Document o1ndLz599k7Vn85g2a00mL68

Am Ind Hyg AssocJ 43(8)605-621 (19821 The history of development and validation testing of passive dosimeters is reviewed. Theoretical considerations including possible limiting factors or interferences, are presented. Laboratory and field validation tests are critically reviewed and results are presented for comparative purposes. Evaluation of available data indicates thai passive dosimetry, with some exceptions, is an acceptable method for monitoring gasses and vapors Most importantly, passive systems appear to be as reliable as the now accepted active sampling systems Passive dosimetry -- state of the art review VERNON E ROSE and JIMMY L PERKINS School of Public Health. University of Alabama in Birmingham, Birmingham, AL 35294 introduction Recognition. evaluation and control arc the cornerstones of the application of that mixture ol science and art known as industrial hygiene These three tasks, however, are no longer the eminent domain ol the industrial hygienist In the past decade, a proliferation of training in the recognition of workplace hazards has been made widely available to workers and management alike. At the other end of the spccti um has been the naming of indiv iduals highly specia i ized in the control of specific fwaids. especially thus, involving noise and toxic air contaminants These develop menfs are w el corned because they contribute sign iftca nt l\ i. the ultimate goal ol ptoteenng the health of workers h pros idinp safer and more healthlul workplaces At the same time, professional industrial hygienists re. ogm/c that often the critical step in the process is not recog muon of toxicity , but evaluation of ha7ard which leads m the subsequent development of the most effective means ol control where warranted. This key step of evaluation is the unique domain of the industrial hygienist, often supple mented by other members of the occupational health and safety team. Where evaluation requires the determination of worker exposure to airborne toxic substances, the industrial hy gienist has seen a rev olution in the development of sophis ticated techniques and equipment. The "organ-grinder" impinger sampler is a relic, having been replaced by constant flow. eight-hour battery-operated pumps, light enough to be carried by the worker. The liquid bubbler and impinger have been replaced bv the charcoal and chemical substrate sampling tube. The laboratory has come to the field in the form of the portable gas chromato graph and infrared monitor, albeit with a price rise directly proportional to the sophistication of the equipment. Even the once lowly, direct-reading detector tube has become legitimate with the establishment of government programs to certify accuracy and precision. But while most evaluation techniques were reaching the point where the industrial hygiene staff required the addition of someone with a Ph.D. in electrical engineering, a new dev icc has appeared which has the key of simplicity -- the personal passiv c dosimeter personal because n can K woi by the worker in close proximity to the breathing zotn pasxive. because there is no pump to move the an ovei a collector, which equates to fewer calibration and m.unii nance problems Some quarrel with the term dosimeter. with purists preferring to call them collectors, monitors, oi samplers While many of the devices arc collectors and require the application of subsequent analytical procedures Others provide for a more direct measurement ol "exposure dose." Their basic appeal, however, is simplicitv ol use Theoretically. elaborate calibration procedures are unneves sary. and all that is needed is a lairly reliable timepiece to measure exposure duration. There is some recognition thai temperature and humidity may affect the observations therefore, most manufacturers adv >sc the user to report these env ironmental conditions to the analytical laboratorv pro cessing the dosimeter. Ratherthanvicwingpassivedosimctersasanothervvav to replace the industrial hygienist, industrial hygienists must recognize and appreciate the potential of the dosimeters in helping to achieve the hygienists' goals That potential isignificant in that personal dosimeters, if properly toed oflcr Ihc opportunity to revolutionize the evaluation step The parallels with detector tubes, as well as w ith noise and ionmng radiation dosimeters, are obvious Indeed, the parallel with radiation dosimeters, especially film badges is striking. The opportunity to significantly expand the mea surement of worker exposure to many toxic materials can provide a quantum leap in our ability to provide sale and healthful workplaces. With any sampling dev ice. however there also must be the understanding that vise ol such dev ices is only one part of the evaluation step. The eoneepis ol proper selection of workers at risk, the understanding ol limitations, interferences and similar factors, and uli imaicly the proper interpretation of the results arc 'till key ingicdients in the evaluation step. 1 he possibility ol "lalse nega tive" decisions leading to erroneous assumptions ol saletv. or "false positive" conclusions leading It' unwarranted expenditures of resources (or eorniols still exists regardless of the measurement device used Copytgm 1987 Af*r*n Industrial Hv^iprv Atwri4iK>< Am*nc*n Industrial Hypfnp Association JOURNAL (43) f 8? 3M 101537 60 - With the rapid proliferation of passive dosimeters in the past several years, it is appropriate that industrial hygienists evaluate the "statc-of-the-a riband. as professionals, become involved with the proper application of these monitor ing dev ices. theories of operation In that passive dosimeters bv definition do not use an air mo\ ing dev ice to transport contaminated air to a collector, nai ma I I orces are relied upon to ensure that a representative amour- o! i oniaminant is "seen" bv the detector. 1 o date, on: ( 1 ' w i principles has been applied in the design of do'irr tin "I he first, and most widelv uved. iv the principle of ni contaminant molecule-, through a stagnant pas i ,i: > i .j v t f 1 he second principle inv olves ihc absorption in am* -i.h-cuucnt ftrrmraiinn ol contaminant molecules throl p* .j mi mbrane, monitors relv on the movement ot eonlannnarr n .'iiinUs across a concentration gradient which for stead.-s;.,u i ond it ions, can be defined hv Kicks Kirst law ol I )i! I u-ion \\ = - I)A d.s (1) where V- = mass translei rate, ng sec. [) = dillusmn coefficient. cm' sec, A = cross sectional area of diffusion path. cm~, and dc ds ~ ihe instantaneous rate ol change in concentra tion over diffusion path, (ng cm'Vm 1 Considering the change in concentration (Ci -- Cn) over the total ditlusion path length (Xi -- X,, = --1 ). equation ( I ) becomes u = D J <(', - c,,) (2) where I = length ol the dillusion (static) path. cm. Ci = ambient concentration of contaminant, ng cm1, and Ci, = concentration ol contaminant at collecting sur face. ng cm'1 II an effective collection medium is employed, the contam inant concentration at the surface of I he collector (Cn) can be assumed to be zero, and multiplying both sides of equation (2) bv time, yields: A M = r> -- (Cl) t (3) where: M = total mass transferred, ng. and t = time that the badge is exposed to the contami nated air. sec. It is also interesting to note that the units of the product of Hand A.divided bv l..arccni* see, which are the same units associated w ith active air-mov ing dev ices such as personal sampling pumps. Rearranging equation (3) as follows C, Ml DAt (*l it becomes apparent that live lactors alfcct the measurement of ihcamhicnt air concentration ol a suhstanccfC ,1 1 wool the lactors (l and A) arc physical parameters associated with the construction of the dosimeter, one ( M ) is prov ided bv measuring the total mass of contaminant collected hv ihi sampler, another is the duration (t) the sampler was evposed it' the contaminated atmosphere, and the linal lactor (l)i i- an individual propertv of each vapor or gas It also i- known"' that the diffusion coefficient is direct I \ propin tuinaI to the absolute temperature (T ) ol the vapor, raised to three-halves power and inversely proportional to the aim., sph eric pressure (P). ,, 1Do --`` (51 Dosimeters that relv on the principle of fH'riinaiit'n through a membrane are especially useful w here the contam inant of concern is usually found mixed with other interleiing vapors or gases or when a liquid collecting medium is employed. The goal then becomes to identify a membrane material that is highly permeable to the contaminant ot interest and impermeable to most other components in the atmosphere, and or the collecting media The determination of ambient concentrations of a con taminant using a permeation dev ice can he determined from the lormula: C = wk i (6) where C = concentration of contaminant, ppm. w = nusv ol contaminant collected, gig. k = permeation constant, ppm-hours ^g. and t = exposure time, hours The permeation constant (k) is determined experimentally and is a function of the specific membrane material and contaminant ol interest sources of measurement error The most obvious sources of error for both types of passive dosimeters arc apparent from equations (4) and (6) Com mon to both badges are determinations of the mass of con taminant collected and the time of exposure of the dosimeter to the contaminated atmosphere. For the diffusional moni tor, accurate knowledge of the physical parameters asso ciated with badge construction (length and cross-sectional area) and the diffusion coefficient of the contaminant are important. There are at least nine prediction methods for calculating the diffusion coefficient, and in one studs com paring observed and expected values for more than 100 compounds it was not uncommon to have less than 50 percent of the calculated results within 5 percent of the observed.' Montalv o has described a procedure for limiting errors associated with computed diffusion coefficients."