Document 5D2xM6wDgg0n7qbmkLZ9x63RN

Am Ind Hyg Assoc. J 43(8) 605-621 (1982) The history of development and validation testing of passive dosimeters is reviewed. Theoretical consideration including possible limiting factors or interferences, are presented. Laboratory and field validation tests at critically reviewed and results ar presented for comparative purposes. Evaluation of available data indicates th< passive dosimetry, with some exceptions, is an acceptable method for monitoring gasses and vapors. Mo 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 m Birmingham. Birmingham. AL 35294 introduction Recognition. c\aluation and control arc the cornerstone;* of the application of that mixture o! science and art know n as industrial hygiene. These three tasks, howcv cr. are no longer personal passive dosimeter: personal, because it can be wo: by the worker in close proximity to the breathing /onv passive, because there is no pump to move the air over the eminent domain of the industrial hygienist. In the past collector, which equates to fewer calibration and mainu decade, a proliferation of training in the recognition of nance problems. Some quarrel with the term dosimeter, wn workplace hazards has been made widely available to purists preferring to call them collectors, monitors, o workers and management alike. At the other end of the samplers. While many of the devices are collectors an spccu um has been the training of indtv iduals highlv special require the application of subsequent analytical proced ure ised in (he conirol of specific hazards, especially those others prov ide for a more direct measurement of'Y.xposi.r in\ ol\ mg noise and toxic air contaminants. These dexclop- dose." Their basic appeal, however, is simplicity ol ii'v ments are w clcomed because they contribute significantly to Theoretically, elaborate calibration procedures arc unnece- the ultimate goal of protecting the health of workers by sary. and all that is needed is a fairly reliable timepiece t providing safer and more healthful workplaces. measure exposure duration. There is some recognition the At the same time, professional industrial hygienists rec ognize that often the critical step in the process is not recog nition of toxicity , but evaluation of hazard which leads to the subsequent development of the most effective means of temperature and humidity may affect the observationtherefore, most manufacturers advise the user to report thes environmental conditions to the analytical laboratory pro cessing the dosimeter. control where warranted. This key step of evaluation is the Rather than view ing passive dosimeters as another wav t. unique domain of the industrial hygienist, often supple replace the industrial hygienist, industrial hygienists mu- mented by other members of the occupational hcahh and recognize and appreciate the potential of the dosimeter' it salety team. Where evaluation requires the determination of helping to achieve the hygienists' goals. That potential i w orkcr exposure to airborne toxic substances, the industrial significant in that personal dosimeters, if properly usee hygienist has seen a rev olution in the development of sophis offer the opportunity to revolutionize the evaluation step ticated techniques and equipment. The parallels with detector tubes, as well as with noise am The "organ-grinder" impinger sampler is a relic, hav ing been replaced hy constant flow. eight-hour battery-operated pumps, light enough to be carried by the worker. The liquid buhbler and impinger have been replaced by 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 w here the industrial hygiene staff required the addition of someone with a Ph.D. in electrical engineering, a new ionizing radiation dosimeters, are obvious. Indeed, th parallel with radiation dosimeters, especially Him badges t striking. The opportunity to significantly expand the me.i surement of worker exposure to many loxic materials ca: provide a quantum leap in our ability to provide sale ar. healthful workplaces. With any sampling device, however There also must be the understanding that use ol such dev ice is only one part of the evaluation step. The eoneepts o proper selection of workers at risk: the understanding o limitations, interferences and similar factors, and ultimate!1 the proper interpretation of the results ate still* key ingr. dients in the evaluation step. 1 he possibility ol "tal'C neg. live" decisions leading to erroneous assumptions ol sale: , or "false positive" conclusions leading to unwarranted expenditures of resources lor controls, still exists legardles. device has appeared which has the key of simplicity -- the of the measurement device used. Co0v"0h> 198? Afn***n tndMST'<i Hv0**n** A$VfVi*t*vf' can Indu&lw1 Hyg*pnp Association jQURNAt (43} 8 82 3M 111060 6C With the rapid proliferation of passive dosimeters in the past several years, it is appropriate that industrial hygienists - evaluate the "state-of-the-art"and. as professionals, become involved with the proper application of these monitor- devices. theori s of operation In that passive dosimeters by definition do not use an air mov ing dev ice to transport contaminated air to a collector, natural forces are relied upon to ensure that a representative amount of contaminant is "seen'" by the detector. To date, one of two principles has been applied in the design of dosimeters. The first, and most widely used, is the principle of diffusion of contaminant molecules through a stagnant gas (air) laser. The second principle involves the absorption in and subsequent pemwatitm of contaminant molecules through a membrane. DiffusionaI monitors rely on the movement of contami nant molecules across a concentration gradient which for steady-state conditions, can be defined by Kick's hirst l aw of Diffusion '*' \\ = -IlA=dci d\ (1) where: W = mass transfer rale, ng see. D = diffusion coetlicient. cm"' sec. A = cross sectional area of diffusion path. cnr. and dc dv = the instantaneous rate of change in concentra tion over diffusion path, (ng cnv'jcm '. ^^Kmsidcring the change in concentration (Ci -- C) over the total dillusion path length (Xi -- X,. = -- I.), equation ( I) becomes. A w = n -- tCi - c,,) (2) where. 1. = length ol the dillusion (static) path. cm. C|= ambient concentration of contaminant, ng cm1, and Cn -- concentration of contaminant at collecting sur face. ng cm'1. II an effective collection medium is employed.the contam inant concentration at the surface of the collector (Cn) can be assumed to he zero, and multiply ing both sides of equation ( 2) hy time, y iclds M = D -- (C ) I (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 ^fi^ind A. di \ ided hy 1. are cm1 sec. w hich are the same units ^^Poeiated with active air-moving devices such as personal sampling pumps. 606 Rearranging equation (3) as follows: ' Ml " DAt it becomes apparent that live lactors affect the measurement of the ambient air concent rat ion of a substance (C () 1 wo ol the factors (l and A) arc physical parameters associated with the construction of the dosimeter, one ( M) is pros ided by measuring the total mass of contaminant collected hy the sampler, another is the duration (t) the sampler was exposed to the contaminated atmosphere, and the final factor (D| i,, an individual property of each vapor or gas. It also ,, known1" that the diffusion coefficient is directly propoitional to the absolute temperature (T) of the vapor, raised m three-halves power and inversely proportional to the atmo spheric pressure (P). Dosimeters that rely on the principle of pernwaium through a membrane are especially useful vv here the contam inant of concern is usually found mixed with other interlei ing 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 ol interest and impermeable to most other components in ihe atmosphere, and or the collecting media. The determination of ambient concentrations of a con taminant using a permeation dev ice can be determined Iron, the formula: C = wk t (6) where: C = concentration of contaminant, ppm. w = mass of contaminant collected, pa. k = permeation constant, ppm-hours pa. and t ~ exposure time, hours. The permeation constant (k) is determined experimentally and is a function of the specific membrane material and contaminant of interest.1'1 sources of measurement error The most obv ious sources of error for both ty pes of passive dosimeters are 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 arc at least nine prediction methods for calculating the diffusion coefficient, and in one study 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 thv observ ed.'3' Montalv o has described a procedure tor limb mg errors associated w ith computed diffusion coefficients. At Am Ind Hy( Assoc 1 (A3) aueui; tss-` 3M 111061 least one manufacturer, the 3 M Company, makes available its procedures for determining sampling rates (DA. L) for its badges.' " Its approach has been to experimentally determine the sampling rate for Cite or six compounds in a chemical family to establish the relationship between the diffusion coefficient and the measured sampling rates. Sampling rates for other compounds are determined from the diffusion coel I'icicnts calculated by the Hirschfelder equation and the empirical relationships developed from the test compounds. The rationale for the selection of the Hirschfelder equation is not given, but in the study of the nine diffusion coefficient formulas, the author concluded that for higher molecular weight compounds the Hirschlelder, Biard and Spat/ equa tions were in closest agreement with determined values.131 Ku the permeation monitor, accurate determination o( the permeation coelficient lor each monitor is necessary for obtaining accurate results. Factors influencing permeation include: thickness and uniformity ol the membrane, affinity ol the membrane lor the analyte, swelling or shrinkage of the ntemhiane. and possible etching by corrosive chemicals. Considering temperature and pressure, and referring u equation (5) it can be shown that a temperature rise from 5 it 35 C would give a 16 percent increase in the diflusior coefficient, while a rise in barometric pressure trom 710 it 810 mm Hg would cause a 14 percent decrease However at the same time, the changes in temperature and pressure also arc affecting the concentration (mass v olume: actually density is the proper term but most authors use concentra tion) of the contaminant in that concentration is inversely proportional to the temperature and directly proportional tc the pressure. As a result, the total mass (M) collected by the dosimeter is only slightly affected by temperature ( M * 1' ' and is independent of the pressure."1 Consequently. w hile a i ambient temperatures, the diffusion coefficient will increase about 0.5 percent pcrC. and the total mass collected hy thi sampler will increase less than 0,2 percent per C Therelote a temperature change from 25 to 30 C. if uncot reeled, wi! introduce a measurement error of less than one percent while a change front 5 to 35 C, if uncorrcctcd. woulc introduce an error of about five percent. 