performed on collected samples. It is almost imponibta to examine the sample in the original state of dispersion. Thus, particles which were unitary in the ait may be analyzed as aggregates and vice versa. Furthermore, perticle* analyzed by microscopy will be graded by a linear dimension or by projected area dnmeter, and these are normally larger than the true average diameter. f. Standards and Criteria for Respirable Dust Samples British Medical Research Counci (MRC) - In 1952, the British Medical Research Council adopted a definition of "lespfeibk dust'* applicable to pneumoconiosis prodnemg dusts. It defined respirable dust as that reaching the alveofi. The BMRC selected the horizontal elutriator at a practical size selector, defined retpbabto dust as that passing an ideal horizontal dutrutor, and selected the dutriator cut-off to provide the best match to experi mental lung deposition data. The same standard waa adopted by the Johannesburg}! International Conference on Pneumoconiosis in 1959. In order to implement these recommendations, it was specified that: 1. For purposes of estimating inborn* dust to its rabtion to pneumoconiorit, samples for comporittona! analysis, or for assessment of concen tration by a bulk measurement such as that of mam of surface area, should represent only the `retperabk' fraction of the cloud. 2. The Tetpirable' sample should be separated from the cloud whic the particles are airborne end In their original state of dispersion. 3. The `respirable fraction1 b to be defined in terms of the free felling speed of the particles, by the equation C/C0 l-f/fc, when C end C0 era the concentrations of particles of falling speed f hi the `respirable' fraction and in the whole doud, respectively, and fe b a constant equal to twice the falling qseed in air of a sphere of unit density 5m in diameter. A umpfing device which meets these requirements would have e mmpiing efficiency vs. size curve suggested by Davies.* * It b ifiuttiated in Figure 11.5 end defined as follows: % Deposition -- 10 20 Diam. (m) - 2J 3.2 (for spheres of unit density) 30 40 50 60 TO 80 90 3.9 4.5 5.0 55 5.9 6.3 6.9 100 7.1 U5. Atomic Energy fnmmbiinn (AEC) - A second standard, rttihlbhad to January 1961 at a meeting sponsored by the AEC Office of ffcalU and Safety,*1 defined "Respirable Dust" at that portion of the inhaled dub which penetrates to tire noo-cflfctod portions of the lung. Tbit application of the concepts of retpbabb dust and concomitant sslrotivs tempting was totended only for "insoluble" pertidee which exhibit prolonpd retention to the lung. It was not intended to include dusts which have an appreciable solubility in body fluids end those which are primarily chemical intoxicants.' Withhi these restric tion*, "ratpbabk dust" was defined as folowt (Figure II.7): hrtide Size vs. Respirtbility Siae*0) * Respirable - 10 5 3.5 2.5 2 0 25 50 75 100 *Slaee referred to ere equivalent to an aerodynamic diameter having the properties of a unit density sphere. 143 ucc 035042 sampling concepts to otba toxk dusts ad ll relsbocs between respirable dust concentrations and accepted standards such as the ACGIH Threshold Limit Vshies (TLV*s) are more complicated. Unlike (ha MPC.'i fos radioisotopes, which are based on calculation, most TLVs are bated on animal and human exposure experience. Thus, even if the data on which there standards were based could be retted to the perticta die of the dud involved, which unfortunately h unhkety, there would probably be a different correction factor for each TLV, rather than a uniform (actor such ss 0.25. f V FIGURE II.7. Aerodynamic particle size at unit density - respirable mass deposition curve. (From Lippmann, M., Air Sampling Instruments for Evaluation of Atmospheric Contaminants. 4th cd., ACGIH, Cincinnati, O,, 1972. With permission.) American Conference of Governmental Industrial Hygienists (ACGIH) - The application of respirable dust Despite the enormity of the task of allemativt or revised TLVs baaed on "respirible" dull concentrations, ACGIH has made a start. At the amusd meeting in St. Louis, Missouri on May 13, IMS, ACGIH announced'7 in the* "Nooca of intended Changes" alternate mass concentration TLV*s fee quarts, cristobalite and trydymite (three forms of crystalline free silica) to supplement the TLVs based on particle count concentrations. For quarts, the alternative mass values proposed are "1. for respirable dust in mg/M': lOmg/M* % Respirable Quartz + 2 Note: Both concentration and % Quartz for the application of this limit are to be determined from the fraction passing a size-selector with the following character istics: Aerodynamic Diameter (u) (unit density sphere) % Passing Selector 2.0 90 2.5 75 3.5 50 5.0 25 10 0 "2. for 'total dust* respirable and nonrespirable:< 30 mg/M* % Quartz + 3 For both cristobalite and tridymite: Use one-half the value calculated from the count or mass formulae for quartz." >L y{'- ' It can be seen that the size-selector characteristic specified in the ACGIH standard. is almost identical to that of the AEC, differing only