* At 3K 101538 Am Ind H)f Assoc U43) Avfux ISf." least one manufacturer, the 3M Company, makes available its procedures for determining sampling rates (DA L)for its badges.1'1 Its approach has been to experimentally determine the sampling rate for fixe or six compounds in a chemical Ijmih 10 establish the relationship between the diflusion coellicicni and the measured samplinp rates Samplinp rates lor *>ther compounds are determined Irom the diffusion cm 11 iL iems calculated h\ the Hirschfelder equation and the en.p r ic jl relationships developed from the lest compounds "I hi r a i n in a le for t he select ion of the Hirschleldcr equation is n. i i ri hut in the study of the nine diffusion coefficient ii .i' ihe author concluded that for hipher molecular v i ompounds the Huschteldei. Hiard and Spat/equa- i'ii i in closest apreemeni with determined values.13 I " p. i mcatinn monitor, accurate determination o! the ; ; . r coefficient lor each monitor is necessary lor i , i l accurate results factors inllueneinp permeation 0 . la.: i h ic kness and umfoi mity ol the membrane, at finny ' ' ' 'Mi iv hiane lor the analv le. sw el line oi shnnkape of the 1 i ' . in and possible elchmp bv corrosive chemicals I 1 p 'Slims associated with accurate determinations ol r i .. ' ol ihe contaminant collected arc similat to those ii .id uiilt other collection devices such as charcoal or so.i.i pi I lubes, or to those in which the collection of the II >iu a nuna m inv olves a chemical reaction with the collection medium Iking known amounts or concentrations of conlammanis 10 deiermmc collection and or desorption ellii it ncics is as ci it tea I a step lor passiv e dosimeters as it is lor oihei methods ol collection Saturation of ihe sorhent as well as Ihe subsequent accuracy ol analy tical techniques are also pa11 ol l he IoiaI ei i ot associaicd w ith the measurement Another common concern in all types of environmental measurements is the potential lor interlcrcnces. either posi tive or nepative, Irom other contaminants in the sampled air As ihe evaluation ol passive dosimeters has matured, increased attention is hemp paid to possible interferences in mulli-conianunani exposure situations, in both the labora tory and field. In evaluatinp such interlcrcnces it should be recopm/cd that there are several potential sites for such interferences to appear, eg., effects on adsorption or ahsoipnon efficiency ot the samplinp medium, chemical tcjctmns ol tw o or more contaminanis prior to analysis, and the multitude of interferences associated with analvsis of complex mixtures of pases and or vapors. These problems also are found in the more classical samplinp and analyti cal methods. Accurate measurement ol the time the samplinp device is exposed, is essential to most industrial hygiene samplinp procedures. For both short-term and full-shift exposure measurements, errors less than one percent, i.e 9 seconds in 15 minutes and 4.8 minutes over 8 hours, arc not unreason able poals. For the diflusion coefficient and possibly the permeation constant, it would appear that three factors have thepreatest eflect on variability. These tactors are the two already identilied. temperature and pressure, and. less readily apparent, the velocity of the air external to the badpes. Affifnear Inoustfta Hyptenp Awrisbon JOU^NAl Ii3) e BP Considering temperature and pressure, and rclcrrinp to equation(S) it can be shown that a temperature rise Irom 5 to 35 C would give a lb percent increase in the diffusion coefficient, while a rise in harometnt pressure Irom "MU to 8 10 mm Hp would cause a 14 percent decrease 1 Howevei. at the same time, the changes in temperature and pressure also arc affecting the concentration (mass volume, actuallv density is the proper term bui most authors use concentra tion) of the contaminant in that concentration is inveisciv proporiional to the temperat ure and directly proportional to the pressure. As a result, the total mass ( M ) collected hi ilu dosimeter is onlv shghtlv aliened hv lempciaiurc (Mol i and is independent ol the pressure ' C onscqucnili w Ink ai ambient temperat ures. the d ifl usion coell m cm will iik i c jh a bout 0 5 percent per C`. a nd t he tola I mass collet icd hi i hi sampler will increase less t ha n 0 2 percent pci - ( 1 hci cl oi i a temperature change Irom 25 to 30 C. il uncoi reeled will introduce a measurement error of less than one percent while a change from 5 to 35 C. i! uncorrecied would introduce an error o( about live percent '1 he final source o( erroi to eon side i is i he v clot n \ ol ilu air external to the dosimeter, often this is rclcrrcd to as lace velocity. In an early assessment ol lace v clocity cl I eels, especiallv the lack thcrcol. 1 ompkins and Goldsmith point out that the important consideration is to contain all resistance to contaminant transport w ithin the stagnant air lay cr inside the device1" As Jonas el al subsequently noted, the lace velocil v direct I v a fleets the concent rat ion gradient ( : -- C in equation (2). and C'i can no longer be assumed to he ihe ambient concentration w hen the air external to the budge is stagnant ,6` With zero or low face v cloeuies. ihe lengt Ii (I I ol the diffusion palhwav is ellcclively extended, and theie is a decrease in the measured amhieni concentration In Tompkins' and Goldsmith'x work w ith the CASH\ I)G F'". they determined experimentally that as long as lace veloci ties were greater than 7.5 cm sec (15 fpm) there was "no significant eflect on dosimeter response." however, expen mental results supporting this conclusion were not pre sented 111 FI igh face v c loci tics ma v also affect the concent la lion gradient Commercially available diflusion devices relv oncithcra large ratio ol di ft usion path lengi h i" dil I usion tube diameter or a wind screen to limn crtoi' iiom this condition. One of the most comprehendv c tests to document sources of error has been conducted under contract lor the National Institute for Occupational Safety and Health, and although concluded, it is not yet available as a public report The study involved evaluation of the GASBADGI and 3N1 Organic Vapor MonitorTM (the DuPont budge not heme available at the time the study was initiated I via challenge with several organic vapors The factors investigated were precision, effects of storage, maximum and minimum levels of quantification, face velocity cllect'. el I eels ol temperat ure and humidity, off-gassing (related to sioiagel. exposure to mixtures, problems associated wuh applicable analytical methods, and adsorption ol the coniuminunt by the badge itself with subsequent leaching in the sensing surface The possibility of adsorption hy the badge body, thus giving f 3H 101539 higher results, if the contaminant is subsequently released to the acme medium, is of special concern in using passive dosimeters to measure very low ambient concentrations such as might be found in air pollution studies. Such interest and concern arc evidenced h> research on the subject being sponsored by the U.S. Fn\ironmental Protection Agency F PA) Because of the lower concentrations involved w ith air pollution studies as opposed to workplace environments, ihe EPA also is concerned with the background or postmanufacture contamination levels associated with the sens ing medium Initially. the focus concerns organics and actikaied charcoal In summarv. although numerous factors may affect the i inal calculation ol concentration. only face velocity and the determination ol the dillusion coefficient are unique sources of error lor passive collectors. Therefore, if face velocities are sufficient to prevent "starvauon"(probably greater than 7 f cm sec I and if diffusion coefficients have been accurately calculated or experimentally determined, passive dosimeters 'limiId go e results comparable to those obtained w ith tradimnal acme sampling systems, statistical considerations In evaluating any new monitoring method, extensive lahoraory and field testing is necessary. Interpretation of the epulis of these tests requires the application of appropriate statistical techniques. The use of statistical techniques which ire meaningful and easily understood is important: conse quently, a discussion of the techniques used to evaluate passive dosimeters is appropriate. There are numerous statistical tests w bich can be applied o both field and laboratory validation data. The main difcrencc between the two situations is the degree of certainty of the "true" concentration of the monitored env ironment. in the field the true value is usually an estimate based on the csults of a standard sampling and analytical method In the ahoratory. experimental "known" concent rat ions are evolved and arc then used for comparison with the concentrations estimated from sampling and analytical methods. What is often not stated is that a certain amount of error also exists m the determination of laboratory-evolved "know n" concentrations. These errors are often difficult to estimate The "known" concentration is often calculated bv weighing a sy ringe before and after an injection period (mass valance) or simply by injecting or allowing to diffuse a -neasured volume. It is assumed that the aliquot delivered vas vaporised ordiffused intoa testchambcrofknounsi?e. Possible sources of error include adsorption to or leaks from .he test chamber, absorption and adsorption to articles placed in the chamber, degradation of the analyte by air oxidation or hydrolysis at high relative humidities, and error in measuring the injected contaminant. A backup monitor ing system may be used to ensure close proximity to the 'know r," concent tat ton, For example, an infta-red (l R) ans wer or gax chromatograph may be used as a check on a k now n" concentration. In other instances an IR analyver or a direct reading instrument may he the only method for determining "know n" .ot concentrations. In this case the error in the instrument can be calculated or estimated. Charcoal tubes and critical ori fices also have been used to measure "known" concentra tions. If error in both the "known" concentration and the estimated concentration are considered, statistical tests used to validate the experimental method become considerably more complicated; hence, the error in measuring the "known* concentration is usually assumed to be small and unimpor tant.^ Meihodsdescribed above for determinml the "know n' concentration vary in their accuracy, a fact which should be considered when evaluating validation data for any sam pling and analytical method When one is validating a method in the laboraiorv. there arc tw o main considerations' the variation of the samples or data points about their mean, and the dev iation of the sam ple mean from the true mean or"known"concentration The first consideration often is called precision and is probable the most important and reliable measure as it docs not depend on the error in determining the "known"conccniration Precision is estimated by determining the coefficient ol variation (CY) or relative standard deviation of the data set as follows- CY - X 100 17) where: s = Standard deviation of sample data set. and X = Mean of sample data set Where samples arc taken at several concentrations, it is necessary to determine a pooled coefficient of variation which involves determination of number of levels tested,""' It should be noted that determining the number of concen trations (or more appropriately, the number of statistical levels) is not always straightforward. For example, if 10 samples arc taken at each of three concentrations, and if within each concentration five of the samples are collected over four hours while the other five are collected over eight hours, arc there three levels or six levels? The important point to consider is whether the differentiation of a level is based upon an anticipated difference in the sample mean. Certainly if the investigator designs the experiment with different time levels, there is an anticipated effect of time on the mean. Unfortunately. when experiments arc so designed, statistical analyses at the various levels usually are not performed. The second statistical consideration, the difference between the sample mean and the "known "value, is sometimes called accuracy, but the term bias is more appropriate. It is defined as: X - Xf. b = --------X 100 Xo (8) where: X = mean of sample data set. and Xo = "known" value at level tested If more than one level is sampled, it is necessary to determine the pooled bias of the data set."" 3M 101540 Am Ind Hyp Assoc J (43 AuCuSt 19B: The bias for a given set of data can sometimes be cor rected. If the average bias (either the average