1 he piohlems associated with accurate determinations of the mass ol the contaminant collected arc similat to those The final source of error to consider is the velocity ol I hi air external to the dosimeter: often this is referred to as lace involved with other collection devices such as charcoal or silica gel tubes, or to those in which the collection of the contaminant inv olves a chemical reaction with thccolleciion velocity. In an early assessment of face velocity eflccts. espe cially the lack thereof. Tompkins and Goldsmith point ou; that the important consideration is to contain all rcsisianci medium, (sing known amounts or concentrations of con to contaminant transport w it hi n the stagnant air lay er inside taminants to determine collection and or desorption effi ciencies is as critieaI a step lor passivc dosimeters as it is for other methods ol collection Saturation of the sorbent as well as the subsequent accuracy ol analy tical techniques are the devicc.'1, As Jonas el al. subsequently noted, the lace velocity directly aflccts the concentration gradient C :-- Cm in equation (2). and Cj can no longer be assumed to he the ambient concentration when the air external to the badge i* also pan of the total error associated w ith the measurement. stagnant.'61 With zero or low face velocities, the length (I l ol I Another common concern in all types of environmental measurements is the potential lor imcrtcrcnccs. either posi tive or negativ e. I rom other contaminants in the sampled air. the diffusion pathway is effectively extended, and there is a decrease in the measured ambient concentration. In Tompkins' and Goldsmith's work with the GASBADCif'". As the evaluation ol passive dosimeters has matured, they determined experimentally that as long as lace veloci i increased attention is being paid to possible interferences in nuilti-eontammant exposure situations, in both the labora ties were greater than 7.5 cm sec (15 fpm) there was "no significant effect on dosimeter response:" however, experi tory and field. In evaluating such interferences it should be mental results supporting this conclusion were noi pre- 1 recognized that there are several potential sites for such interferences to appear, c.g.. effects on adsorption or absorption efficiency ol the sampling medium, chemical sented."1 High face velocities may also affect the concentra tion gradient. Commercially available dillusion device* rely on either a large ratio of diffusion path length to dillu a teuctions ol tw o or more contaminants prior to analysis, and the multitude of interferences associated with analysis of complex mixtures of gases and or vapors. These problems sion tube diameter or a wind screen to limit error* from this condition. One of the most comprehensive te*ts to document source* also arc found in the more classical sampling and analyti of error has been conducted under contract lor the Nanona I cal methods. Accurate measurement of the time the sampling device is Institute for Occupational Safety and Healih. and although cancluded. it is not yet available as a public report 1 he exposed, is essential to most industrial hygiene sampling study involved evaluation of the GASBADGf and 3M Organic Vapor Monitor'" (the DuPont badge not being 1 procedures. For both short-term and full-shift exposure measurements, errors less than one percent, i.e. 9 seconds in available at the time the study wa* initiated I via challenge with several organic vapors. The factor* investigated were 15 minutes and 4.8 minutes over 8 hours, are not unreason precision, effects of storage, maximum and minimum level* a able goals. For the diflusion coefficient and possibly the permeation of quantification, face velocity cllect*. elleci* ol temperature and humidity. ofl'-gas*ing (related to storage!, exposure to const a nt. it w ould appear that three factors have the greatest mixtures, problems associated with applicable analytical effect <'n variability . These tactorsare the twoalready identi fied. temperature and pressure, and. less readily apparent, the velocity of the air external to the badges. methods, and adsorption ol the contaminant by the hadgi itself with subsequent leaching to the sensing surface. The possibility of adsorption by the badge body, thus giving i Ameiicar induvtna, A*soc>ai'On JOURNAL (A3) 8 V 3H 111062 higher results if the contaminant is subsequently released to concentrations. In this case the error in the instrument can the active medium, is of special concern in using passive be calculated or estimated. Charcoal tubes and critical ori dosimeters to measure very low ambient concentrations fices also have been used to measure "known" concentra such as might be found in air pollution studies. Such interest tions. If error in both the "known" concentration and the concern are evidenced by research on the subject being estimated concentration are considered, statistical tests used |sored bv the U S. Environmental Protection Agency to validate the experimental method become considerablv Vi "" Because of the lower concentrations involved with more complicated: hence, the error in measuring the "known" air pollution studies as opposed to work place env ironments. concentration is usually assumed to be small and unimpor- the EPA also is concerned with the background or post- tant.191 Methods described above fordeterminint the "know n" manufacture contamination levels associated with the sens concentration vary in their accuracy , a fact which should be ing medium. Initially, the focus concerns organics and acti- considered when evaluating validation data for any sam v ated charcoal. pling and analytical method. In summary, although numerous factors may affect the linn! calculation ol concentration, only face velocity and the determination ol the diflusion coefficient are unique sources ol error for passive collectors. Therefore, if face velocities are sufficient to prevent "starvation"(probahly greater than When one is validating a method in the laboratory, there are two main considerations: the variation of the samples or data points about their mean, and the deviation of the sam ple mean from the true mean or"know^"concentration. The 7.5 cm see) and if diffusion coefficients have been accurately first consideration often is called precision and is probably calculated or experimentally determined, passive dosimeters the most important and reliable measure as it does not should giv c results comparable to those obtained w ith tradi- depend on the error in determining the "known"conccntra- ional active sampling systems. tion. Precision is estimated by determining the coefficient ol variation (CV) or relative standard deviation of the data set statistical considerations as follows: In evaluatingany new monitoring method.extensive laboraory and field testing is necessary. Interpretation of the CV = -^-X 100 (7) . esults of these tests requires the application of appropriate statistical techniques. The use of statistical techniques which .ire meaningful and easily understood is important: conse where: s = Standard deviation of sample data set. and X = Mean of sample data set. quently. a discussion of the techniques used to evaluate ive dosimeters is appropriate. here are numerous statistical tests which can be applied oth field and laboratory validation data. The main diference between the two situations is the degree of certainty "if the "true" concentration of the monitored environment, in the field, the true value is usually an estimate based on the esults of a standard sampling and analy tical method. In the ahoratory. experimental "know n"concentrations areev olved and are then used for comparison with thc'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 "known" concentrations. These errors are often difficult to estimate. The "known"concentration is often calculated by weighing a syringe before and after an injection period (mass valance) or simply by injecting or allowing to diffuse a ncasured volume. It is assumed that the aliquot delivered vas v aporized or diffused into a test chamber of known size. 