at 2u, where it allows for 90% passing the first stage collector instead of 100%. The difference appears to be s recognition of characteristics of real particle separators. For practical purposes, the two standards miy be considered equivalent. The proposed mass concentration limits ware obtained by a comparison of simultaneous impingcr and sizeselective samples collected in the Vermont granite sheds." Since the original impinger sampling and micro scopic particle counting standards were based on epidemiological investigations which had been performed 3 to 4 decades earlier in some of the same granite cutting sheds, it was possible to make a valid comparison of "respirable" mats and particle count. The U.S. Department of Labor has adopted the ACGIH Mte-salectac criteria for resphable dust and extended its application to coal dust and Inst or nuisance dust In their revved Safety and Health Standards fat ' Federal Supply Contracts published in the Federal Register,' * the ACGIH quartz, tridymite, and cristobalite were adopted along with the following rentable dust' limits: Coal Dust (Respirable fraction last than 5% SiO,) Inert or Nuisance Dust Respirable Fraction J10 meUS' , 15 MFPCF or 5 m$/U* <30 MFFCF or 10 mg/M*)*. 144 Evaluation ofA mbieni A ir Quality by Personnel Monitoring .Jf ucc 035043 Discusnoa of standards fat respkmbility - tonally, there ire two simpler icceptincc curves described bi the preceding ifanniinn, and they here simflii, but not characteristics. This it illustrated in Figure II.5. The thapea of the curvea differ beau* they are bared on different typee of collectors. The BMRC curre was chosen to give the beet fit between the calculated characteristim of an ideal horizontal chitriator and hint deposition data, while the AEC curve was patterned mate directly after the Brown, et aL** upper respiratory tract deportion data and is simulated by the seperation characteristics of cyclone type collectors. In most field rtuations, where the geometric standard deviation (o,) of the particle rise distribution it greater than two, samples collected with instruments meeting either criterion will be comparable. Far example, Mercer calculated the predicted pulmonary (alveolar) deposition accordmg to the 1CRP Tart Group deportion model*1 for a tidal volume of 1450 cm* and aeiosolwwtth 1J < e( < 4. He found that a sampler meeting the BMRC acceptance curve would have about 10% more penetration than a ampler meeting the AEC curve.** The goal of obtaining air concentration data related to health hazard can be approached in mranl ways For "insoluble" dusts, two-stage samplers couriering of a precollector, with a cut-off characteristic like that of the upper respiratory tract, and an efficient second stage can provide the desired information with minimal sampling and analytical effort. For other toxic materials, or for aerosols where the contaminant of interest is a mince mass constituent, it may be necessary to obtain the overall size-mass distribution in ordw to determine the mass concentration in different size ranges appropriate to the rites of toxic action. Since the ''respirable" dust standards outlined in the preceding section were intended for "insoluble" dusts, most of the samplers developed to satisfy their criteria have been relatively ample two-stage devices. In recent years, multi-stage samplers designed to simulate deposi tion within more restricted subdivisions of the respiratory tract have .been developed. These and other miritbttaga samplers will be discussed in the sections to follow. k. Two-Stage "Respirable"Dust Sampler* A two-stage respirable dust sampler consists of a first stage whose collection efficiency falli from very high to very low si the aerodynamic particle rize decreases from 10 to` 2m, and a second stage with high collection efficiency fat all partide sizes. Horizontal riutriaton and cyclones have bewa most widriy used as first stage collectors, while Stats have beat used as the second stage in roost two-stage samplers. Cyclones... can be operated ia any orientation without sigaifleart change ia their collection charseteris tics.* * The only precaution necessary is to avoid turning them upside down dosing or after sampling, which could cause duet flora the eyelose to CsD onto the Altar or out through tbs inlet. This independence of orientation, combined with their eraHer physical size at comparable flowrates, arc [rie} among the reasons that most of the recent taro-stage personal sampler designs have been built around miniature cydones at the prwcoDectors. These templets, combined with filter collectors as the second sttge end newly developed miniiture battery powered air pumps are small and light enough to be worn throughout a work shift. Most of the miniature battery powered pumps are diaphragm or piston type sir movers snd therefore produce a pulsating flow. This would surest to render them unsuitable foe puffing air through pre-collectors whose collection characteristics tie flowrate dependent The BCIRA cyclone of ffiggins and Dewel** is equipped with a pulsation