of several samples at one level or the pooled bias for several levels) is large, one should note if the components of the bias value (either the indn idual samples or the levels) are consistently negative or positive. If the bias is large and varies consis tently m one direction, the precision nevertheless mat be quite small. In this case a physical or chemical variable may be consistently affecting the method (a systematic as opposed to random error), causing the experimental values to con stantly fall short or long of the "known"concentration. This form of bias should be corrected. In addition to these statistical tests, others have been used to assess the validity of passive monitoring systems. Overall sy stem accuraev"" has been defined as (2 X CV) 4 absolute bias, expressed as a percent. Others'121 have used the percent age of the "known" concentration accounted for by the sample mean i two standard deviations as well as the term systematic error11'1141 which is equivalent to overall system accuracy Relative standard deviation has also been used, and is defined as the equivalent of CV."S| Additionally. some authors report only raw data while others report means without standard deviations or sample sizes, and various other combinations While all of these statistical determina tions have utility, it seems important for comparative pur poses to consistently use those determinations which give the most information in the simplest form. Certainly, bias and precision meet these criteria. Discussion ol one other point seems necessary NIOSH"0' has proposed as a guideline for their own internal purposes that sampling and analytical methods meet a minimum requirement of 25 percent accuracy ; that is. the absolute totalerrorofthemethodshouldbclessthan25 percent in at least 95 percent of the sample population (assuming a nor mal distribution) NIOSH derives the maximum precision value for an unbiased method given the accuracy criteria stated. This value (12.8 percent) is the maximum precision value acceptable for an unbiased method. Although the 25 percent accuracy criterion has been criticized by some authors.116' it was adopted for NIOSH's ow n internal use and is not meant as public policy. However. OSH A adopted the same criterion for the benzene standard, w ithout a complete derivation or explanation. Consequently, this criterion has been criticized and alternatives have been proposed.,1,) A second important point is that bias is also considered in the 25 percent criterion according to a somewhat complex statistical relationship."01 but the overall svslcm accuracy as defined earlier"" is a fair approximation if the method has a true bias, i,e,, its mean is statistically different from the "known concentration." A final point is that as the number of samples at a level increases, the standard deviation and CV should decrease. These considerations are important w hen evaluating passive monitor validation data, especially in those cases where manufacturers have stated that they have met the 25 percent accuracy criterion. For field comparisons of conventional and passive moni tors. different statistical tests are necessary. If passive moni tor values, for example, are plotted against charcoal tube results (Y vs. X) and more than one concentration is sampled, one would expect an increase in X to cause an increase in Y. If the increase is linear, and the sample values lie on the regression line, the correlation coefficient (r) would have a value of one. If a change in X brings about an equal change in Y. then the slope would aUo have a value of one If the individual values for the two dev ices are indeed equiva lent. the line should intercept the origin Each of these rela tionships is expected within reason The difference of the slop from one. the correlation coefficient from one. and the intercept from zero can and should be tested. In order to perform the regression analysis described above we must assume that X (active sampling data) is noi subiect to error. Of course, vv c know and can calculate undei laboratory conditions the error ol active sampling systems There are at least three reasons why this error is oticn overlooked. First, it is assumed that consideration ol the error in X would only cause small diflerences in regression analysis results. Second, in addition to laboratory demon strated error, a range of errors introduced by varying envi ronmental conditions must be considered While difficult to assess, these errors may have a profound effect on X. and indeed the error in the X measurement may be as great or greater than that for Y. Finally, if the erroi in X is to be considered the statistical tests are complex. Such tests have been discussed for biological problems."6' however, the the ories apparently have not been applied to sampling and analytical methods even though their appropriateness has been recognized." applications From a historical vantage, one of the earliest reports of a "passive" monitor for evaluation of airborne contaminants was patented by Gordon and Lowe in 1927 <J0, Their gas detector for carbon monoxide inv olv ed an "easily frangible vessel containing a solution of salts including palladium chloride, and a covering for said vessel of a light colored absorbent material." The principle involved breaking the vessel (a small ampule) and noting the subsequent color change of the solution as it reacted with the carbon monox ide on the light colored absorbent material This type ol semiquantitative device was certainly a forerunner ol those that are available today. though it was undoubtedly affected by air velocity as a stagnant air layer was not employed An extension of Gordon and Lowe's concepts in the late I9b0`s provided the basis for Plantz cl al to develop a personal dosimeter for measuring hydrazine, unsy mmctrical dimethylhydrazine and monomethylhydrazine.1211 The reac tion of these compounds with a "colorimetric substance" (bindone) produced a purple color, the inicnxiiv of which was dependent on both concentration and duration of expo sure. Color standards then were used to estimate t he concen tration as a function of the time the badge was exposed to the contaminated air. consequently. the method was only semi quantitative. In considering sources of error the authors noted that the purple color would also be produced by all volatile bases that were tested, including ammonia, aliphatic amines, aniline and cigarette smoke Amwican Indiana' Hypiene Associilton JOURNAl (43) 8'8? 3M 101541 609 Of interest in this review, however, art quantitative devices based on the principle of either gas or vapor diffu sion or permeation through a stagnant air layer. The first such device to be reported in the literature was described by Palmes and Gunnison in 197? 1221 Theirdcv ice employed ihe principle of gas diffusion to determine airborne concentra tions of sulfur dioxide and w ill receive further consideration subsequently Togam the best overview of the variousapplicauons of these concepts, it is probably best to proceed bv considering first the inorganic and then organic gases and \apors inorganic gases and vapors ammonia In 197b. Ma/ur ri aI described the use of the Abcor GASBADGF to sample employee exposure to ammonia (this device current 1\ is not marketed) '*1'The investigators replai ed the charcoal pad normalh found in the G ASBADGE with an acid impregnated absorption pad. Of three acid", tested. phosphoric w as most successful in pros iding the best approximation of theoretical concentrations. They deter mined, how ev ei. that v ola tile amines, specifically cvclohcxvIamine could produce high readings, as high as 185 percent ol the synthetic atmosphere. This led them to replace the glass fiber draft shield on the front of the GASB ADGE with a "charcoal impregnated glass fiber filter which had been pretreated with alcoholic KOH containing 0 I percent surlaciant." 1 he charcoal served to adsorb amines as thev dif fused into the dosimeter, while the KOH (aided hv the wetting agent) eliminated irreversible ammonia adsorption hv the charcoal, which would have caused underestimation of the ambient concentration. Additional laboratory exper iments demonstrated that storage time of up to 47 days, pi lor to analysis, did not appear to adversely affect the results More recently. DuPont has developed a commercially available svstem lor the measurement ol several airborne contaminants including ammonia. In 1981, Knng ct al, described DuPont's PRO-7 EKT" sy stem for ammonia, nitro gen dioxide and sulfur dioxide sampling anal? sis using a col orimetric readout instrument.,~4' 7 he ammonia badge relies on moleculai diffusion of ammonia and subsequent chemical reaction w ith a solution of 0,?N boric acid and 0.03N sodium potassium tartaratc (.we) After exposure, the reagent pack is removed from the badge holder and analysts is initiated by pressing reagent "blisters" w hich arc adjacent to the absorb ing solution This action causes the release of a modified Nessier's reagent and the subsequent development of a colored solution. Eorammoma. maximumcolor intensity is developed at 425 nanometets. The absorbance of the sample is then compared against a standard curve based on Beer's l aw After determination ol the precision of the analytical method and verification of the linear range of the co)ot chemistry. laboratory testing was conduct, .1 to establish the operational range as well .is precision and accuracy of the oveiall method (see Table I) The minumum and maximum limns ol the sampling range were found to be 50 and 500 ppni-hours. respectively For an eight-hour time weighted avetage, these values cot respond to oi.e-lourth and two and 610 one-half times the current ACGIH Threshold Limit Value of 25 parts per million.12*1 In considering sources of error, environmental effects including temperature (10 to 40 "Cl. relative humidity (10 toRO percent), pressute(730 to 790 mm Hg). and face velocity (2.5 to 125 cm sec) were included Of the environmental factors evaluated, temperature and the concentration of the contaminant were identified as being responsible lor 98 percent of the data variation. For ammo nia, a temperature correction factor ofO 6 percent per degree centigrade was suggested. Also invesneateO was the storage stability of both unexposed and exposed badges Results indicated that refrigerated slot age is ncccssarv to extend i he shell life of unexposed badge' Once the badge isevposed to ammonia and before the reagents ate mixed ihe badges ean be stored lor one (room temperature) to three (relrigerated I weeks without losing any absorbed contaminant Once the reagents aie mixed and color Iormation is st.iru d i he badge should he read w ithm 90 minutes. Ad dm final te-i i rig te - till s conducted by DuPont are shown in Table I carbon monoxide Shor and Anders, of the 3M Compunv. have described the 3M "direct-read diftusional monitor" lor evaluation ot exposures to carbon monoxide.1 The principle involves the reaction of the carbon monoxide and an unreporied reagent(s) to give a visible color change from pink to tan 7 heoretically. "il any pink color is observ able at the end of the exposure period, then the exposure was less than the one time-weighted-average of 400 ppm-hours " They also state that noting the time to the endpoint allows lor calculation of the average concentration of carbon monoxide during the exposure period The authors present summary results of laboratory evaluations using an infrated radiation dev ice to establish "know n" concentrations (see Table I). chlorine Hardy ei a! have described a personal chlorine monitor (REAL. Inc ) which employs the principle of permeation of the gaseous contaminant through a silicone membrane and into 10 mL of a fluorescein-bromide solution.1'1'1 Colorimet ric techniques then can be applied to determine the chlorine concentration. The authors report a detection limit of 0 013 ppm chlorine for an eight-hour exposure, with a "working range" of 0.1 to 2.0 ppm. They also suggest that for shorter time periods, concentrations of up to five ppm can be deter mined. Other observations included effects of temperature, humidity, absorbent concentration. pH and response time, with all laboratory results presented graphically. Moleculon Research Corporation has recently introduced a chlorine monitoring device which relies on plastic film impregnated with liquid reagents.