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 `known "concent i at ion. For example, an infra-red (1R)ana- y/cr or gas chromatograph may be used as a check on a ^inwn" concentration ^^Bn other instances an IR analyzer or a direct reading instrument may be the only method fordetermining"known" Where samples arc taken at several concentrations, it inecessary 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 are 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, are 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 are 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: b=x_XoX)oo Xn |8) w here; X = mean of sample data set. and Xo = "known" value at level tested. If more than one level is sampled, it is ncccxsary to determine the pooled bias of the data set.111' .01 Am Ind Hyg Assoc J (A3i AufuSI 19S. 3M 111063 The bins 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 indiv idual samples or the levels) are consistently negative or positive. If the bias is large and varies consis tent^ in one direction, the precision nevertheless may be quite small In this case a physical or chemical variable may be consistentlv affecting the method (a systematic as opposed to random error), causing the experimental values to con stant^ fall short or long of the "know^"concentration. This form of bias should be corrected. In addition to these statistical tests, others have been used to assess ihe validity of passive monitoring svsiems. Overall svstem accuracv'11' has been defined as (2 X CV) + absolute bias, expressed as a percent. Others'1'1 have used the percent age of the "known" concentration accounted for b\ the sample mean two standard deviations as well as the term systematic error"31*1 which is equivalent to overall system accuracv. Relative standard deviation has also been used, and is defined as the equivalent of CV.'1'1 Additionally, some authors report onlv 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 consistentlv use those determinations which give the most information in the simplest form. Certainly, bias and precision meet these criteria. Discussion ot one other point seems necessary. NIOSH1101 has proposed as a guideline for their own internal purposes that sampling and analytical methods meet a minimum requirement of 25 percent accuracv ; that is. the absolute total error of the method should be less than 25 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 critici7cd by some authors."6' it was adopted for NIOSH's own internal use and is not meant as public poliev. However. OSHA adopted the same criterion for the ben/cnc standard, w ithout a complete derivation or explanation. Consequently; this criterion has been criticized and alternatives have been proposed."" A second important point is that bias is also considered in the 25 percent criterion according to a somewhat complex statistical relationship,'10' but the overall sv stem 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 when 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 necessarv. If passive moni tor values, for example, arc plotted against charcoal tube American industnai H>$>ene Association JOURNAL fO 8 82 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 also have a value of one. If the individual values for the two devices 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 not subject to error. Of course, wc know and can calculate under laboratory conditions the error of active sampling svstems There are at least three reasons why this error is often overlooked. First, it is assumed that consideration oi the error in X would only cause small differences in regression analysis results. Second, in addition to laboratorv demon strated error, a range of errors introduced by varying env i 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 ma_v be as great or greater than that for Y. Finally, if the error 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.l,i0' Their gas detector for carbon monoxide involved an"easilv 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 ot semiquantitative device was certainly a forerunner o) those that are available today, though it was undoubtedlv aflectcd bv air velocity as a stagnant air laser was not emploved. An extension of Gordon and Lowe's concepts in the late I960*s provided the basis for Plantz et al. to develop a personal dosimeter for measuring hvdrazine. unsymmetrical dimethylhydra7ine and monomethvlhvdrazine.1'1' The reaction*of these compounds with a "colorimetric substance (bindone) produced a purple color, the intensity of which was dependent on both concentration and duration of expo sure. Color standards then were used to estimate the concen tration as a function of the time the badge was exposed to the contaminated air; consequently, the method was onl^ semiquantitative. In considering sources of error the authors noted that the purple color would also be produced bv all volatile bases that were tested, including ammonia, aliphatic amines, aniline and cigarette smoke. 3M 111064 609 Of interest in this review. however. arc quantitative devices based on the principle of either gas or sapor diffu sion or permeation through a stagnant air layer. The first such des ice to be reported in the literature was described by B^hnes and Gunnison in 19"73.<a21 Theirdev ice employed the ^^^ciple of gas diffusion to determine airborne concentra tions of sulfur dioxide and will receive further consideration subsequent Is To gain the best overv iew of the v a rious appli cations of these concepts, it is probably best to proceed by considering first the inorganic and then organic gases and v apors. inorganic gases and vapors ammonia In 1978. Ma/ur ct at. described the use of the Abcor G AS BADGE to sample employee exposure to ammonia (this device currently is not marketed).'*'*' The investigators replaced the charcoal pad nor malls found in the G AS BADGE with an acid impregnated absorption pad. Of three acids tested, phosphoric was most successful in pros iding the best approximation of theoretical concentrations. They deter mined. howevei. that volatile amines, specifically cyclohc.xy Iamine. could produce high readings, as high as 185 percent of the synthetic atmosphere. This led them to replace the glass fiber draft shield on the front of the GAS BADGE with a "charcoal impregnated glass fiber filter which had been pretreated with alcoholic KOH containing 0.1 percent surlactant " The charcoal served to adsorb amines as they dif fused into the dosimeter, while the KOH (aided by the wetting agent) eliminated irreversible ammonia adsorption the charcoal, which would have caused underestimation the ambient concentration. Additional laboratory exper iments demonstrated that storage time of up to 47 days, pi ior to analy sis. did not appear to adv ersely affect the results. More recently, DuPont has developed a commercially available system lor the measurement ol several airborne contaminants including ammonia. In 1981. Kring cl al. described Du Pont\ PRO-TE kT" sy stem for ammonia, nitro gen dioxide and sulfur dioxide sampling analy sis using a col orimetric' readout instrument.1*4 1 he ammonia badge relies on molecular diffusion of ammonia and subsequent chemical reaction w ith a solution of 0.7N boric acid a nd 0.03N sodium potassium tartarate (sit). After exposure, the reagent pack is removed from the badge holder and analysts is initiated by pre-smg reagent "blisters" w hich arc adjacent to the absorb ing volution This action causes the release of a modified Nes-ler's reagent and the subsequent development of a c red solution. For ammonia, ma ximum color intensity is dev doped at 425 nanometers. The absorbance of the sample is then compared against a standard curve based on Beer's l aw After determination of the precision of the analy tical method and verification of the linear range of the color chemistrv. laboratory testing was conduct 2 to establish the operational range as well precision and accuracy of the ov ei all meihod lsee Table I), The minumum and maximum xmns ol the sampling range were found to be 50 and 500 "pm-hours. respectively For an eight-hour time weighted average. t Vse values cortespond to oi.s-lourth and two and one-half times the current ACGl H Threshold limit Value of 25 parts per million.lA" In considering sources of error, environmental effects including temperature (10 to 40 C). relative humidity (10 to 80 percent). pressure(730 to 790 mm Hg). and face velocity (2.5 to 125 cm sec) were included. Ol 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 of 0.6 percent per degree centigrade was suggested. Also investigated was the storage stability of both unc.xposed and exposed badges. Results indicated that refrigerated sioiagc i' necessary to extend the shelf life of unc.xposed badges. Once the badge is exposed to ammonia and before the reagents arc mixed, the badges can be stored for one (room temperature) to three (refrigerated ) weeks without losing any absorbed contaminant Once the reagents ate mixed and color formation is started, the badge should be read w ithin 90 minutes. Additional testing results conducted by DuPont are shown in Table l.,Jt" carbon monoxide Shorand Anders, of the 3M Company, have described the 3M "direct-read diflusional monitor" for evaluation of exposures to carbon monoxide.'2 ' The principle involves the reaction of the carbon monoxide and an unreported reagent(s) to give a visible color change from pink to tan Theoreticallv. "if any pink color is observable at the end ol 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 for calculation ol the average concentration of carbon monoxide during the exposure period. The authors present summary results of laboratory evaluations using an infrared radiation dev ice to establish "known" concentrations (see Table I). chlorine Hardy et 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.'*'' 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 concent ration. 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 effect' of temperature, humidity. w ind velocity and concen tration are reported as presenting an error at the 95 percent confidence level, which is "less than 15 percent. 610 Arr Ina Hyz Assoc J (43* Au`l'" 3H 111065 Chemical Ammonia Nitrogen Dioxide Sulfur Dioxide Hydrogen Sulfide Mercury CO TABLE I Inorganic Gases and Vapors Laboratory Results Dosimeter' Bias'* Precisi n* Range" (ppm) Reference DP DP GB GB OP DP MDA GB DP DP 0.5 05 -3.2 -3.2 -0.9 -4 9 -1 -08 7.4 6.9 9.3 21 7 7.5 8.7 4.1 13.8 58 7.5 20-50 20-48 6-62 4-11 4-11 4-1 1 6-9 4.6-5 3 4-11 4-11 24 26 23 1 38 24 36 1 38 24 GB 15 3 3M 05 9 3M 17 2 3M 0.3 4 7 1 6-2 2 0.03-0 3mg/m' 0.05-0.2mg/m` 50-1830 1 32 33 27 Notes r. r. Hl E(i HI Hi K Kc. <; 'DP-DuPont Pro-Tek Colorimetric System Badges. 3M=3M Company Monitor. MDA=MDA Scientific. GB=Abcor GASBADGE "See text, equation (8) ' See text, equation (7) "Some values are rounded to nearest whole number ''Bias consistently negative ^Results derived from Table III of McCammon et al.,X!' "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 develop ment of the GASBADGE personal sampler.111 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 bv National Mine Safetv Company, and those for inorganic vapors are not currentlv marketed.) Applications involving inorganic gases relied on collective elements of an "appropriate substrate impregnated w ith 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 (R E A L. Inc.) w hich relies on the permeation of H2S through a dimethyl silicone membrane and subsequent reaction w ith a solution of 0.2N sodium hydroxide and EDTA.130' The colored product (methvlene 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. The authors note that a critical step in American Industrial Hygiene Association JOURNAL f4 J) 8 82 the development of such a device is the experimental deter mination of the permeation constant (see Equation 6). w hich involves 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 foran eight-hour exposure, with 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 times the current eight-hour TLV of 10 ppm.'251 Evaluations ol envi ronmental 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 days 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. Another approach forthe determination of gaseous hvdrogen sulfide has been reported by Gracdel and Franev.131' Their research involved using a semiquantitative method without a stagnant airlayerand reiving on the discoloration of lead-stabilized polyvinvl chloride (P\'C). The technique involves the diffusion of gas in a polvmcr and. at high HjS levels, the detection rather than the measurement of toxic levels of H2S. Screening applications for low level exposures also are discussed. 