damps' m order to overcome this problem. However, the problem may not be aa severe si it appears at first glance, at leut for thore applications when the parameter of interest is the "respirable" mass measered on the second stage. Knight and Uctitl* > have demonstrated that variations in airflow are corrected to some extent by changes in cyclone collection efficiency. For non-flbrous test aerosols, including mica and silica, there was ereentirty no change in the mass collected on the filter for flewratre between 1.3 and 2.65 Ipm. Aa the flowrate increases, the aerosol mats entering the cyclone increases proportionaBy, but so apparently does the collection efficiency. In an dutriator, the effect worid be the opposite; an increase in sampling rate would result in an increase in penetration to the filter. * Many of the cyclone pre-coDectora were initialy cstibrated tiring polytrisperss test aerosols of inugriariy shaped particles. The crevet of collection efficiency vs. sias, pabllehed by Lippmenn end Hurls** end Hyitt, et aL,* ' were determined from the comparison of the partick rire distribution analyses of up and downstream sampiea made by optical microscopic measurements. More recent cairbratioas swing spherical test aerosols or irregular pertides with measured terminal settling velocities have indicated that the diameters were overestimated in the original calibration. Foe example, the 10 mm nylon cyclone described by Dppmsna end Harris** si having collection characteris tics dosriy matching tha AEC acceptance curve at 2.1 lpm, has been recalibreted by Sutton,** snd Knuth,** Tomb and Raymond1" and Ettingcr and Royer.** Sutton, using polydispene lacquer spheres whose ternsnel settling velocity distributions he measured with e TimbreA*1 spectrometer before entering and after pene trating the cyclone, reported that the cyclone matched the AEC curve at 2.0 Ipm. Knuth twed monodieperee polystyrene Mtex end ferric oxide spheres whose terminal settling velodtiei were matured with an eiutriator tube,* * and reported that to meet the AEC criteria tha flowrate should be 1.4 Ipm. Tomb and Raymond** used a taat aerosol of polydispene cost duet end analyzed up and downstream samples for particle she distribution with the Coriter Counter. They report thet the penetra tion curve obtained at 2.0 liters moat closely spprori- mated the AEC criteria. Ettinger and Royer** toed monodisperte aerosol of a 4:1 methylene blue:urtnini mixture. They found that the collection characteristics matched the AEC criteria at 1.7 lpm. They also showed thit the application of shape Actor collection to the Tomb and Raymond data** rrade that tote conshteia with their own. Knight and Uchti* * compared the penetration of a variety of test aerosols through aiutri- 145 ucc 035044 ? RECEIVED NOV 28 1977 R. N. WHttLtR, JR. vf -i ** AS UOC 035045 THE AUTHOR Adrian L. Lindt has recently retired from E.I. do Pont de Nemours and Company as laboratory supervisor for the industrial hygiene and clinical laboratories of the medical division at Chambers Works in Deepwater, New Jersey. Mr. Linch holds a bachelor's degree in chemical engineering (1933) and a master's degree in biochemistry (1934) from the University of Denver. During his 39-year career with du Pont, Mr. Linch conducted research and development in such areas es the manufacture of dyes, dye intermediates, rubber chemicals, organic mercurials, tetraethyl lead, fluorocarbons, stabilization of aromatic amines, and the design of laboratory glassware. In addition to the medical laboratories, his career has included wpervision of a Manhattan project laboratory for a plant producing fluorocarbons and uranium derivatives. In 1953 be entered full-time practice in industrial hygiene. Biological monitoring procedures for the control of exposure to the cyanogenic aromatic nitro and amino compounds were developed under his supervision; personnel monitoring programs for alkyl lead and mercury derivatives, asbestos, radiation, silica-bearing dusts, and carbon monoxide also were established. Additional specialties involved development of air sampling and analysis techniques, design of personnel monitoring equipment, and protective clothing. Mr. Linch is a member of the American Chemical Society, the American Industrial Hygiene Sodety, and the American Academy of Industrial Hygiene, and is a Fellow of the American Association for the Advancement of Science and the Franklin Institute. Ms. Lincb's bibliography includes over 70 publications. In addition to Evaluation ofAmbient Air Quality by fmaonnef Monitoring, he has also written Biological Monitoring for Mnstrbl Chemical Exposure Control for CRC Press. ucc 035046 1 OCCUPATIONAL SAFETY AND HEALTH GENERAL INDUSTRY STANDARDS UNITED STATES DEPARTMENT OF LABOR fL W. J. Uwcy. Jr., tenuiy Occupational Safety and Health Administration \ ucc 035047 General Industry OSHA Safety and Health Standards (29 CFR1910) U.S. Department of Labor Occupational Safety and Health Administration OSHA 2206 (Revised January 1976) RECEIVED DEC 2 1977 R. N. WHEELER. jr ! J ucc Q35048