<2,`' Exposure of the badge to chlorine gas gives a visible, "blue-purple." color change. Optical transmission measurements, and comparison w ith a standard curve, can then provide quantitative exposures in ppm-hours The manufacturer's summary results indicating effects of temperature, humidity, wind velocity and concen tration are reported as presenting an error at the 95 percent confidence level, which is "less than 15 percent." 3M 101542 Arr Hyf AiSoC J M3' Aufu'.l 196? Chemical TABLE i In rganic Gases and Vapors Laborat ry Results Dosimeter* Bia." Precision' Range" (ppm) Reference Notes Ammonia Nitrogen Dioxide Sulfur Dioxide Hydrogen Sulfide Mercury CO DP DP GB GB DP DP MDA GB DP DP GB 3M 3M 3M 05 05 -3.2 -3 2 -0.9 -4 9 -1 -0 8 05 17 03 74 69 93 21 7 75 87 41 13 8 58 76 15 3 9 2 47 20-50 20-48 6-62 4-11 4-11 4-11 6-9 4 6-5 3 4-11 4-11 1 622 0 03^0 3mg/m' 0 05-0 2 mg/m 50-1830 24 26 23 1 3B 24 36 38 24 1 32 33 27 TC H1 (. HI (, 'DP-DuPont Pro-Tek Colorimetric System Badges. 3M=3M Company Monitor. MDA=MDA Scientific. GB=Abeor GASBADGE "See text, equation (8| 1 See text, equation (7) "Some values are rounded to nearest whole number "Bias consistently negative "Results derived from Table III of McCammon et at "Results calculated from data provided in reference "This product IS not currently marketed 'Bias could not be calculated from data given hydrogen sulfide In 1977. Tompkins and Goldsmith described the developmcnt of the GASBADGE personal sampler.'" Although later work with this device focused on the collection of organics on an activated charcoal substrate, initial studies researched sampling of both organic and inorganic com pounds. (The GASBADGE for organic vapors is now mar keted by National Mine Safety Company, and those for inorganic vapors are not currently marketed.) Applications involving inorganic gases relied on collective elements of an "appropriate substrate impregnated with a chemical medium specific for the contaminant of interest." Based on 60 obser vations. the authors' statistical summary is presented in Table I. Eighty percent of the measurements were within 25 percent of the "true" value. Challenge concentrations were established in a "well-mixed" environmental test chamber and were measured with an "independent wetchemistrv sampling train." Hardy and associates have described a permeation device (REAL. Inc.) which relies on the permeation of H*S through a dimethyl silicone membrane and subsequent reaction w ith a solution of 0.2N sodium hydroxide and EDTA.'30' The colored product (methylene blue) is measured spectrophotometrically and compared with a calibration curve to determine ppm-hours. A knowledge of exposure time then allows for the determination of average exposure over the measurement period. T he authors note that a critical step in Amfiicin Induslnjl Hygiene Association JOURNAL MJJ * B? the development of such a dev ice is the experimental deter mination of the permeation constant (see Equation 6). w hich inv olves calibration of each monitor by exposure to know n concentrations of the contaminant. The results of this labo ratory research demonstrated a detection limit of 0 01 ppm for an eight-hour exposure, w ith a working range ol 0.1 to 20 ppm and a linear response up to 200 ppm. The working range corresponds to one one-hundredth to two time' the current eight-hour TLV of 10 ppm.'2i'1 Evaluation' ol env ironmental effects indicated that neither temperature, over the range of--3 to 39 C. nor humidity. from 0 to 99 percent relative, caused any significant variations in response of the device. Further research demonstrated a good response to high concentrations in less than one minute, adequate sam ple stability up to 10 day s if EDTA is used in the absorbing solution, and negative and positive interferences, respec tively. from chlorine gas and nitrogen dioxide Precision and bias were not reported. Anotherapproach forthedetermination of gaseous hydro gen sulfide has been reported by Gracdel and Franey.1311 Their research involved using a semiquantitauve method without a stagnant air laver and rely ing on t he discoloration of lead-stabilized polyvinyl chloride (PVC) The technique involves the diffusion of gas in a polymer and. at high H:>S levels, the detection rather than the measurement of toxic levels of HsS. Screening application' for low lev cl exposures also are discussed. 3M 101543 11 mercury In 1977. McCammonand Woodfin orNIOSH reported the results of a laboratory evaluation of 3M`s mercury vapor monitor.'32' The monitor's operating principle ins olves molecular diffusion and deposition of mercury vapor on a gold substrate. The resulting ch.-.nge in electrical conductivity across the gold loil is related to the amount of mercury absorbed by the foil Three other sampling methods, all of u hich in\ ohed the active movement of air, also were in\estigatcd and include the l.ASL tandum sampling tube, the hopcalitc tube, and the iodine impregnated charcoal tube, l the passive monitor, precision and accuracy, the effects o) lace velocity and temperature.and potential interferences were investigated Concentrations of mercury vapor in an exposure ehamhet were monitored with an ultras iolet mercur\ \ apor meter, w hich in turn was calibrated by measuremenu using the L ASl. method. To determine precision of t he monitors. 12 dev ices w ere exposed to a test atmosphere Rcsulis from three measurements of the test atmosphere mine the LA.SL method gave an "expected"concentration ol 0 05b milligrams of mercury per cubic meter of air (mg ro3) with a standard deviation (SD) of 0.002 mg m3 and a coefficient of variation (CV) of 0.037. Precision and hiav calculated for the data given in Table 111 of McCammon ei a/.13' is summarized in Table I. A leasi squares regression analy si', of ihc combined precision and accuracy results for the passive dosimeters versus the "known" concentrations gave a Y intercept of --0.004 mg m5 and a slope of 1.003. Tcsts for the effects of face velocities from 25 to 125 cm sec (50 in 250 Ipm) did not appear io have any adverse effect on performance, while variation of temperature experimentally confirmed us effect on hoth the diffusion constant and the concentration of the contaminant. The potential effects of changes in relative humidity were not discussed by the authors. The other area of investigation in this study involved potential interferences of chlorine, sulfur dioxide, and hydrogen sulfide. Concomitant and sequential exposure to mercury and chlorine, the latter at high levels (5.8 ppm), produced a negative bias, but a similar effect was observed with the llV meter and the l.ASL system. The authors suggested that the mercury and chlorine may have been reacting to form mercuric chloride which was not being measured by any of the systems. The interference effects of sulfur dioxide and hydrogen sulfide, although less than chlo rine. also were confirmed. In 1980, McCammon and his NIOSH and OSHA coworkers conducted further tests of the four previously described mercurv vaporsamplingand analytical methods '33' The design of this laboratory experiment involved inter comparison of four methods, and the findings suggested that the variability of the iodine charcoal tube method is signifi cantly different from that of the other three methods. It was observed that the other three methods, including the 3M passiv c dosimeter, exhibited cood precision over the concen tration range of 0.05 to 0.2 mg m3 as shown in Table I. Recently SKC. Inc., introduced a gas monitoring badge (produced by G M D. Inc.) which uses the principle of molec ular difiusmn (without a stagnant air layer) to collect mer it cury vapor.1341 The sampling media is referred to as"Hvdrar Sorbent."and "extensive" but unpublished field and labora tory testing are cited to show that "chlorine, moisture, etc., do not interfere" with measurements. HYDRAR is devel oped from a "manganese dioxide catalyst materia) similar to `Hopcalite.' " Quantitative determination is made bv chemical desorption of the mercury and analysis with atomic absorption. nitrogen dioxide In 1976. Palmes ei al. reported the result - of their evaluation of a personal sampler for nitrogen dioxide (NO^I1351 This work was an extension of their earlier pioneering efforts in developing a personal sampler, employing the principle of gas diffusion, for sulfur dioxide In their design, the sam pling dev ice was a 1.3 cm (0 5 inches) aery lie tube, 7 1 cm (2 8 inches) long At the "closed"end ol the dill usion pal h I tube) were placed three stainless steel grids coated wnh ineihanolaminc(TEA) TEA wasselected because. I) u captures NO efficiently. 2) it provides a stable sampling surface, and -1 n yields a chemical complex with NO. that is very stable over time. Subsequent analysis yielded a colored complex w hose absorption was measured at 540 nanometers Results were then compared against a standard curve w hich obey ed Beer's Law The experimental evaluation of the NO. sampler involved chamber measurements compared wnh "known" values determined by the volume of NO. introduced to the chamber or the weight loss of NO,> from a permeation lube. Although neiiher indiv idual nor sutnmarv results w ere pre sented. graphical comparison of the data indicated a close agreement between the passive sampler resulis and theoreti cal concentrations. The effects of wind velocity and direction as well as stability over time also were considered. In deter mining wind effects, the uptake of water vapor, rather than NO*, was measured. The results indicated that there was an increase in average uptake with increased velocity and that the 45 degree incident angle gave the highest uptake (135 percent at 258 cm sec) Across all angles of exposure (0 to 180 degrees) the average uptake increased from 2 to 14 percent as the wind velocity increased from 50 to 258 cm sec (100 to 5 16 fpm). Stability studies indicated that the badges could be used for months both after preparation and before exposure as well as after exposure and before analy sis In the previously described studies w ith the G ASBADGE. Tompkins and Goldsmith also monitored for nitrogen diox ide.1" Their summary results for 82 observations showed accuracies and precisions as summarized in Table I. Eighty five percent of the observations were within 25 percent of the "true" value. A commercial model of the Palmes passive sampler has been marketed by MDA Scientific. Inc., and additional laboratory testing demonstrated a linear collection effi ciency for any given dose, i.e.. concentration X time (see Table I).'36' The sampler exhibited a consistently negative bias as compared to concentration determinations using a continuous monitor and the NIOSH wet chemical method. As noted earlier, the DuPont PRO-TEK system mcludesa badge for nitrogen dioxide. Laboratory test results of this dev ice arc show n in Table I.