3H 111066 sit mercury In 1977. McCammon and Woodfin of NIOSH reported the result*, of a laboratory evaluation of 3M's mercury vapor monitor.<321 The monitor's operating principle ins olves molecula^^kffusion and deposition of mercury sapor on a gold -.u^BRte. The resulting ch. nge in electrical conductivity icros' the gold loil is related to the amount of mercury absorbed by the foil. Three other sampling methods, all of * hich ins olsed the actise mosement of air. also were investigated and include the LASL tandum sampling tube, the hopcalite tube, and the iodine impregnated charcoal tube. For the p.issise monitor, precision and accuracy, the effects of face selocity and temperature, and potential interferences sserc insestigated. Concentrations of mercury sapor in an exposure chamber sserc monitored ssith an ultrasiolet mer cury sapor meter, which in turn ssas calibrated by measure ments using the LASI. method. To determine precision of the monitors, I 2 dcs ices were exposed to a test atmosphere. Results from three measurements of the test atmosphere using the LASL method gase an "expected" concentration of 0.056 milligrams of mercury per cubic meter of air (mg m1). ssith a standard desiation (SD) of 0.002 mg m3 and a coefficient of variation (CV) of 0.037. Precision and bias calculated for the data gisen in Table III of McCammon ei a/.13' is summarized in Table I. A least squares regression analysis of ihe combined precision and accuracy results for the passive dosimeters versus the "known" concentrations gase a Y intercept of --0.004 mg m3 and a slope of 1.003. Tests for the effects of face velocities from 25 to 125 cm sec (50 to 250 Ipm) did not appear to have any adverse effect on p^^B'mancc. while variation of temperature experimentally cc^mrmcd its effect on both 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 inv olv ed 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 UV meter and the LASL 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 thanchlorme, also were confirmed. In lQ80. McCammon and his NIOSH and OSHA co workers conducted further tests of the four previously dcsc' bed mercury vapor sampling and analytical methods.'33' The design of this laboratory experiment involved intercomparison of four methods, and the findings suggested that the v ariability 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 passive dosimeter, exhibited cood precision ov er the concen tration range of 0 05 to 0.2 mg m3 as shown in Table 1. ^^fccently SKC. Inc., introduced a gas monitoring badge t^wduccd by G M D. I nc.) w hich uses the principle of molecula r d if! us i-in (suthout a stag nan! air layer) to collect mer cury vapor.'341 The sampling media is referred to as "Hydrar 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 material similar to `Hopcalite.' " Quantitative determination is made by chemical desorption of the mercury and analysis with atomic absorption. nitrogen dioxide In 1976. Palmes et al. reported the results of their evaluation of a personal sampler for nitrogen dioxide (NOa).135' This work was an extension of their earlier pioneering efforts in dev eloping a personal sampler, employing the principle of gas diffusion, for sulfur dioxide.'2*' In their design, the sam pling dev ice was a 1.3 cm (0.5 inches) acrylic tube. 7.1 cm (2.8 inches) long. At the "closed "end of the diffusion path (tube! were placed three stainless steel grids coated w ith triethanolaminc(TEA). TEA was selected because: I) it captures NCf efficiently. 2) it provides a stable sampling surface, and 3) it yields a chemical complex with NO.> that is very stable over time. Subsequent analysis yielded a colored complex whose absorption was measured at 540 nanometers. Results were then compared against a standard curve which obeyed Beers Law. The experimental evaluation of the NO; sampler involved chamber measurements compared with "known" values determined by the volume of NO* introduced to the chamber or the weight loss of NO2 from a permeation tube. Although neither individual nor summary results were pre sented. graphical comparison of the data indicated a clove agreement between the passive sampler results 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 NOa. 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 516 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 analysis. In the prev iously described studies with the GAS BADGE. Tompkinsand Goldsmith also monitored for nitrogen diox ide.'" Their summary results for 82 observations showed accuracies and precisions as summarized in Table I. Eightyfive percent of the observations were within 25 percent ot 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. /.<*.. concentration X time (see Table l).'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 includes a badge for nitrogen dioxide. Laboratory test results ot this dev ice arc show n in Table I.'3,1 3M 111067 Am Ind H>f Assoc J (A3) AufuSt 19S." sulfur dioxide As noted previously, pioneering work in 1973 on the design of a sampling device which relics solely on diffusion of gaseous contaminants through a stagnant air layer is attribJbted to Palmes and Gunnison.<xl> 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 conductrimetric 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 hygiene technology. The last of the three inorganic gases looked at by Tompkinsand Goldsmith in their studies of thcGASBADGE was sulfur dioxide.'11 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 dcsices using activated charcoal and then will turn to specific organics which rely on other collecting media. Chemical table ii Organic Gases and Vapors Laboratory Results Dosimeter* Bias" Preciionr Range1' (ppm) Reference Notes Carbon Tetrachloride Toluene Formaldehyde Beniene Ethylene Oxide Halothane Enflurane Acrylonitrile Hexane Vinyl Chloride Methyl Chloroform Tnchloro* ethyiene DPA DPA NMS DP DPB NMS NMS 3M 3M 3M NMS NMS R 3M DPA NMS 3M DPA NMS 0.4 0.3 -1.7 1.5 3.3 -4 1 1.8 -1.4 3 -2.8 0 03 -1.2 -0.2 -5.9 -106 2.4 -3.9 -6.9 -0.5 4.4 5.25 1.7 6.3 4.7 1.7 17 3.2 7.4 4.8 8.7 2 3.7 , 4.7 45 2 7.6 7.7 1.9 3-18 57-228 12-47 0.24.2 3-24 08-5.4 13-13 5 300 0.5-20 0.5-20 0.7-19 10-37 1.5-14 160-840 160-840 15-65 20-200 20-200 15*67 10 E 45 13 rj SS 46 13 FJ 1 E.G.J 53 1 44 J 44 J 39 13 FJ 2 HJ 48 1J 48 tlJ 12 48 IJ 48 E U 12 a3M = 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 BSee text, equation (8) , cSee text, equation (7) nSome values are rounded to nearest whole number ^Small sample sire Fltnowns were calculated using charcoal tubes with critical orifices. This could affect the bias measure `'Preliminary results MPermeation dosimeter 'Bias consistently negative JResults calculated from data provided in reference Amrncan industrial Hygiene Association JOURNAL (43) B '82 3M 111068 rivaled charcoal devices - of March. 1982. there were lour manufacturers of passive Mmeters which rel> on diffusion and subsequent adsorp>n on to activated charcoal: National Mine Service Com.nv^lASBADGE). 3M Company (Organic Vapor MoniD^^^Pont Companv (PRO-TEK.. G-AA and G-BR ga^rc Vapor Air Monitoring Badge), and the Mine Safety ."pliance Companv (Vaporgard Badge). In 1977. Tompkins and Goldsmith described the first mmercial passive dosimeter for monitoring organic pors.111 The GAS BA DGE relied on molecular diffusion of vapor into the badge and subsequent adsorption onto tivjted charcoal. The authors developed the theoretical nnciples olThe badge's operation, and discussed sensitiv ity temperature and pressure, face velocity effects, and sponse time. Preliminary results showing the badge's 'ponse to benzene, ethyl acetate, methyl ethyl ketone, and 1 yrene also were presented and were described as "very couraging" (see Table II). In ihe same sear. Silverstein reported results of laboratory .d tield testing of the G ASBADG E for acrylonitrile.1t!*' The suits ol the exposure of .17 badges to known concentra>ns m the laboratory are presented in Table II. The results dicate the acceptability of the GASBADGE for mcasureents of aery lonitrile over the range of 0.75 to 19 ppm. The He of exposure in the laboratory was not given, however, eld measurements did cover periods of up to seven hours, though temperature and relative humidity ranges were ported, data analysis to determine the effects of these inables was not presented Silverstein also looked at .^^tion efficiencies and determined that the best results J^Brcent) were obtained with four mL of two percent etone in carbon disulfide, I n 1978. Bamberger el a!, conducted a series of laboratory sts to evaluate the G ASBADG E Their approach mv olved e generation of known concentrations of solvents and ibsequent evaluation with charcoal tubes(active sampling) nd the passive dosimeter. To evaluate the applicability of ne dosimeter over a wide range ot compounds, the investimon included seven different organic compounds each .preventative of a different functional group Included in his study were: benzene (aromatic), n-butanol (alcohol), i-butyl acetate (ester), ixooctane (alkane), methyl chlororm (halogenated alkane), methyl isobutyl ketone(ketone), uj trichloroethylene (halogenated alkene). The diffusion 'etficient ( D) used was that supplied by the badge manufae.rer. except in the case ol isooctane which was reported as ng an unknown coefficient Computations involving iis >ompound relied on the coefficient for n-oetane. A v ariety of experiments was conducted toloo katawide range of questions. Their findings corroborated dosimeter conserns similar to those ofactivesystems using charcoal tubes, f g . minimum and maximum loadings are important, postimple contamination and loss can occur it the exposed bsorhent is not adequately sealed, percent recovery for tures is consistent with percent recoveries for single kounds. and differences in charcoal lots can give differYcsults Other tests confirmed the need for some air 4 movement across the badge lace and the lack ol elleet ol temperature changes over a small range I I I ' C). I he results ol the simultaneous sampling with 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 dcsoi ption elliciencies less than 100 percent can be accomplished lust us is dime for charcoal tube data In 1979, H irav a mu and I keda cv aluated t he up plica! 'on i ! the GASBADGE tor monitoring exposures to mixed sol vents.1 Their research involved dilteieni preparations ol activated carbon "felt" in place ol the supplied collection medium and exposure to mixtures ol n-he.xane. ethy I acetate and toluene. Summary (graphical) data indicated that the amounts of contaminant absorbed by the dosimeter were proportional to both the vapor concentrations and time ol exposure. Halliday and Anderson reported on the use ol the GASBADGE m monitoring tor halothane,' '1' Six observa tions indicated a range ol measurements Irom minus nine to plus ten percent ol the test atmospheres, fnlortunately. the authors did not report their procedure lor determining the concentration of halothane in the test atmospheres. In 1981. Evans and Horstman reported evaluations ot desorption efficiencies ot charcoal tubes and the Ci ASB A DC E for stv rene.1 For iiquid dosing they found the dosimeter to be similar to the tube, while tor vapor dosing the badge was superior. The authors suggested that the differences m results mav, have been related to the use ol coconut shell carbon in the tubes and petroleum derived carbon in the badsje. Thev did not explain why this difference would altect one method of dosing and not the other. In 1980. Anders and Mullins of the 3M Company pre sented results comparing the 7 M passive monitor with char coal tubes in sampling for mixtures of organic compounds 111 The laboratory tests included a binary mixture of toluene and methyl ethyl ketone; a tertiary mixture of benzene, toluene and xylene: and complex mixtures ol unleaded and leaded gasoline containing various alcohols. Although the investigators cited "excellent" precision and accuracy lor the dilfusional monitor, sample sizes were small, and the com plicated studv design and lack of raw data preclude the determination of precision and bias statistics. Mazur and his co-workers'1" conducted side-by-side laboratory and field tests with charcoal tubes and 3M orsianic vapor monitors to measure concentrations ol halo thane (2-bromo-2-chloro-l. 1.1-trifluoroethane) and enllurane (2-chloro-l. 1.2-tnfluoroethyI difluoromethyl ether) The results of the laboratory studies are presented m Table 11 and support the authors' conclusions that the dosimeters are a reliable method for the collection of enflurane and halothane. In 1980. L.autenberger er at. described DuPont's passive monitor for organic vapors.'11' 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 polymer. A dual sampling rate of approxi- Am Ind 4ssac J (A3) Aunuit 198- 3M 111069 mutely 50 or 100 ml mm i\ determined by the removal of one or hoih ol the dosimeter's protective covers. One aspeet ol their research inv olved experimental determination oft he diltiiMon eoellieient ol several ga'es and vapors. They reported that values calculated by I ugg'1' were within 10 percent of their experimental!} determined diffusion coellicient values. Preliminary experimental results were used to discuss lace velocity cllects. ranee and sensitiv itv. maximum and minimum sampling times, vapor retention, Morage Mahilnv. desorption efficiency. and overall badge efficiency. 1 he overall accuracy determinations were limited to four observations at each ol two concentrations ol carbon tetrachloride (see Fable II). However, the presentation of raw data, as well as an explanation of the statistical tests applied, is most usetul. I his same detail of information is also tound in DuPont's validation reports lor toluene and hcn/cnc (sec Table II). '' In the benzene report. DuPont also describes its PRO-TEK G-BB badge. This badge has a backup section ol charcoal, which serves the same purpose as the second section in a charcoal tube. /.t\. to aid m determining il the sampler has been overloaded. I he 3M Company also markets an Organic \ apoi Monitor with a backup section.'1'1 In studies ill the measurement of waste anesthetic gases with passive dosimeters. Jonas ei al. evaluated the CiASBADGE. 3M Organic Vapor Monitor and DuPont Pro-Tek in measuring enllurane. Bl l nfortunatcly. the badges were not identified in the presentation ol the results although interpretation of the reported sampler geometry would indi cate that A was the DuPont badge. BwastheJM badge, and C was the GASBADGE. The results of their laboratory studies indicated that badge 8 had the lowest coefficients of variation (CV was not calculated as described in this text) as compared to concentrations determined by infrared analyms Badge A had a low CV percent) at 5 ppm and a much higher \ alue l CV = 34 percent) at 20 ppm. The C badge had consistently high CV\ ranging from 23 to 30 percent. It should also be noted that the charcoal tube CV's ranged Irom I I to 27 percent, that desorption efficiencies for the badges ranged from 0.81 to 1.17. and that IR analyses of tank concentrations were constantly lower than expected. If badge B was the 3 M dev ice. the results of Jonas et al. support those reported by Ma/ur er a/.'141 Further testing of badges A and C seems necessary, however, to confirm their seemingly U'vv precisions. Ma/ur and his coworkers conducted additional tests comparing the 3M and DuPont badges against charcoal tubes 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 wereexposed tochamberconcentrations over the range of 160 to 840 ppm of methyl chloroform and from 20 to 200 ppm of trichloroethylene. Exposure times varied from two to six hours for methyl chloroform and I rom tour to six hours for trichloroethv lene. The laboratory work indicated that the percent recoveries of the various doses (concentration X time) were in good agreement except for one expo-ure of the 3M badge which involved a Five hour Jrv^r-cjrt `'dustrial Hygieri Association JOURNAL mi a. a? exposure al 700 ppm. The authors noted that this exposu ol 3500 ppm-hours exceeded the upper expo-ure limit pr vided by the manufacturer. The overall mean recovery valt for each type of sampler was used to correct all suhseque lield data. In addition to the recovery measurements, tl laboratory phase ol this study also involved determinant of storage stability. The authors lound no sigmlicant loss, of methyl chloroform ortrichloroethy lene from either bad; following storage of exposed badges for up to three week In 1978. West and Reis/ncr reported on the field tests t the MINI MONITOR'" (REAL. Inc.) permeation person, monitor for vinyl chloride.'"1 This monitor was a modi fit. version of one previously described by Nelms ft al."'" Th collecting medium was activated charcoal, but rather tha relying on molecular diffusion, the badge design involved polymeric membrane and the permeation of vinyl chloric through the membrane and adsorption onto the charcoa Initial laboratory calibration was used to determine th permeation constant ol the dev ice. I aboratory results ind cated good accuracies as summarized in Table II. During the same period that Tompkins and Goldsmith' were describing the GASBADGE. Bailey and Hollingdale Smith of Great Britain were presenting their ideas for . personal passive sampler for organic gases and vapors Their design involved the use of either one of two types e membrane and subsequent adsorption onto activated char coal. They found two membranes to be satisfactory, one o thin silicone rubber which acted as a permeation barrier, am the second a porous polypropylene film which allowed to molecular diffusion of the gas and vapor. They conducts laboratory tests using carbon tetrachloride, styrene an, dichlorodifluormethane. Their test results do mix some ter minology. e.g.. permeation rates for both the permeation device and the diffusional device, but did provide an earl' demonstration of the feasibility of such a dev ice for monitor ing certain organics. The device, the Porton Diltiisior Sampler, seems to see its greatest use in Great Britain. acrylonitrile One of the newest applications of passive dosimetry involvethe use of a porous polymer ( Porapak N) as the colleettnv surface with subsequent thermal desorption and gas chro matographic analysis. Benson and Boyce have described such a device and its utility in sampling for acrylonitrile Laboratory testing for acrylonitrile involved comparison o: the dosimeter values with concentrations measured on a gnchromatograph. Initial experimentation indicated that the dosimeter can be used for aery lonitnle concentrations in the range of 4 ppm. but at concentrations of 2 ppm a 40 percem error is reported. * aniline In addition to activated charcoal, another widely used adsorbent medium is silica gel. To study the utility ol th,material. Campbell and Konzen constructed passive dosirn eters from glass culture tubes (1.05 cm inside diameter) with 40 60 mesh silica gel as the collecting surface.Laboratory testing involved exposure of the dosimeter to aniline, with exposure concentrations determined by gas chromato graphic analysis of ethanol gas scrubbers. Three dillerent 3H 111070 sis size (length) dost meters were ev aluated. w ith ihe best results obtained with the intermediate length tube( L = 3.0cm: A L -- 0 3 cmi. The authors present raw data and clearly described their statistical techniques. oxide ^^nlins and Anders have recently described the 3M diffu se nai morn or tor samp!ing ethy lene oxide in air.'53' In this badge the collecting surface is described as a "chemically impregnated charcoal surface, (where) a reaction occurs producing a stable compound with a \apor pressure sub phosgene Matherne et al. have recently described the CMD. Inc "passivedosimeter"which