*3,1 3M 101544 Am \t\G Hf Asioc J (43/ Aufusf 19r sulfur dioxide ^vs noted previously, pioneering work in 1973 on the design Pr a sampling device which relics solely on diffusion of gaseous contaminants through a stagnant air layer is attrib uted to Palmes and Gunnison.'22' Their initial studies involved experimental work on different tube lengths. The collecting medium was a complex of mercuric chloride and the final analysis involved colorimetric determination. The studies demonstrated that, except for very short diffusion paths (tube lengths), the diffusion monitor satisfactorily duplicated the results obtained by both wet chemical and conductnmetric measurements. Although this study did not go into the ramifications of environmental effects and inter ferences. it should be recognized as an important step in developing a new industrial hvgicne technology. The last of the three inorganic gases jooked at b\ Tompkins and Goldsmith in their studies of the GAS BADGE was sulfur dioxide."' Summary data for 23 observations on this gas are included in Table 1. One hundred percent of the observations were within 25 percent of the "true" values. The results from DuPont's tests on their sulfur dioxide badge also are shown in Table l/38' organic gases and vapors Most passive dosimeters designed to sample for organic gases and vapors use activated charcoal as the adsorbing medium. As we know from its extensive use in active sys tems. activated charcoal has an affinity for a wide range of organic compounds. Consequently, the discussion on the applications of passive dosimeters for the measurement of organic gases and vapors first will focus on devices usingactivated charcoal and then will turn to specific organics w hich rely on other collecting media. Chemical TABLE II Organic Gases and Vapors Laboratory Results Dosimeter* Bias'1 Precision" Range" (ppm) Reference Notes Carbon Tetrachloride Toluene Formaldehyde Benzene Ethylene Oxide Halothane Enflurane Acrylonitrile Hexane Vinyl Chloride Methyl Chloroform Tnchloroethylene DPA DPA NMS DP DPB NMS NMS 3M 3M 3M NMS NMS R 3M DPA NMS 3M DPA NMS 04 0.3 -1,7 1.5 33 -4 1 1.8 -1.4 3 -2.8 003 -1.2 -0.2 -5 9 -10.6 24 -3.9 -6.9 -0.5 44 5.25 17 63 47 17 17 3.2 74 4.8 87 2 37 47 45 2 7.6 77 1.9 3-18 57 228 12-47 0.2-4,2 3 24 0 8-5 4 13-13.5 300 0 5-20 0.5 20 07-19 10-37 1 5-14 160 840 160-840 15-65 20-200 20-200 15-67 10 E 45 13 FJ 55 46 13 FJ 1 CG J 53 4 44 J 44 J 39 13 fj 2 HJ 48 IJ 48 fcU 12 FJ 46 1J 48 E1J 12 FJ *3M - 3M Company Organic Vapor Monitor, DPA and DPB = DuPont PRO-TEK G-AA and G -BB Organic Vapor Badges. NMS = National Mine Safety GASBADGE. R = Real. Inc MINIMONITOR. DP = DuPont PRO-TEK System Colorimetric Badges "See text, equation (8) rSee text, equation (7) nSome values are rounded to nearest whole number cSmall sample size fKnowns were calculated using charcoal tubes with critical orifices This could affect the bias measure. `'Preliminary results "Permeation dosimeter 'Bias consistently negative ''Results calculated from data provided in reference Ammon indust'ii! Hygwnr Association JOURNAL (43) f8? 3M 101545 (13 activated charcoal devices of March. 1982. there were four manufacturers of passive J.iiimeiers which rely on diffusion and subsequent adsorpt m on to activated charcoal; National Mine Service Comr,,n\ (GASBADGE). 3M Company (Organic Vapor Moni- ri. DuPont Company (PRO-TEK. G-AA and G-RB i h game V apor Air Monitoring Badge), and the Mine Salety pplmnce Company (Vaporgard Badge). In I97T Tompkins and Goldsmith described the lirsi . mmercial passive dosimeter for monitoring organic i pors `1' I he GASBADGE relied on molcculardiffusion ot 1 ; sapor into the badge and subsequent adsorption onto mated charcoal The authors deseloped the theoretical . rmeiples ot the badges operation, and discussed sensitivity ' temperature and pressure, face velocity effects, and .spotisi- time Preliminary results showing the badge's i.ipiinsc 10 benzene. eth \ I acetate, methy I ethy 1 ketone, and \rcne also were presented and were described as "very '.eonraging" (see T able II) In t he same sear. Si Is erstein reported results ol la bora tors d 11 eld test mg ol the G AS B A DCi E t or aery lonu rile The sulis ol the exposure ol 33 badges to known coneentraMis in the laboratory are presented in Table II. The results dieate the acceptability of the GASBADGE lor measureents tit aery lomtrile oser the range of 0.75 to 19 ppm The lie ot exposure in the laboratory was not given, however .Id measurements did cover periods of up to seven hours though temperature and relative humidity ranges vsete ported, data analysis to determine the elleets ot these irtahles was not presented Silverstein also looked at .`sorption eitieiencios and determined that the best results *4 percent) were obtained with lour niL ol two percent etone m carbon disullide. In 1478. Bamberger et at. conducted a series of laboratorv sts to evaluate the G AS BADGE Their approach involved `c generation of known concentrations ol solvents and ihsequent evaluation with charcoal tubes(aetive sampling) nd ihe passive dosimeter. To evaluate the applicability ol oe dosimeter over a wide range ol compounds, the investimon included seven different organic compounds each t resentaiive ol a diflerent functional group Included m ' siudv were benzene (aromatic), n-butanol (alcohol), n.uG acetate (ester), isooetane (alkane), methyl ehloroi m i halogen.ued alkane), methy I isobuty I ketone (ketone) 'ci trichloroethylene (halogenated alkene) The dillusion ief f icient ( D) used was that supplied by the badge munufac ter except in the case ol isooctane w hich was reported as , :ng an unknown coefficient Computations involving ms .ompound relied on the coefficient for n-octane A ' ariety ol experiments was conducted to look at a wide range "I questions. Their findings corroborated dosimeter com serns similar to those of active systems using charcoal tubes. e . minimum and maximum loadings are important, postimple contamination and loss can occur it the exposed bsorbent is not adequately sealed, percent recovery lor iixiures is consistent with percent recoveries for single impounds, and differences in charcoal lots can give difler.it results Other tests confirmed the need for some air 4 movement across the badge lace and the lack ol etlect ol temperature changes over a small range! I I "'C'l I he results ol the simultaneous sampling w uh the badges and the char coal tubes indicated that the badges had a consistent nega tive bias. The authors suggested that, because the results were so reproducible, corrections lor adsorption dosoi ption ellicicncies less than 100 percent can he accomplished ium .is is done lor charcoal tube data In 1974. Hirav ama and Ikeda cv aluaied I he appheai mn ol the GASBADGF lor monitoring exposutC' 'o mixed xolventx 11,11 Their research involved ditlcivnt preparations ol activated carbon "lelt" m place ol the supplied collection medium and exposure to mixl arcs ot n-hexane cthx I acetate and toluene Summary (graphical) data indieaiecl th.n the amounts ol contaminant absorbed bv the dosimeter were proportional to both the vapor concentialums and time ol ex pi'sure H.tllidav and Anderson repoited on the use oi the GASBADGE m monitoring loi It.noth.me 1 Six nbs.na tions indicated a ra nge ol men sure mem > 11 om minus i, me in plus ten percent ol the tesi atmospheres l nloi tuuatc lx the authors did not report iheir procedure lor ilcternunme ilv concentration ol halothane m the lesi aimospheies In I9XI. Evans and Horstmnn reported evaluations ol desorption ellicicncies ol charcoal tubesand the Ci ASB Al Ki F I or st \ rene 1 For liquid dosing t hey lound (he dusimeier lo h" similar to the luhe. vv hile lor vapor dosing the badge was sapermr The authors suggested that the dtllerenccs in '.suits min have been related to the use ol coconul shell . "bun in the uihes and petioleum derived carbon in the b.id ee Thev did not explain vv hy t his dil I ere nee w ould at I eel .in. method ol dosing and nvvt the other In 1980. Anders and Mullins ol the TIM Company pres. med results comparing the 3 M passiv e monitor withchjrv oa! tubes in sampling lor mixiures ol organic compounds'1,>' I ne laboratory lexis included a bmarv mixture of toluene and methyl ethyl ketone; a tertiarv mixture ot benzene, toluene and xv lene; and complex mixtures o| unleaded and leaded gasoline containing various alcohols Although the inv estimators cited "excellent" pieeision and accuracv tor the dilHision.il monitor, sample sizes were small, and the com plicated study design and lack ot rave data preclude the determination ol precision and bias statistics Mazur and his co-workers1"1 conducted side-by-side laboratory and field tests with charcoal tubes and 3M organic vapor monitors lo measure concentrations ol halothane (2-bromo-2-ehloro-l.l.l-trinuoroeihane) and enllurane (2-chloro-1.1,2-trifluoroethyl diHuoromeihvI ether). The results ol the laboratory studies are presented in Table 11 and support ihe authors' conclusions that the dosimeters are a reliable method for the collection of enflurane and halothane. In 1980. I autenberger et at, described DuPont's passive monitor lor organic vapors."" Each charcoal strip in the PRO-TEK G-AA Organic Vapor Badge contains approxi mately 300 mg of coconut-based activated charcoal impreg nated in an inert poly mer. A dual sampling rate of approxi- 3M 101546 Am /f*d Hy.' Assoc i M3) AuttuM 198? mutely 50 nr 100 nil min is determined by the removal of one or both ol the dosimeter's protective covers. One aspect ol t heir research inv olved experimental determination of (he dilltision coellicient ol several gases and vapors. They reported that values calculated hy 1 ugg'1' were within 10 percent ol their experimentally determined dilltision coelliciciH values. Preliminary experimental results were used to d iscuss lace velocity ellects. ranee and xensitiv ity. ma ximum and minimum sampling times, vapor retention, storage xtah1111v. desorption ellieienev. and overall badge efficiency I he overall accuracy determinations were limited to lour observations at each ol two concentrations ol carbon tetrachloride (see Tahle II) However, the presentation ol raw data, as well as an explanation o! the statistical tests applied, is most uxelul. I his same detail of inlormation is also lound in DuPont's validation report' lor toluene and benzene (sec fable II). 1 ' I n the ben/ene report. DuPont also describes its PRO-1 E K G-BB badge Ibis badge has a backup section ol charcoal, which serves the same purpose as the second section in a charcoal tube. i t1., to aid in determining il the sampler has been overloaded. 