providesa semiquantitativc mea surement of phosgene exposure.15,1 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 he logarithmically proportional to the phosgene dose overarangeof2tol00ppm-minutes. For qua nut a;, ve measurements the badges can be read colorimetricallv stantially lower than the parent compound." The authors present statistically summarized data describing the linearity and capacity of the monitor, the recovers of absorbed ethylene o\ide. environmental effects, sample stability, and the effects of potential interferences. Precision and bias are presented in Table II. other methods Hill and Fraser have described the use of commercial detec tor tubes modified to act as passive dosimeters.In then research, common length-of-stain detector tubes were modi fied by cutting off the conical end of the tube and remov mg some of the indicator column material. This leaves an oni ice formaldehyde with a cros'-secuonal area equal to that of the inside ot iru Rodriguez et al. have described another 3M diffusional tube and a path length determined by the distance from thi monitor for sampling formaldchvde.'54' In this diffusional end of the tube, to the beginning ot the indicator materia! monitor, the collecting surface is an "impregnated sorbent" One would expect, however, that as the sorbent nmtciial which can then be desorbed in suit with water and the becomes exposed, i.e.. the length of stain increases, the concentration of formaldehyde determined colorimetricallv. diffusion path length will also increase, thereby changing the Laboratory ev aluation first inv olv ed determination of recov sampling rate. Their evaluation of these devices involved ery coefficients, which at eight ppm-hours (19.5 micro- separate laboratory exposures to toluene, ethanol and i'0- grams) were found to be 1.00 0 04 over si\ tests. The next propanol. The results of their w ork, although presented onlv step involved determination of the dosimeter's "sampling in graphical summarv. demonstrate the potential lor the ti'C rate" ( DA l ) by exposing the dosimeters to "known" con of modified commercial detector tubes as passiv e dosimeter- centrations of formaldehyde as generated by a permeation tube The effect of relative humidity on the sampling rate was investigated, and evaluation of the data did not cate any statistically significant differences between the rates at 50 and 85 percent relative humidity The study protocol then inv olv cd simultaneous exposures of impingers (modified chromotropic acid method) and dosimeters The authors concluded that "the measured values by both methods lie within g: 25 percent of the expected response" and that "less variation is observed in the monitors than in the impingers." However, neither precision nor bias were reported. The authors also investigated effects of storage and determined that at elevated temperatures (38 C) losses up to II percent occurred after one week, however no signif icant loss was seen for samples stored at 23 C. The authors briefly discussed the potential for a negative interference from phenol and described the use of modified calibration curve' 'o address this prohlem. DuPont's PRO-TEK series of colorimetric Air Monitori-e Badges, includes a badge for formaldehyde. The collect.c.n principle involve' a chromotropic acid-sulfuric acid reaction. Laboratory ev aluation (42 samples/of the dev ice at seven exposure levels revealed results as shown in Table II l,v" Additional studies also were conducted on tempera ture and storage effects The raw data and statistical analy sis procedures are presented field validation Relatively few studies have been published in which passive dosimeters have been compared side by side with charcoal tubes or other conventional sampling methods under actual field conditions For inorganic compounds only two stud ies. involving nitrogen dioxide'59' and chlorine.' have been identified. For organic compounds, eight stud ies'3 91044 4"51 R"':' have inv olv ed field comparisons, with the number of compounds per study ranging from one to 22 In three of these studies, statistical analyses of data were no; presented and cannot be performed because of small sample size or insufficient presentation of data. Jones et al.<;>*' conducted a field evaluation for \CL 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 active sampling (pump i method gave a coefficient of variation (CV) of 8.7 percent while for passive tubes the CV was 5.8 percent. Regression ana! v sis (w here the active system was the X variable) of their data give's a correlation coefficient of 0.69. a slope of 0.59. and an intercept of 2.05 ppm fordata over the range of 3 7 to 5 5 ppm as sampled by the active method. This indicates that the dosimeter gave consistently higher readings which is K nese1 "5' has described a new passive dosimeter for formajdchvde which is a modified vetsion of the Palmes tube. ^Khc pi esent time experimental data concerning this dev ice IK not a ' ailable reflected in the means for the two methods: 4.51 ppm lot passive and 4.14 ppm lor active sampling. The authors did not report wind velocities, but low velocities, as would be expected with area samples, should have caused passive $16 Am Ind Hy( Assoc Jt4Ji Ajiu"' 3M 111071 values to be low as compared to acme values; this was not the ease. On the other hand, high face velocities could have led to the observed positive (passive versus active) bias. Hardy et al.'m reported the raw data results from a field evaluation of a permeation chlorine monitor (R EAL. Inc.). Thirteen comparisons were made in w hich the results from a battery 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 investigators performed a regression analysis using their permeation sample means for each comparison as the dependent variable. The results are quite good with a corre lation coefficient of 0 95. a regression slope of 0.85. and an intercept of 0.15 over a range of 0.0,' to l.l ppm as detected by the impinger. It should be noted that with five impinger samples ol less than 0.1 ppm. the corresponding permeation dev ices detected considerably higher concentrations (0.16 to 0.4 ppm). SiIverstcin1'11*' reported field results for aery lonitrile moni toring using 18 paired samples of GASBADGE passive monitors and active systems (charcoal tubes and pumps) over a range of 0.8 to 5.8 ppm as determined by the active method. The differences in results using the active system as a reference ranged from --0.7 to 1.5 ppm. 1 he difference in mea ns. 2,18 for the passiv c v ersus 2.73 for the active system, was 25 percent. Further data were not presented. West and Rets/net reported five sets of field results for viny I chloride sam pled w it h permeation dosimeters (REAL, Inc.) and charcoal tubes.'*' Further interpretation of their results is presented in Table III. In each case data for the active system are the X values Four 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 1.31). 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 3N1 Organic Vapor Monitors to complex mixtures of organic chemicals in tire manufacturing opera tions,"1' Generally the sampling period ranged from three to TABLE III Regression Analysis of Vinyl Chloride Field Data11' N Range (ppm) r Slope Y-Intercept 7 002-1 0 93 1 19 8 0.08-1 8 0 99 0 69 12 0 02-6 3 10 1.31 39 005-1.8 0.82 0.81 24 1 48 -16 7 0 96 1 08 0 03 0 05 0.01 0.11 0 43 Americar industrial Hygipn? Association JOURNAL (43) 8*82 five hours, and most observations consisted of one monito and the time weighted average concentration Irom twi sequentially exposed charcoal tubes Sixty-four of the set were personal samples, while the remaining 14 were are. samples. The samples were collected in two separate plant' (30 sample pairs in one plant and 48 in the other) Ot the 21 organics potentially available for analysis, 10 were detectec over a sufficiently w ide range of concentrations to allow to: appropriate statistical analysis by linear regression Tht. results are interesting in that in the first plant, 9 of the !( organics measured by the dosimeters showed higher vupor concentrations as compared to the charcoal tubes, while li the second plant only three substances had a regression slop, greater than one. The combined data for both plants did no indicate that the passive system was consistentlv hia-ec when compared to the active system. The authors did poin out that generally the Y-intercepis (Y = passive dosimetc data) were slightly negativ e. a finding w hich may indicates 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 char coal lube and passive monitor means at the 95 percent confidence level. The use of t-tests to analyse such data habeen questioned since the means of the two methods mav be very similar but the components of paired values can be considerably different.1191 This condition can only be rev eaIce through regression analyses. In 1980. Mazur el al.,AA reported limited field data lor halothane and enflurane measurements using both 5M Organic Vapor Monitors (OVM) and an active system (charcoal tubes and pumps). For halothane three paired samples were reported. The mean concentration for tin active system was 2.01 ppm while 1.9 ppm was reported Iothe OVM. a difference (relative to the active sy stem) of five percent. Only one data pair was reported for enflurane: 04u ppm for the OVM and 0.52 ppm for the active system Obviously, more data are needed to draw conclusionregarding a comparison of the two methods for these agents A second study by Ma?ur el al.tAS' reported field compar isons of passive dosimeters and active systems (pumps and charcoal tubes) in sampling for trichloroethylene (TCEland methylchloroform (MC). Both DuPont PRO-TEK and 5M Organic Vapor Monitors were used for the passive systems Personal samples included exposure of one each of all three monitors. Area sample results inv olved three av erage v alueone was the average of three charcoal tubes, and the other two, the average of two of each type of dosimeter For M C 11 personal and 7 area data points collected over time peri ods of 1 to 5 hours at 15 to 21 6C 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 C and 30 percent relative humidity were reported. 4 regression analysis in which the charcoal tubes were the independent variable was reported by the authors. I n each o; the following data sets the presented values involve TCE personal and stationary sampling followed by MC persona and stationary sampling. For the DuPont badge, regression 3H 111072 6; slopes of 1.0. 0 99. 0.99, and 0.98. and correlation coeffi cients of 0.98. 0 98.0.94, and 0.94 w ere obtained. For the 3M bodge, regression slopes of I OS. 1.06. 1.07. and 0.90, and correlation coefficients of 0.98. 0.98. 0.98. and 0.90 were de^rmined These values appear to be quite good: however, t^^pithors did not report if they tested the statistical signific^ffe of these values. They also did not report average of face velocities associated with stationary samples. Evans ei al.'6"' of Great Britain reported field validation data for the Port on diffusion dev ice w hilc measuring methvi ethyl ketone. In this case the conventional sampler was a pump and a cassette fitted with a charcoal cloth similar to that used in the Porton device. A regression analysis per formed with their data showed good correlation (0.9) and good slope (0.9); however, the intercept value (4.69) indi cated that, at low concentrations, the "home-made" dev ice gave lower values than those determined with the conven tional monitor Concentrations reported for the convenlional device ranged from I 1 to 189 ppm. Benson and Boyce1'111 field tested the Monsanto Poropnk s' device in Great Britain. Conv entional samplers consisted of pumps and Poropak N poly mer tubes. Sixty-five pairs of .amples were obtained, and the range of acrylonitrile meaured by the tubes was 0.13 to 21.65 ppm. Regression analyis of their data indicates only fair correlation (0.63). a low lope (0 46). and a negative intercept ( -- 2.06). These values tppear to result Irom the apparent inability of the passive ;ev ice to accurate!) detect concentrations less than 0.5 ppm. Mso. comparisons between values over the lower half of .oncentrations sampled showed considerable scatter. e final field study to be discussed suggests perhaps the serious discrepancies resulting from use of charcoal passive dosimeters.16,1 This studv was performed bv NIOSH versonnel in conjunction with industry-wide studies of the Irv -cleaning, screen printing, and boat manufacturing indusries. and also included one viscose rayon and one cellothane plant Carbon disulfide, pcrchloroethy lene. toluene. Ttcthylisobuty 1 ketone (MIBK). styrene, and acetone were ampled using the 3M OYM, the GASBADGE. and active ystems with charcoal tubes. The presentation of the study Jesign is not clear, but it appears that area samples involved all three devices while personal samples involved charcoal tubes and only one of either passive dev ice. In that this study nvolves six compounds in 64 plants, the volume of data is ,uite large. In addition to regression analysis, paired t-tests nd \\ ilcox signed rank tests were performed by the authors o determine equivalence of data sets. As noted earlier fn. u.-e of t-tests for determination of equivalence has Deer, questioned.'1*' Table 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- eyed 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 s sur\eyed with the OVM and GASBADGE, and one was 4keyed with the GASBADGE only. Foi the ranges of r Tirted in Table IV. the upper values arc quite acceptable, with the exception of carbon disulfide using the GAS BA DG E However, the correlation coefficient for carbon disulfide using the OVM was 0.95. The correlation data can be summed up as being extremely variable. Table |V also reveals that concentration had an effect on the correlation coefficient for three of the compounds, though this was true for both monitors only when measuring acetone concentra tions Regression slopes were as variable as the correlation coefficients. The authors tested the slopes to see if they were significantly different from 7ero, and for acetone and carbon disulfide a diflercnce could not be demonstrated for several of their data sots This indicated that there was no relation ship between the results obtained with the active system and those obtained with the passive dosimeter. For other com pounds. it w ould have been useful to test the difference ol the slope from one. which if not significantly different would indicate agreement of the two methods. In tests of equivalence of data sets, the authors noted that for all plant data combined, only toluene showed equality, and this for the charcoal tube-G ASBADGE (CT-GB) com parison. However, when results from individual plants are used, the comparison outcomes are quite variable. For perchloroethy lene. equality was reported for one of three CT-BG comparisons and for one of two CT-3M sets. For styrene, two of six CT-GB and no CT-3M comparisons showed equality For acetone, three of five CT-3M compari sons and one of six CT-GB data sets showed equality. In addition. GB-Ok M comparisons showed equality in 6 of I ' comparisons. It is obv ious that repeatability was not demon strated in this study. Whether the problem involves the dosimeters, investigative or laboratory techniques, and or env iron mental conditions cannot be determined. In t he only other field study of more than one plant. Hickey and Bishop'*'also 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 standard monitoring techniques. discussion Passive dosimetry (monitoring) is a rapidly dev eloping tech nology as witnessed by the proliferation of devices and applications since Palmes and Gunnison introduced their concepts just under ten years ago.1"'The latest entry into the Field comes from the MSA Company and involves an adap tation of their length-of-stain direct reading tubes for inor ganic gases162' w hich incorporates the application of molecu lar diffusion and a chemically 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 by ptacticing professionals, the development of a body of knowl edge demonstrating efficacy is necessary With env ironmental monitoring techniques, the determination of the elfieacy usually starts in the laboratory and culminates in the field In the case of passive monitors, a body of knowledge based on laboratory testing is rapidly being developed. Of the vari- Am Imi Hvf j/4Ji Aucust 19T 3M 111073 TABLE IV Major Results of a Field Study for Organic Vapors'*1' Concentration Substance Comparison Overall r Range of r Dependency Perchloroethylene Styrene Acetone Toluene MIBK CS CT-GB CT 3M CT-GB CT-3M CT-GB CT-3M CT-GB CT-3M CT-GB CT-3M CT-GB CT-3M 0 62 0 86 0 82 0 76 0 38 0 45 OBO 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 38 NA Yes Yes Yes Yes ables that have been studied, three appear to uniquely affect a diflusion monitors accuracy in measurinj: airborne concen trations of gases or \apors. The most important factor appears to he determination of the contaminants'diffusion coefficient (ot the sampling rate when the dosimeter's geometry is also considered), the wind \clocity at the dosimeter face, and the relative humidity of the sampled air. As discussed earliei, there are also a variety of potential sources of error, such as interfering contaminants, sorbent capacity and problems associated with anal) tical determina tions. which are common to both passive and active mea surement techniques. I aboratorv determination of sampling rates! DA Dfora speedic monitor and a specific contaminant are important and are being prov ided b> several dosimeter manufacturers lor an ever increasing number of compounds. Once an appropriate sampling rate has been determined, corrections lor field use. specifically for temperature variations, can be made The mam problem would inv olve situations where the env ironmental temperature lluctuated widely (more than 25 SC) and went unnoticed, a very unlikely condition. The research on effects ol lace velocities demonstrate that few problems should be encountered where dosimeters are worn bv workers as personal monitoring dev ices. T 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(at least what would normal!) be encounteied 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 iew 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 1 and II. where statistical analyses arc presented bv researchers, or where sufficient data are pre sented to allow the reader to determine bias and precision, the results are verv encouraging. Imlortunatcl) the presentation of experimental design, as well as sufficient data and or statistical analyses. are often lacking. This is true for some indiv idual researchers as well as for several manufacturers c the dev ices, especially those for inorganic compounds If or, recommendation regarding laboratory testing is made, would be that those researchers inv olv ed in the evaluation c passive dosimeters in the laboratory take the time to repor the conditions of their experiments, especially equipmer used and procedures for determining "know n" concentra lions, and as much detail about their results as possible. I summarized data arc presented, the author should preser, the known concentration at each level, where levels ar determined bv concentration and time, the number of obser vat ions made with passiv e dosimeters, and the average v alu and standard deviation of the results Statistical analvseagain at each level tested, should involve determination c the coefficient ol variation (precision) and the bias a described in equations (7) and (S). respectivelv. Once th evaluations are made at the various test levels, the determi nation of a pooled precision and bias is appropriate I: addition to these measurements, researchers may aN choose to present an overall system accuracy. 