1 he a M Company also markets an Organic \apoi Monitor with a backup section.'1 ' In studies of the measurement of waste anesthetic gases with passive dosimeters. Jonas et ol. evaluated the GASBADGE, 3M Organic kapor Monitor and DuPont Pro-Tek in measuring enllurane. nl I'nlortunately. the badges were not identified in the presentation ol the results although interpretation ol the reported sampler geometry would indi cate that A was the Du Pont badge. B was the 3M badge, and C was the GASBADCiE. The results of their laboratory studies indicated that badge B had the lowest coefficients ol variation (CV was not calculated as described in this text) as compared to concentrations determined by infrared analy sis Badge A had a low CV (9 percent) at 5 ppm and a much higher value (CV = 34 percent) at 20 ppm. The C badge had consistently high CV's ranging from 23 to 30 percent. It should also be noted that the charcoal tube CV's ranged trom 11 to 27 percent, that desorption efficiencies for the badges ranged trom 0.81 m 1.17. and that IR analyses of tank concentrations were constantly lower than expected. If badge B was the 3 M dev tee. the results of Jonas el at. support those reported by Mazur ei al.'1,11 Further testing of badges A and C seems necessary, however, to confirm their seemingly low precisions. Mazur and his coworkers conducted additional tests comparing the 3M and DuPont badges against charcoal tubes ,<il Methyl chloroform and trichloroethylene, two sol vents widely used in vapor degreasing operations, were sampled. In the laboratory phase of the study, the badges and charcoal tubes were exposed to chamber concentrations over the range of 160 to 840 ppm of methyl chloroform and trom 20 to 200 ppm of trichloroethylene. Exposure times varied from two to six hours for methyl chloroform and trom lour to six hours for trichloroethylene. The laboratory work indicated that Che percent recoveries of the various doses (concentration X time) were in good agreement except for one exposure of the 3 VI badge which involved a five hour African tndustnal Hygiene Association JOURNAL /4j) $ a? exposure at 700 ppm. I he authors noted that this exposure of 3500 ppm-hours exceeded the upper expo uro limit pro vided by the manufacturer The overall mc.u. tecoverv value lor each type of sampler was used to correct all subsequent held data In addition to the recovery measurements, the laboratory phase ol this study also involved determination of storage stability The authors lound no significant losses of methy I chloroform or trtchloroethy lene Irom eithei badge following storage ot exposed badges lor up to three weeks In 1978. West and Rets/ner reported on the held tests ol the MI NT MON ITOR'* ( R E A E. Inc I permeation peisou.o monitor lor v inv I chloride " I hi' monitor was a modii ied version ol one previously described by Nelms cial"' I )u collecting medium was activated charcoal, but rather than rely mg on molecular diffusion, the hadge design inv olv etl a polv meric membrane and the permeation ol vinyl chloride through the membrane and adsorption onto the charcoal Initial laboratory calibration was used to determine the permeation constant ol the dev ice I ahortitorv results null eated good accuracies as summarized in I able II During the same period that Tompkins and Goldsmith were describing the GASBADGF. Bailey and Hollmgda!-' Smith ol Great Britain were presenting then ideas lot a personal passive sampler lor organic gases and vapors Their design involved the use ol either one ol two ty pcs ol membrane and subsequent adsorption onto activated char coal. They found two membranes to be sattshictorv one ol thin silicone rubber w hteh acted as a permeation ban icr and the second a porous polypropylene film which allowed lor molecular dilltision ol the gas and vapor They conducted laboratory tests using carbon tetrachloride, styrene and dichlorodilluormcthane. Their test results do mix some ter mmology. eg-, permeation rates lor both the permeation dev ice and the diffusions! dev ice. but did prov ide an eat lv demonstration of the feasibility of such a dev icc lot monitor tng certain organics The device, the Porton Dilltision Sampler, seems to see its greatest use in Great Britain acrylonitrile One of the newest applications of passive dosimetry involves the use of a porous poly mer ( Porapak - M us the collecting surface with subsequent thermal desorption and gas chro matographic analysis. Benson and Boyce have described such a device and its utility in sampling tor acrylonitrile Laboratory testing for aery lomtnle involved comparison ol the dosimeter values with concentrations measured on a gas chromatograph. Initial experimentation indicated that the dosimeter can be used for acrylonitrile concentrations in the range of 4 ppm. but at concentrations ol 2 ppm a 40 percent error is reported. aniline In addition to activated charcoal, another wtdelv used adsorbent medium is silica gel. To study the utility ol this material. Campbell and Kon/en constructed passive dosim eters trom glass culture tubes (1.05 cm inside diameterl with 40 60 mesh silica gel as the collecting surlace.1'"'1 Laboratory testing involved exposure of the dosimeter to aniline, with exposure concentrations determined by gas chromato graphic analysis of ethanol gas scrubbers. Three different 3M 101547 615 si?e (length) dosimeters were evaluated, with the best results obtained with the intermediate length tubc(L *= 3.0cm: A ' L = 0.3 cm) The authors present raw data and clearly described their statistical techniques. ethylene oxide Mullins and Anders ha\c recently described the 3M diffu sions! monitor for sampling ethy lene oxide in air,'M1 In this badg; the ci'liecting surface is described as a "chemically imprt en.in-d charcoal surface, (where) a reaction occurs produ, ir.r a stable compound with a sapor pressure sub* st.im 1 invf tnan the parent compound "The authors pn m i - i, ,iM\ summari7ed data describing the hnearits and,,- t he monitor, the recovery of absorbed cthx I- cnc . ' . onmenta! effects, sample stability. and the c 11 c. ' p filial interferences. Precision and bias are pies.:' , 1 . Mt 11 lorma'riehy ce Hodr.... i a have described another 3M diffusional monu>- k '.'"inline formaldehyde IMl In this diffusional moniii ' r: v i.iiecting surface is an "impregnated sorbent" which wit iti.r; he desorbed m suu with water and the conceniratu'r ol formaldchydcdetermined colonmctncally l.ahoratot s e . a luation first invoked determination of recov ers coeiiments which at eight ppm-hours (19.5 micro gram' i sicre found to be 1.00 0 04 over six tests. The next step imm\ed determination of the dosimeter's "sampling ran" IDA I ) hi exposing the dosimeters to "known" con centrations ol formaldehyde as generated by a permeation tube The efiect ol relative humidity on the sampling rate also was investigated, and evaluation of the data did not indicate any statistically significant differences between the rates at 50 and 85 percent relative humidity. The study protocol then inv olved simultaneous exposures of inrpingers (modified chromotropic acid method) and dosimeters The authors concluded that "the measured values by both methods lie within r 25 percent of the expected response" and thai "less variation is observed in the monitors than in the impmgers " However, neither precision nor bias were reported The authors also investigated effects of storage and determined that at elevated temperatures (38 C'C) losses up to 1 I percent occurred alter one week, however no stgnilicani loss was seen lor samples stored at 23 C. The authors hricfiv discussed the potential for a negative interference from phenol and described the use of modified calibration curves to address this problem. DuPont's PRO-TEK series of colorimetric Air Monitortr - Badges, includes a badge for formaldehyde The collec tion principle involves a chromotropic acid-sulfuric acid reaction laboratory evaluation (42 samples) of the dev ice at seven exposure levels revealed results as shown in Table II Additional studies also were conducted on tempera ture and siorageeffects The raw data and statistical analysis procedures arc presented, Kriesel'1'*' has described a new passive dosimeter for form aldehyde which is a modified vetsion of the Palmes tube. At the pi esent time experimental data concerning this dev ice are not available 616 phosgene Matherne et ol. have recently described the GMD. Inc "passive dosimeter" which prov ides a semiquantilativc mea surement of phosgene exposure.,5`' The badge involves direct contact between the contaminated air and a chemi cally impregnated tape and therefore does not rely on a stagnant air layer. The treated paper stain intensity is reported to be logarithmically proportional to the phosgene dose over a range of 2 to 100 ppm-minutcs For quantttut iv e measurements the badges can be read colorimctricallv other methods Hill and Fraser have described the use ol commercial den-' tor tubes modified to act as passue dosimeters In tin u research, common lencth-of-sta in detect or tubes w ere mod i fied bv cutting ofl the eonical end ot the tube and lemnv me some of the indicator column mater lal T his leav es an m it a with a cross-sectionaI area equal to that ol the inside o: un tube and a path length determined by the distanee Irani tIk end ol the tube, to the beginning of the indicator maivn.il One would expect, however lhal as the sorhem ni.nviia, becomes exposed, i.e., the length ol Siam increases, the diffusion path length will also increase, thereby changing the sampling rate. Their evaluation of these devices involved separate laboratory exposures to toluene, ethanol and nopropanol The results of their work, although presented onlv in graphical summary. demonstrate the potential lor the use of modified commercial detector tubes as passu e dosimeter s field validation Relatively few studies have been published in whieh p.i'sive dosimeters have been compared side by side with chaicoal tubes or other conventional sampling methods under actual field conditions. For inorganic compounds only two stud ies. involving nitrogen dioxide'"**' and chlorine ' have been identified For organic compounds, eight stud- ies': **311 ,J Jt> M have inv olved field comparisons with ihe number of compounds per study ranging from one to 22 In three of these studies, statistical analvscs ol data were not presented and cannot be performed because ol small sample size or insiilliciem presentation of data Tones et a/1*''1 conducted a field evaluation lor NO., in a salt mine, which contained diesel equipment as the NO. source. At each of 16 different fixed area locations, two Palmes dosimeters and two TEA tubes with pumps were used to sample the atmosphere The acme sampling (pump) method gave a coefficient of variation (CV) of ft 7 pereem while for passive tubes the CV was 5.8 percent. Regression analysisfu here the active sy stem was the X variable) of their data gives a correlation coefficient of 0,69. a slope ol 0,59. and an intercept of 2.05 ppm for data over the range of 3 ~ to 5.5 ppm as sampled by the active method This indicates that the dosimeter gave consistently higher readings which is reflected in the means for the two methods 4 51 ppm loi passive and 4.14 ppm for active sampling The authors did not report wind velocities, but low velocities, as would he expected with area samples, should have caused passive 3H 101548 Aw tnc Hyp Asicx J (3 values to be low as compared to active values; this was not the case. On the other hand, high face velocities could have led to the observed positive (passive versus active) bias. Hardy ei alm' reported the raw data results from a Held evaluuuon of a permeation chlorine monitor (REAL. Inc.). Thirteen comparisons were made in which the results from a batters operated pump and an impinger sampler were com pared with the measurements from either two or three per meation samplers. To further evaluate their results, the in\estimators performed a regression analysis using their pi. rmi.ition sample means for each comparison as the d. pi nd. nt \ariable. The results are quite good with a correl.-.i mi. 11., fficient of 0 95. a regression slope of 0 85. and an iro 111 pi of 0 15 over a range of 0.05 toll ppm as detected h, ilu impinger. It should be noted that with five impinger '.ample'nt less than0 I ppm. the corresponding permeation dev it e - di tected considerably higher concentrations (0,16 to 0 4 ppmi SiketvicmM'" reported field results for acrylonitrile moni toring uving 18 paired samples of GASBADGE passive m<'n11mv and active systems (charcoal tubes and pumps) over a rangc of 0.8 to 5.8 ppm as determined by the active met hod 1 he differences in results using the active system as a reference ranged from --0.7 to 1.5 ppm The difference in me a ns. 2 18 for the passiv c v ersus 2.75 lor the activ e system, was 2`i percent. Further data were not presented. W est and Reis/net reported five sets of field results for v tnv I chloride sampled with permeation dosimeters ( R E Al , Ine ) and charcoal tubes'*' Further interpretation of their results is presented in la hie III. In each case data for the active system are the X values Fout of the correlation coefficient values are very near one. reflecting good correla tion. however, the slopes show quite a large degree of varia bility (0.69 to 1.51). indicating that badge values may fall either well below or above charcoal tube values. In those cases where the slopes were less than 1.0. very high humidi ties (67 to 91 percent) were reported by the authors. This factor may have interfered with permeation, although the authors reported that humidity had no effect in laboratory validations; hence the variation in slope remains unex plained The authors noted that the overall field results showed that the badges had a slight positive bias Hickey and Bishop exposed 78 pairs of side-by-side char coal tubes and 5M Organic Vapor Monitors to complex mixtures of organic chemicals in tire manufacturing opera tions."" Generally the sampling period ranged from three to TABLE III Regression Analysis of Vinyl Chloride Field Detec> N Range (ppm) r (Slope Y-Intercept 7 002-1 0 99 1 19 8 0.08-1 8 0 99 069 12 0.02-6.9 1.0 1.31 39 0 05-1.8 0.82 0.81 24 1 48-16 7 096 1.08 0 03 0 05 0.01 0.11 043 Amtrtcin tnduvlnii Hygirnr Association jOURNAl (431S/8? five hours, and most observations consisted of one momtni and the lime weighted average concentration Horn two sequentially exposed charcoal lubes Sixty-four o! the setwere personal samples, while the remaining 14 were aie.r samples. The samples were collected in two separate piano (30 sample pairs in one plant and 48 in the other) Ot the 22 organics potentially available for analysis. 10 were detecicc over a sufficiently wide range of concentrations to allow tor appropriate statistical analysts by linear regression Tht results are interesting in that in the first plant. 9 of the If organics measured by the dosimeters showed higher vapoi concentrations as compared to the charcoal tubes, w hile it the second plant only three substances had a regression vlup, greater than one. The combined data for both plants did no: indicate that the passive system was consisientlv bi.tvcd when compared to the active system The authors did point out that generally the Y-intercepts O^passive dosimetci data) were slightly negative, a finding w htch may indicate a lack of sensitivity on the part of the dosimeters at low concentrations. For the remaining 12 compounds paired t-tests revealed no significant difference between the ch.n coal tube and passive monitor means ai the 95 percent confidence level. The use of t-tesis to analyze such data ha' been questioned since the means of the two methods mav be very similar but the components of paired values can be considerably different.'19'This condition can only be revealed through regression analy ses. In 1980. Mazur ei al.1**' reported limited field data lor halothane and enflurane measurements using both 5M Organic Vapor Monitors (OVM) and an active svstem (charcoal tubes and pumps). For halothane three paired samples were reported. The mean concentration for the active system was 2.01 ppm while 1.9 ppm was reported I or the OVM. a difference (relative to the active sy stem) ol five percent. Only one data pair was reported for enflurane 0,49 ppm for the OVM and 0.52 ppm for the active system Obviously, more data are needed to draw conclusions regarding a comparison of the two methods for these agents A second study by Mazur ei al.'**' reported field compar isons of passive dosimeters and active systems (pumpv and charcoal tubes) in sampling for trichloroethy lenctTCTland methylchloroform (MC). Both DuPont PRO-TEK and 5M Organic Vapor Monitors were used for the passive svstemv Personal samples included exposure of one each of all three monitors. Area sample results involved threeaverage values: one was the average of three charcoal tubes, and the other two. the average of two of each type of dosimeter. For MC. 11 personal and 7 area data points collected over time peri ods of I to 5 hours at 15 to 21 C and 35 to 40 percent relative humidity were reported. For TCE. 22 personal and 7 area data points collected over periods of about I to 6 hours at 18 to 24 Cand 30 percent relative humidity were reported A regression analysis in which the charcoal tubes were the independent variable was reported by the authors 1 n each of the following data sets the presented values involve TCE personal and stationary sampling followed by MC personal and stationary sampling. For the DuPont badge, regression 3H 101549 *17 slopes of 1.0. 0.99. 0.99. and 0.98. and correlation coeffi cient s of 0.98.0.98.0.94, and 0.94 w ere obtained. For the 1 M badge. repression slopes of I 08. 1.06. 1.07. and 0.90, and correlation coefficients of 0.98. 0.98. 0 98. and 0 90 were determined These \ a lues appear to be quite pood, however, the authorsdid not report ifthey tested the statistical sigmfi;ance of these values The> also did not report aserape of lace velocities associated with stationary samples. F vans ei a/I60' of Great Britain reported field validation data for the Porton diffusion device while measuring methyl Mhvl ketone Iri this case the conventional sampler was a pump and a cassette fitted with a charcoal cloth similar to ihai used m the Porton device A repression analysis per formed with then d;ua showed pood correlation ((>9) and good slope (0 9). however, the intercept value (4 09) indi cated that at low concentrations, the "home-made" dev icc pave lowet values than those determined with the conven tional monitor Concentrations reported for the conven. mnal dev ice ranged front I I to 189 ppm Henson and Bovce1"'" field tested the Monsanto Poropak \ deuce in Gieat Britain Conventional samplers consisted of pumps and Poropak N polymer tubes. Sixty-fivc pairs o! -antplcs were obtained, and the range of acrylonitrile mea sured b\ the tubes was 0,1 1 to 2 1.65 ppm Repression analys is of their data indicates only fair correlation (0.6.1). a low lope (0 46). and a negative intercept ( -- 2.06). These values tppear to result Irom the apparent inability of the passive cv ice to accurately detect concentrations less than 0.5 ppm Also, comparisons between values over the lower half of oncentrations sampled showed considerable scatter 1 he final field study to be discussed suggests perhaps the nosi senous discrepancies resulting from use of charcoal rassivc dosimeters,161'This study was performed by NIOSH sersonnel in coniuncnon with industry-wide studies of ihc fry -cleaning, screen printing, and boat manufacturing indusries. and also included one viscose rayon and one cellothane plant Carbon disulfide, pcrchlorocthy lenc. toluene, net hy lisohuty I ketone (MIBK). styrene, and acetone were amplcd using the ?M OVM. the GASBADGE. and active y stems with charcoal tubes. The presentation of the study design is not clear, but it appears that area samples inv olv ed aii three devices while personal samples involved charcoal ubes and only one of either passive dev icc. In that this study nvoives six compounds in 64 plants, the volume of data is (Uitc large In addition to regression analysts, paired t-tests nJ Vv ileox signed rank tests were performed by the authors o determine equivalence of data sets. As noted earlier h. u.e of i-tests for determination of equivalence has Per questioned "<1 1 able IV show s the primary results of this study, As can be seen, the range of correlation coefficients (r) for most com pounds was quite large. Although 12 plants were sur- eved for toluene and MIBK. the data ere grouped vgether. and therefore ranges of the correlation coefficients ould not be determined For carbon disulfide, one plant as snrveved w ith the OA'M and GAS BADGE, and one was urveyed with the GASBADGF only. Foi the ranges of r . ported in Tabh IV. the uppei values are quite acceptable. 0 with the exception of carbon disulfide using the GASBADGE However, the correlation coefficient for carbon disullidc using the OVM was 0.95. The correlation data can be summed up as being extremely variable. Table IV also reveals that concentration had an cflect on the correlation coefficient for three of the compounds, though this was true for both monitors only when measuring acetone concemrations Regression slopes were as variable as the correlation cocflicicnts The authors tested the slopes to see it they were significantly different from zero, and lor accioneand carbon disulfide a difference could not be demonstrated for sevcrul of their data sets This indicated that thri e was no iclation ship between the results obtained w ith the arm e s\ sicm and those obtained with the passive dosimeter For othei com pounds. it vv ould hav c been use I til l o test the difference ol t he slope from one. which il not signilicantlv diflerent would indicate agreement of the two methods In tests of equivalence of data sets, the authors noied that for all plant data combined only toluene showed euu.ilitv and this for the charcoal tuhe-G AfsB ADGT (CT-GHl com parison However, when results from individual plants aie used, the comparison outcomes are quite variable Foi pcrchloroethylenc. equality was reported for one of three CT-BG comparisons and for one of two CT-1M sets For stvrcnc. (wo of six CT-GB and no CT-TM comparisons showed equality. For acetone, three of five Cl -1M compari sons and one of six CT-GB data sets showed equahtv In addition. GB-OYM comparisons showed equality inbol I7 comparisons It is ohv ions that repeatability was not demon strated in this study. Whether the problem involves the dosimeters, investigative ot laboratory techniques, and oi env ironmental conditions cannot be determined. In the only other field study of more than one plant, Hickey and Bishop16' aKo reported some problems with the consistency of observations These limited results clearly demonstrate the need for additional field studies of passive dosimeters as compared with siandard monitoring techniques discussion Passiv e dosimetry (monitoring) is a rapidly dev eloping technolocv as witnessed hy the ptoliferation of devices and applications since Palmes and Gunnison introduced iheir concepts just under ten years ago.1"'1 The latest entrv into the field comes from the MSA Company and involves an adap tation of iheir lengih-of-stain direct reading tubes lor inor ganic gases,fiJI which incorporates the application of molecu lar diffusion and a chcmicallv impregnated paper as the sampling medium. Although research results are not availa ble. as a first approximation one might assume that these devices have precisions and biases similar to those of con ventional detector tubes. For any new technology to be accepted and used hv piacticing professionals, the development of a body of knowl edge demonstrating efficacy is necessarv With env ironmen tal monitoring techniques, the determination of the efficacy usually starts in the laboratory and culminates in the field In the case of passive monitors, a body of know ledge hysed on laboratory testing is rapidly being developed Of the van* 3M 101550 Hyf t'W 19E? TABLE IV Major Results of a Field Study for Organic Vapors'*1' Concentre tion Substance Comparison Overall r Range of r Dependency Pprchloro ethylene Styrene Acetone Toluene MIBK cs CT-GB CT-3M CT GB CT-3M Ct-GB CT-3M CT GB CT3M CT GB CT 3M CT GB CT 3M 0 62 086 0 82 0 76 0 38 0 45 0 80 0 91 0 88 0 79 0 30 0 95 0 62 -0 99 0 84 -0 94 0 65-0 97 0 48-0 86 0 36 0 86 0 25-0 83 NA NA NA NA 0 03 0 3B NA Yes Yes Yes Yes ablcs thiit have been studied. threeappear lo uniquely allcct a diffusion monitors accuracy in measuring airborne conccntiations of gases or vapors. The most important factor appears to be determination ol the contaminants' diffusion coefficient (01 the sampling rate when the dosimeter's geometry is also considered), the wind velocity at the dosimeter lace, and the relativ e humidity of the sampled air A' discussed eailiei. there are also a variety of potential sources of emu. such as interfering contaminants, sorbent c.ipa city and problems associated w ith analy tical determina tions, which aie common to both passive and active meaxurcmeni techniques I a botatory detei mination of sampling rates ( DA l ) for a specific monitor and a specific contaminant are important and are being provided by several dosimeter manufacturers lor an ever increasing number of compounds. Once an appiopriaie sampling rate has been determined, corrections lor field use. specifically for temperature variations, can be made 1 he mam problem vv ould inv olve situations where the en\ ironmental temperature fluctuated widely (more than 25 c C) and went unnoticed, a very unlikely condition. 1 he research on ef fects of face velocities demonstrate that lew pioblems should be encountered where dosimeters are worn by workers as personal monitoring dev ices.11 24 2,1 Ul "I heir use as area monitors should be carefully evaluated to ensure that stagnant atmospheres (velocities less than 7.5 cm seclarc not involved. High wind vclocities(ai least what would normally be encountered in the workplace) or wind direction do not appear to have adverse effects on dosime ters with wind screens. Of greatest concern as a result of rev icw ing the literature on laboratory testing of passive dosimeters is not the results but rather the thoroughness of their presentation. As dem onstrated in Tables I and II. where statistical analyses arc presented by researchers, or where sufficient data are pre sented to allow the reader to determine bias and precision, the rcsultsare very encouraging. Unfortunately the presentation ol experimental design, as well as sufficient data and or statistical analvxes. are often lacking. This is true lor some individual researchersas well as lor several manufacturers o the dev ices, especially those for inorganic compounds If om recommendation regarding laboratory testing is made, i would he that those researchers inv olv cd in the evaluaiion o passive dosimeters in the laboratory take the time to repot the conditions of their experiments especially equipmen used and procedures lor determining "known" concentro tions. and as much detail about their icsults as possible I summarized data arc presented, the aulhoi should presen the known concentration at each level, where levels an determined by concentration and time thi number of obsei v at ions mads with passiv c dosimeters and t he a v crage vain and standard deviation ol thi icsults Statistical an.ihsiagain at each lev cl levied should involve detei minai ion o the coefficient of vananon (prevision) and the bias a described in equations (7) and (hi respectively Once ill evalua lions are made at the v a nous test lev t is i iu detei mi nation of a pooled precision and bias is appiopriaie li addition to these measurements, rcseatehcrs may als, choose to pi event an ov eta II w ste m act ur.it v I o develop , belter undeistandmg ol appropriate staiistie.il technique and their application to passive dosimetry a review o' I.autcnbergcr el al. is recommended 11 For most active momtoiing svstems used in indusina hygiene the random sampling ettor is usually associated with the pump and is traditionally set ai z 5 percent li many cases, especially loi the measurement ol otgann ' vapors, the analytical pioeeduies and eonseqiu mIv thee associated errors are eq m v a lent lot hoi h passiv c a nd act iv. systems Nevertheless, both svstems have landom cnoi consequent Iv. one should not expect perfect agieemem id the results ol comparisons obtained undei held lest tondi tions Another laclor complicaiing the evaluation ol held results is the greatly increased possibiluv lot the intiodtiv non ol operator, or sy stematK ei i ors Since acuv e sy stems require mechanical pumps tin potential loi opeialoi eimi would seem lo be greater than lor passive svstems Overall, it is apparent that existing held observation comparing passive dosimeters with standard moiuloimi met hods at e highly v aned \\ hile some si tidies demonsi i an good correlation and slope. "1" oiheis show onlv good correlation. ' or are cxtiemely v at icd lor both catcgoi ieCollectively, these references neither support not icluir tin use of passive dosimeters Certainly en\nonmenial luctotaflect acme systems as well as passive systems. In theorv. a case can be made that environmental factors <wmd and humidity (affect passive sy stems in the greaiest extent, w bile temperature and pressure sanations mosl greailv alien active systems. On the other hand one can also state that poor experimental quality cont rol mav afleci sin. h lactoi s acontamination, time measurement eiroi. and analytical error. Of course, chemical interferences may aflect both systems As with laboratory expci mu tilation. tecommendaiioiircpnrding the field testing ol passive dosimeieis involve a plea lor better reporting of both held conditions and n-suliofanalysis. First, for both person.il and area monitoring, the estimation and oi measutemeni of fate velocity is intpoi- AfDFficjr industrial H\penp Association JOURNAL M F 17 3M 101551 ta-nt. Of equal importance is the reporting of airborne con taminants other than the one(s) of interest and environmen tal variables including temperature, pressure, and relative humidin along with information as to their variation over ,hc period of observation. Again, if raw data cannot be presented, the reported results for each level tested (X value us determined b\ the standard method) should include the lumber of observations made with passive dosimeters, and heir associated mean and coefficient of variation. Statistical '-valuations also should include a regression analysis of the .lata as outlined earlier. Undoubtedly, additional research is needed on the effect of not considering the error associated sith the supposedls independent (X) variable. In sum mart, passis e dosimeters show great promise as an important tool. The results presented in Tables I and II .ndicate that the precisions of the dosimeters are essenualh equnalent to cons cntional techniques and in mans casesthe additional fisc percent error associated with mechanical umps makes passive dosimeter systems esen more attracisc This, coupled with their ease of use, lack of required laintcnancc. acceptance by w orkers due to light weight, and innecessars calibration make passive dosimeters cxtremcls dsantageous Certainly they will not replace consentional nethods. as these hase their place, especially for area sam>ling The continued and growing use of passise dosimeters, owescr. should generate additional data documenting their diabilits and eliminating doubts about their usefulness. cknowledgement he assistance of Dr. H Kenneth Dillon. Head. Industrial Isgicnc Chemistry Section of Southern Research Institute, n critically review ing this paper is gratefully acknow ledged. eferences 1 Tompkins. F.C. and R.L. Goldsmith: A New Personal Dosimeter tor Monitoring of Industrial Pollutants Am Ind Hyg Assoc J 35,371-377(1977) 2 West, P. W. and K.D. Reiszner: Field Tests of a PermeationType Personal Monitor for Vinyl Chloride Am Ind Hyg Assoc J 39 645-650 (1978), 3 Lugg, G.A : Diffusion Coefficients of Some Organic and Other Vapors in Air Ana/ Chem 40 1072-1077 (1968) 4 Montalvo. J G . Total Elemental Content Passive Personal Monitors Am Ind Hyg Assoc J. 40 1046-1054(1979) 5 3M Company Organic Vapor Monitor Sampling Rate Vali dation Protocol St Paul. MN 5 Jonas. L.C.. C.E. Billings, and C. Lilis: Laboratory Perfor mance of Passive Personal Samplers for Waste Anesthetic Gas (Enflurane) Concentrations Am. Ind Hyg Assoc J 42 1 04-111 (1981) 7 Woebkenberg. M.L.: Current NIOSH Research on Passive Monitors In Proceedings of the Symposium on the Develop ment and Usage of Personal Monitors for Exposure and Health Effect Studies, pp 27-33 Evironmental Protection Agency, EPA - 600/9-79-032 (1979) 8 Environmental Protection Agency: Laboratory Evaluation of Commercially Available Passive Organic Personal Moni tors Contract Number 68-02-2686 ) Hickey. J.L.S. and C.C. Bishop: Field Comparison of Char coal Tubes and Passive Vapor Monitors with Mixed Organic Vapors Am, Ind Hyg Assoc J 42.264-267 (1981). o 10. U.S. Department f Health. Education, and Welfare: Doc umentation ol NIOSH Validation Tests. NIOSH 77-185. Cincinnati (April. 1977). 11. Lautanbargar. W.J.. E.V. Kring, J.A. M rello: A New Per sonal Badge Monitor for Organic Vapors. Am Ind Hyg Assoc J 41 737-747(1980) 12 Bamberger, R.L..G.G. Esposito. B.W. Jacobs. G.E. Podoiak and J.F, Mazur: A New Personal Sampler tor Organic Vapors Am. Ind Hyg Assoc. 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Field Compar, son of Two Passive Organic Vapor Sampling Devices to the Charcoal Tube Presentation at American Industrial Hygiene Conference. Houston, TX (May 18-29, 1980) 62. McKee, E.S., P.W. McConnaughey and I.M. Pritts: Colon metric Personal Dosimeters for Some Inorganic Contami nants Mine Safety Appliances Co , Pittsburgh, PA 29 December. 1981. Revised 8 February 1982 American Industrial Hygiene Association JOURNAL (431 S BP 3H 101553 621