1 o develop . better understanding of appropriate statistical technique and their application to passive dosimetrv. a review o l.autenbcrger ei al. is recommended."1' For most active monitoring systems used in industria hygiene the random sampling error is usually associates. with the pump and is traditionally set at x 5 percent " lr many cases, especially lor the measurement of organu ' vapors, the analytical procedures and consequently thci associated errors are equivalent lor both passjse and activ-. systems. Nevertheless, both systems have random error consequently, one should not expect perfect agreement o the results of comparisons obtained under field test condi tions. Another factor complicating the evaluation ol ficlc results is the greatly increased possibility for the introduc tion of operator, or systematic, errors. Since active systemrequire mechanical pumps, the potential for operator erior would seem to be greater than for passive systems. Overall, it is apparent that existing field observationcomparing passive dosimeters with standard monitoring rftethods are highly varied. While some studies demonstrate good correlation and slope.'0**4"' others show only gone correlation.1' or are extremely varied lor both categories "" Collectively , these references neither support nor refute th-. use of passive dosimeters. Certainly environmental factor affect active systems as well as passive systems. In theory a case can be made that environmental factors (wind anc humidity ) affect passive systems to the greatest extent, w hilt temperature and pressure variations most greatly atks' active svstems. On the other hand one can also state that poor experimental quality control may affect such laetors acontamination. time measurement error, and analytics' error. Of course, chemical interterences may afteei both systems. As with laboratory experimentation, recommendation regarding the field testing of passive dosimeters involve u pica for better reporting ol both tield condition- and result' of analysis. First, for both personal and area monitoring, the estimation and or measurement of face velocity is impot- Ampncar indu^tual Asfutuwn JG'JRNAl (45 ? Z7 3M 111074 SI? tant, Of equal importance is the reporting of airborne con.aminams other than the one(s) of interest and en\ ironmena! variables including temperature, pressure, and relative hurmditv along with information as to their variation over .he period of observation. Again, if raw data cannot be tr^^ted. the reported results for each level tested (X value us^Brmined b_\ the standard method) should include the lumber of observations made with passive dosimeters, and heir associated mean and coefficient of variation. Statistical evaluations also should include a regression analysis of the data as outlined earlier. Undoubtedly. additional research is needed on the effect of not considering the error associated vith the supposedly, independent (X) variable. In summary, passive dosimeters show great promise as an mportant tool. The results presented in Tables I and II .ndicate that the precisions of the dosimeters are essentially equiv a lent to conv entional techniques and in mans cases the additional five percent error associated with mechanical umps makes passive dosimeter systems even more attracivc. This, coupled with their ease of use. lack of required ,ia into nance, acceptance by workers due to light weight, and mnecessary calibration make passive dosimeters extremely dvantageous. Certainly they will not replace conventional nethods. as these have their place, especially for area sam'ling. The continued and growing use of passiv e dosimeters, owever. should generate additional data documentingtheir eliability and eliminating doubts about their usefulness. cknowledgement he assistance of Dr. H. Kenneth Dillon. Head. Industrial I vxicnc Chemistry Section of Southern Research Institute. n^Bjcally review ing this paper is gratefully acknow ledged. eferences 1. Tompkins. F.C. and R.L. Goldsmith: A New Personal Dosimeter for Monitoring of Industrial Pollutants. Am. Ind Hyg Assoc J 38 371-377(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. Anal 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 42 104-111 (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 Persona! Moni tors. Contract Number 68-02-2686 i Hickey. J.L.S. and C.C. Bishop: Field Comparison of Char^^^oal Tubes and Passive Vapor Monitors with Mixed Organic ^wapors Am. Ind Hyg Assoc. J. 42 264-267(1981). 3 10. U S. Department of Health, Education, and Welfare: Doc umentation of NIOSH Validation Tests. NIOSH 77-185, Cincinnati (April. 1977). 11. Lautenberger. W.J.. E.V. Kring. J.A. Morello: 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. Pod lak and J.F. Mazur: A New Personal Sampler for Organic Vapors. Am Ind. Hyg Assoc. J. 39 701 -708 (1978) 13. National Mine Safety Company: GASBADGE Product Bulletin Chlorinated Solvents Performance Data. Oakdale. PA (1979) 14. National Mine Safety Company: GASBADGE Product Bulletin Aliphatic and Aromatic Performance Data. Oakdale. PA (1979) 15. Anonymous: Guide for Use of Terms in Reporting Data in Analytical Chemistry, Anal. Chem. 52.221 (1980). 16 Shotwell, H.P., J.C. Caporossi. R.W. McCollom and J.F. 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Moleculon Research Corp.: PROPLASTIC Chlorine Vapor Badge Information, Cambridge. MA. 30. Hardy, J.K., D.T. Strecker, C.P. Savariarand P.W. West: A Method for the Personal Monitoring of Hydrogen Sulfide Using Personal Sampling Am. Ind. Hyg Assoc. J. 42 283286 (1981), 31. Graedel. T.E. and J.P. Franey: Gaseous Hydrigen Sulfide Determination by Discoloration of Lead-Stabilized PVC. Am Ind Hyg. Assoc J 47:947-953 (1979). Am Ind Hyg Assoc J (43) August 1982 3M 111075 32 WcCammon, C S- and J.W. Woodfin: An Evaluation of Passive Monitor for Mercury Vapor Am. Ind. Hyg. Assoc. J. 38 378-386 11977) 33 McCammon. C.S..S.L Edwards. R.D. Hull. W J. Woodfin: A Comparison of Four Personal Sampling Methods for the Determination of Mercury Vapor Am. Ind. Hyg. Assoc. J. 41 528-531 (1980). 34 Cohen. H.J., R.K. Zahray. A.C- Misiaszekand H.J. Muranko: A New Passive Dosimeter for Mercury Presentation at American Industrial Hygiene Conference, Portland, OR (May 25 29 1981). 35 Palmes. E.D.. A.F. Gunnison, J. DiMattioand C.Tomczyk: Personal Sampler for Nitrogen Oioxide Am. Ind. Hyg. Assoc. J.37 570-577 (1976) 36 McMahon. R.. T. Klinger. B. Ferber and G. Schnakenberg: New Technology tor Persona/ Sampling of NO. and NO\ in the Workplace Preseniation at American Chemical Society Exposition Symposium, Las Vegas. NV(August 25-28.1980). 37 OuPont: PROTEK Colorimetric Air Monitoring Badge Sys tem Laboratory Validation Report, Nitrogen Dioxide Badge, TvpeC-30 El DuPont de Nemours and Company. Wilmington. DE (1981) 38 DuPont: PRO-TEK Colorimetric Air Monitoring Badge Sys tem Laboratory Validation Report, Sulfur Dioxide Badge, TypeC-20 El DuPont de Nemours and Company, Wilmington, 0E (1981). 39 Silverstein. L.G.: Validation of Abcor GASBADGE for Acrylo nitrile and Improved Desorption Efficiency. Am Ind. Hyg. Assoc J. 38 412-413 (1977) 40. Hirayama. T. and M. Ikeda: Applicability of Activated Car bon Felt to the Dosimetry of Solvent Vapor Mixture. Am Ind. Hvg Assoc J 40 1091-1095(1979) 41 Halliday. M.M. and J. Anderson: Determination of Halothane n Operating Theatre Air by Using a Passive Organic Vapor Dosimeter The Analyst 105 289-292 (1980). 42 Evans. P.R, and S.W. Horstman: Desorption Efficiency Determination Methods for Styrene Using Charcoal Tubes and Passive Monitors Am Ind Hyg. Assoc J. 42 471476 (1981) 43 Anders, L.W. and H.E. Mullins: Comparison of Diffusional Organic Vapor Monitors with Charcoal Tubes for Sampling Laboratory Challenges to Contaminant Mixtures Presenta tion at American Industrial Hygiene Conference. Portland. OR (May 25-29. 1981) 44 Mazur. J.F.. G E. Podolak. G G Esposito, D.S. Rinehart and R.E. Glenn: Evaluation of a Passive Dosimeter for Col lection of 2-8romo-2-Chloro-1.1,'I-Tnfluoroethane and 2Chloro-1,1.2-Trifluoroethvl Difluoromethyl Ether. Am. fnd. Hvg Assoc J 41 317-321 (1980) 45 DuPont: PRO-TEK Organic Vapor Air Monitoring Badges " Laboratory Validation Protocol lor Diffusion-Type Air Moni toring Badges with Solid Solvents. E.l. DuPont de Nemours and Company. Wilmington. DE (1981). 46 DuPont: Laboratory and Field Validation Report for PRO-TEK G-BB Diffusion-Type Badgesfor Monitoring Benzene Vapors. E I DuPont de Nemoursand Company. Wilmington. DE(1981). 47. 3M C mpany; 33520 Organic Vapor Monitor with Backu Section. St. Paul. MN 48. Mazur, J.F., D.S. Rinehart. G G. Esposito and G.E. Podolak Evaluation of Passive Dosimeters for Assessing Vapc Degreaser Emissions Am Ind. Hyg Assoc. J. 42 752 756(1981) 49. Nelms, L.H., K.D. Reiszner and P.W. West: Personal Vin> Chloride Monitoring Device with Permeation Technique fc Sampling Anal Chem 49 994-998(1977), 50. Bailey. A. and P.A. Hollingdale-Smith: A Personal Diffu sion Sampler for Evaluating Time Weighted Exposure tc Organic Gases and Vapors. Ann. Occup. Hyg 20 345 356(1977). 51. Benson, G.B. and G.E. Boyce: A Thermally-Desorbable Passive Dosimeter for Personal Monitoring of Acrylonitrile Ann. Occup Hyg 24 55-75(1981) 52. Campbell. J.E. and R.B. Konzen: The Development of Passive Dosimeter lor Aniline Vapors. Am. Ind. Hyg Assoc J 41 180-184(1980) 53. Mullins. H.E. and L.W. Anders: A New Innovative Diffu sionalMonitor for Sampling Ethylene Oxide in Air Presenta tion at American Industrial Hygiene Conference. Portland OR (May 25-29. 1981). 54. Rodriguez, S.T., P.B. Olson and V.R. Lund: Colorimetric Analysis of Formaldehyde Collected on a Diffusional Moni tor. Presentation at American Industrial Hygiene Coher ence. Portland, OR (May 25-29. 1981). 55. DuPont: PRO-TEK Colorimetric Air Monitoring Badge Sys tem Laboratory Validation Report. Formaldehyde Badge. Ser ies II, Type C-60. E I. DuPont de Nemours and Company Wilmington. DE (1981). 56. Kriesel, R.S.: Formaldehyde Vapor Detection -- New Sam pling Technology. Presentation at American Industrial Hygiene Conference. Portland, Or (May 25-29. 1981), 57. Matherne. R.N., P.L. Lubsand E.J. Kerfoot: The Develop ment of a Passive Dosimeter for Immediate Assessment of Phosgene Exposures. Am Ind. Hyg. Assoc. J. 42 681684(1981). 58. Hill. R.H. and D.A. Fraser: Passive Dosimetry Using Detec tor Tubes. Am. Ind. Hyg. Assoc. J. 41:721 -729 (1980). 59. Jones, W., E.D. Palmas, C.Tomczykand M. Mitts n: Field Comparison of Two Methods for Determination of NO. Con centrations in Air. Am. Ind. Hyg. Assoc. J. 40 437438(1979). 60. Evans, M.. M. Molyneux, T. Sharp. A. Bailey and P. Hollingdale-Smith: The Practical Application of the Portor Diffusion Sampler for the Measurement of Time Weighted Average Exposure to Volatile Organic Substances in Air ' Ann. Occup. Hyg. 20.357-363 (1977). 61. Zaebst, D.O., M.F. Boenigerand J.R. Burg: Field Compari 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: Colori metric Personal Dosimeters for Some Inorganic Contami nants. Mine Safety Appliances Co . Pittsburgh, PA. 29 December. 1981: Revised 8 February. 1982 Amencm industrial Hy(ifne Association JQuFNAl (*3! S V 3M 111076 62: